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  1. There's a lot of chatter about the use of dielectric grease. Permatex suggests that Dielectric Tune-Up Grease is a good barrier to oxidation at plugs, connectors and terminals. There are some online comments at forums that say not to place dielectric grease on connector pins. I've gone to the Permatex site, and the information is vague: "Protects electrical connections and wiring from salt, dirt and corrosion. Extends the life of bulb sockets. Prevents voltage leakage around any electrical connection. Also prevents spark plugs from fusing to boots. Required for modern high energy ignition systems." Another quote from the Permatex site: Directions for Connectors: 1. Make sure ignition system is off. 2. Clean surface with Permatex® Contact Cleaner. 3. Coat both parts of terminal contact with Dielectric Grease. 4. Reassemble, maintaining metal-to-metal contact. - See more at: http://www.permatex....h.mSLOFJcy.dpuf Also, here's the PDF product information download from Permatex: Permatex Dielectric Tune-Up Grease PDF.pdf 69.55KB 0 downloads In the PDF, Permatex cites uses for the Permatex Dielectric Tune-Up Grease: TYPICAL APPLICATIONS • Spark plug boots • Distributor cap nipples • Battery terminals • Ignition coil connectors • Headlamp connectors • Trailer electrical connectors The "metal-to-metal contact" reference may create suspicion for some about "Dielectric Tune-Up Grease". I've used this product for years around tune-up work without reservation. I searched around and found an engineer's assessment of dielectric grease that suggests Permatex Dielectric Tune-Up Grease should work well on a variety of pin connector materials without creating any kind of resistance or barrier to current flow. This commentary is worth reading: http://www.w8ji.com/...tive_grease.htm, the author seems well informed, experienced, and he uses a scientific approach. According to the engineer, metal-to-metal pin contact should result if pins are clean and not tarnished, with or without dielectric grease on the pins. It's realistic to presume that the degree of conductivity is governed by the tension of the pin and socket fit, not whether we use dielectric grease. Whether or not you use the dielectric grease, I would use a quality electrical contact cleaner to get rid of the oozing material at your PCM plug and terminals. Make sure you flush out all residue and allow complete evaporation to prevent dilution of remaining grease or any issues with spark arc hazards. I would at least place dielectric grease on connector lips to act as an effective moisture and oxidation barrier. Personally, I'm good with the use of dielectric grease, others can use their own judgment. For me, the engineer at the www.w8ji.com site confirms and clarifies its intended uses. Moses
  2. There are areas where you should not use dielectric grease, RTV sealant or anti-seize paste. One worth mentioning is certain oxygen sensors (O2 devices). Some O2 sensors draw ambient air where the wires enter the sensor housing. Sometimes There is a port like the vent opening shown in the illustration below. These O2 sensors depend on ambient air for a baseline voltage reading. Deviations from that point trigger the PCM/ECM/ECU to adjust or "trim" fuel mixtures. Be certain that you know where the O2 sensor's ambient air port or ambient air entry point is located. If at the connector, do not put dielectric grease, RTV sealant or anti-seize paste where it could block this air source. Know the type of O2 sensor used and how or where it draws ambient air. This generic O2 sensor image shows the vent to atmosphere. Air is sometimes sourced through a padding where the wires enter the top of the sensor. Do not plug this port or the area where the wires enter the top of the sensor: For more information on O2 sensors, Walker Products has a training guide on O2 sensors that is helpful. The guide explains the functions, troubleshooting and service needs of O2 sensors. Proper use of anti-seize on threads of new sensors is illustrated: https://www.walkerproducts.com/wp-content/uploads/2020/06/Oxygen-Sensor-O2-Training-Guide.pdf Moses
  3. Many Jeep owners need how-to information on checking valve clearances and adjusting the hydraulic valve lifters on the inline 232, 258 and 4.0L six-cylinder engines and the 2.5L Jeep pushrod engine. Between the model years 1971 and 2006, Jeep used these AMC-design 232, 258 and 4.0L sixes and the 2.5L straight four-cylinder engine (1983.5-2002). The hydraulic lifter and valvetrain design has particular needs, especially the valve clearances. When these engines develop valvetrain noise, owners often think a valve adjustment will cure the problem. In each of these AMC/Jeep engines, valve clearances are set during assembly of the engine, and adjustment is not necessary between engine rebuilds. If your engine has developed valvetrain noise, or if you are in the process of rebuilding the engine and need to know more about setting valve clearances, my HD video from 4WD Mechanix Video Network at Vimeo will assist. This video was originally a Q&A Vlog at the magazine, now available for a broader viewing audience through Vimeo. Moses
  4. Valvetrain noise and rocker arm interference after cylinder head work can be issues on the AMC design engines. Causes can include sluggish oil flow through the hydraulic lifters, the lifters bleeding down, or possibly excess valve/lifter clearance from valvetrain wear. At 200K miles, that's a very real possibility. Another possibility, since you're certain it's not a lower end bearing noise, is a carbon buildup knock (not likely with an MPI engine) or a piston-to-wall clearance issue. Piston skirt wear is likely, too. It works like this: Pistons naturally expand from heat. There is the normal piston-to-wall clearance to accommodate expansion when new. Over time, the cylinder bore wear creates cylinder "taper" toward the top of the cylinder. The piston skirts also wear. Over time, the cylinders and pistons wear. Cold, the engine was noisy, the pistons expanded, and for a while, anyway, the engine quieted down when warm. Now, the lifters are clacking, the cylinders are worn, the pistons have worn, and you get the sound effects! Another noise can be piston pin wear, which causes a double-knock rap...You would notice this clearly as a dominant sound when the engine is unloaded and you tip the throttle in and out. Use of an automotive stethoscope, a copper tube or a piece of PVC tubing can help isolate engine noise. Be aware that these noises will be transmitted widely and very exaggerated while using these sounding probes! At 200K miles, these engines have done a heroic job tugging a Jeep around. 2.5L models with 4.10:1 axle gears, which make the piston travel extreme over this many miles, wear an engine out sooner. An engine with this kind of mileage needs a suitable burial or rebuild it completely, restoring the short block and cylinder head to OEM specifications with pushrod lengths checked (changed if necessary) for proper valve clearance/lifter preload. Some want to swap an inline 4.0L six in place of the AMC 2.5L four, and that's not easy. I'd consider a smaller V-8 swap (GM LS 5.3L makes sense) as a practical alternative. The Jeep YJ and TJ Wrangler frames are, for unfathomable reasons, designed specifically for either an inline four or a six-cylinder inline engine. (You can see photos of the motor mounts I fabricated during a 4.0L swap into a 2.5L YJ Wrangler, and frankly, it would have been just as easy to install a hybrid V-8.) Granted, the 4.0L radiator, shroud and transmission locations were straightforward, although a four-cylinder YJ/TJ model uses an AX5 transmission, which would be replaced by a 4.0L's AX15 transmission. Aside from fabricating motor mounts, there would be wiring, cooling, exhaust, the AX15 transmission, 4.0L PCM setup and other changes. Moses
  5. Thanks for the detailed and quick reply Moses, very interesting tech. I think you're right it is probably multiple worn parts making clattering together. I am looking forward to tearing down this engine one day and seeing how it looks/checking the wear. This is Mike at MCE Fenders (MCE Mike on Facebook) and this is the lime green Jeep in our photos. (Also emerald green before it was painted) I've owned this Jeep since I was 16 in 2000. You are absolutely right, this is a testimonial for this engine. I am absolutely amazed at how problem free and durable this engine is. Since it doesn't have much power, and had larger than stock tires on it since ~60,000 miles, this engine spent a lot of time at full throttle and/or high RPM. It has had 31s and 4.10s for a few years, 33s and 4.10s for about 6 months, 33s and 4.88s for a few years, and has been on 35s with 4.88s since 2008. I could also go on about all the times it spent revving high in the snow, breathing dust in the Moab and PNW silt, and it has overheated a few times due to a water pump and electric fan issue. I always just kept the oil changed. I am probably not going to do an engine swap for a while - just not enough time right now and focusing on other Jeeps and the company, but am collecting ideas on what to do. I am definitely leaning towards a small V8. I don't want a huge powerhouse, I rather have reliability of the entire Jeep rather than a HP number on paper. So was thinking a Vortec 4.8 or possibly a 5.3. From the research I have done, the Magnum 5.2 and 5.9 are the "easiest" swaps for my TJ electrically, so those are also on the drawing board. One other idea is to try 505 Performance's new 2.5L stroker kit and head. (2.7 and 2.9 options) But I am still researching this. While the sound and power of a V8 is fun, keeping the light 4 banger but adding power might also be fun. In '08 I swapped the AX-5 for an NV3550 with junkyard parts, and bolted on a NV241-J to that. So I am thinking they will be fine with either option. The front axle is a high pinion 30 out of a Cherokee. This would probably be fine for the stroker 4 cyl. option, but probably need replacing for the V8. This Jeep doesn't have a rear axle at the moment, but it will probably get a D44 when I have time to get to this project. Too many options, haha! Mike
  6. The steering gear and linkage are vital safety concerns—yet the pitman arm on a 4WD Jeep or other light 4x4 truck can easily be installed incorrectly. With the popularity of oversized tires and suspension lift kits, many pitman arms get replaced long before there is a parts wear issue. A dropped pitman arm is often part of a suspension lift kit, and the pitman arm on a new or relatively new vehicle may get replaced with a dropped arm. Here are some procedures that I use when installing a pitman arm: 1) Never turn the arm against either of the steering gear's extreme left or right turn positions. Force against the gear in these positions can damage the steering gear internal parts—the gear is not intended to absorb this kind of force at either end of the worm or ball nut's travel. I like to keep the steering gear and pitman arm close to the center or straight-ahead steering position during pitman arm removal and installation. 2) When removing the pitman arm nut on a typical steering gear, there is a lot of force required. It is easier on parts to use an air impact gun and socket to remove the nut, as there is less tendency for the pitman to rotate...If you have the steering gear removed from the vehicle, consider holding the arm in a large bench vise (with the gear assembly free) while loosening or tightening the nut. 3) Once the nut is removed, use the correct pitman arm puller tool to prevent damage to the steering shaft and other parts. Make sure the tool fits properly between the backside of the arm and the neck of the steering gear housing, with enough clearance to prevent damaging the housing/casting! 4) There is considerable force with the pitman arm secured on tapered splines, so use extreme caution with the puller tool. Once the initial tension relieves, the arm will come off readily. 5) Clean up the sector shaft splines as needed. It is critical that the new pitman arm fits properly, an interference fit that demands clean mating surfaces. If installing a powder coated aftermarket pitman arm, I always use a suitable drill motor-powered wire brush to remove the powder coating from the tapered seat and splines of the new pitman arm. (I remove paint here, too.) Don't damage or dull the spline teeth in the process! Warning: If you mate a powder-coated part at the splines, you will get a false torque reading. There is a high likelihood that the pitman arm will loosen at the splines as steering force wears through the powder coating. If you have a powder-coated arm already installed, and if the arm has been in service, re-check the nut torque with the pitman arm in the straight ahead steering position. 6) Always use the required torque wrench and socket to bring the sector/pitman nut to proper torque. Again, make sure the arm is near the straight ahead steering position to prevent damaging the steering gear. The torque required is high, especially on a recirculating ball-and-nut power gear, much more than on a light-duty vintage Jeep cam-and-lever gear! Do not second-guess the torque setting. Use a factory or professional shop manual to determine the correct torque for the pitman/sector nut on your steering gear. 7) When reattaching steering tie-rods, make sure they are clean and free of debris. If the outer end of the new pitman arm has a tapered seat with powder coating or paint, I use a drill motor-powered wire brush to remove the powder coating and take the tapered seat to bare metal. 8) Attach a clean tie-rod ball stud to the pitman arm tapered seat, using the correct type nut (typically castellated or flanged self-locking) that comes with the tie-rod end. Flanged, self-locking nuts are often one-time use only. Consult the factory workshop manual for recommendations on replacing fasteners or use of thread locking liquid. Always use OEM grade hardware and fasteners. 9) Align steering joints, adjusting sleeves and tie-rod ends so that the ball studs are on center with the steering linkage aligned. Make sure none of the joints bind or run out of travel over the full range of steering turn positions and angles. Make sure that parts do not interfere with each other. 10) I always recheck the torque on the pitman and tie-rod fasteners after a short time in service. This is a safety precaution that may catch a part requiring a slight re-torque. Again, this is all about safety. Use of oversized tires places an even bigger load on these parts... Moses
  7. So I have a 96 Geo Tracker 5speed manual 4x4. I bought it from my uncle who said he had just bought a brand new clutch. However the vehicle when started will only shift into reverse. It won't shift into any other gear. If I start it with the gear in first the car doesn't lurch forward or seem to do anything abnormal, except once I shift to neutral I am unable to shift to any other gears except reverse again. When the vehicle is off I have no problem shifting to all gears. I don't have the slightest clue what to check. Any feedback could be very helpful.
  8. Many of us have workshop "habits" we've picked up that could be helpful to others. Sometimes its an easier way to perform mechanical repairs or a welding task, other times it has to do with space-saving techniques and approaches that give you more shop floor space. Is there a piece of equipment that has made a real difference and proven its worth? A way to keep the shop cooler or warmer that saves energy and cost? Safer ways to lift a vehicle and work beneath it? What saves time or makes a difference when you perform routine or specialized work? Let us know, everyone wants to improve shop efficiency! Your how-to insights would be helpful to others! Moses
  9. Good info, thanks. Here's an odd one I have been trying to figure out for years. I bought the Jeep at 57,000 miles ('97 TJ w/ a 2.5L), and now it has about 200,000. So I am assuming now it's worn out and am just going to swap it out. But, this is what it has done for years: First cold start of the day, it is quiet. After about 30 seconds or a minute of warming up, I can hear a valve clatter/tapping noise starting. It did this until the engine was up to temp, then would go away as long as the engine stayed running. If it sat for a while and cooled off, it would do it again until warmed up. This never impacted the engine's performance or drive ability, so I never really worried about it. But, in the last year of driving it, the noise would appear at about 30 seconds or 1 minute of run time, but would stay once the engine warmed up. It would be quieter once warm, but definitely audible. It almost sounds like a diesel. This Jeep has sat now for about a year and a half, but I am going to revive it this winter, as well as do another build on it. Also plan to swap the engine for something else, but will always be curious as to what was making this noise. When I have a chance, I am going to tear the engine down and see if that shows anything. It definitely doesn't sound like a rod knock, and is coming from the upper part of the engine. So I am assuming it is something in the valvetrain.
  10. Originally a Q&A Vlog question at the magazine, a Jeep owner has trouble with the gauges and engine tune on his early YJ Wrangler. I suggest several troubleshooting and diagnostics tools for checking circuits, grounds and voltage drops. The use of a volt-ohmmeter, lamp load test and other techniques apply. Wiring integrity and proper splices are also discussed: Trust you'll find this helpful... Moses
  11. My son has a 1994 Cherokee Country, 4.0 that starts fine and runs fine, but when you shut it off, it will not restart until it has cooled off. I replaced the ignition coil but the problem did not change. My son has purchased a crankshaft position sensor, but before we install it, I wanted some opinions from other XJ owners who may have experienced the same problem. Once we have installed the crankshaft position sensor, it cannot be returned if it doesn't fix the problem. I am not even sure that not starting when hot is a symptom of a bad crankshaft position sensor. Someone that my son knows suggested it. Any help or opinions would be greatly appreciated since we cannot really afford to just randomly replace parts in search of a fix. I have owned many Jeep Wranglers over the years, but never had a problem like this. Thanks.
  12. The magazine's YouTube Channel generates a lot of questions, and I encourage viewers to join us at these forums. A current exchange involved a viewer installing a 4.0L Jeep water pump and asking about how to seal the gasket and engine-to-block. This is worthwhile for our forum community, here is the discussion: Question from Ben D.: Did you use Gasgacinch between the water pump gasket and block? Looooong time ago I remember using RTV. Was it necessary? My reply: I like Gasgacinch on a cut paper gasket like the water pump. RTV can slough and find its way into the radiator tubes and clog. An even coating of Gasgacinch, on each side of the cut gasket, is wise. Gasgacinch resists coolant, gear lube, engine oil and other automotive fluids. It works well around higher temperature castings. Edelbrock private labels the product for its valve cover and intake manifold gaskets, each a higher heat area of the engine. (Gasgacinch is not for an exhaust manifold where I would use Permatex Ultra-Copper RTV or Permatex Copper Spray-a-Gasket Hi-Temp sealant.) Like many other professionals, I have used Gasgacinch in motorcycle engine work. My recent XR650R Honda project's rocker box to cylinder head seal is one example of a precisely machined, interference fit without a gasket, using only Gasgacinch for that fit. (There is no factory gasket here, just sealant.) This is a good discussion for the magazine's forums at: http://forums.4WDmechanix.com. Join us, Ben!...Moses I use Gasgacinch on transmission and transfer case cut gaskets, engine oil pan (cork, rubber or composition) gaskets, seal jackets and shells, bolt threads, and many other paper gasket and interference fit locations. It works well when coated evenly, and Gasgacinch has excellent tacking ability for holding an awkward cut paper or cork gasket in place during installation. The YouTube video series on the Jeep Cherokee 4.0L cooling system and water pump work is at: http://www.4wdmechanix.com/How-to-Jeep-4.0L-Water-Pump-and-Serpentine-Belt.html. Gasgacinch is a long time respected sealant and belt dressing, and yes, it can help preserve and quiet belts! Moses
  13. Good afternoon, I'm looking for information about all that we should know before servicing an axle. I'm not an experienced mechanic, so I like to investigate before mess it up. Which one will be the best fluid to fill up the differential? I've read about API GL-5 and 75W-90 specs for this. I've also read about a limited slip differentials and an additive to be required for that one. So, how can we identify the axle that we have, starting with this, I've read that the D35 has a plastic plug. But mine has a threaded one. What things can we look for, to identify the D35 and D30 axles? How can we identify or distinguish the limited slip one? Thanks in advance. Alberto.
  14. Moses, a friend of mine is having a hard time with his YJ when he tries to start the engine. He said that some times take more than 10 attempts cranking the engine but it wont run. When we had luck and get the engine running, it suddenly dies when driving, becoming a critical safety issue as it loses power steering and brake boost. A mechanic took the ignition components to a lab for testing, he said that everything is OK. (Coil, Distributor, Wires and Ignition module). Please share some of your wisdom that can help him to find where the problem is. Thanks in advance.
  15. Forum Member Alberto from Colombia did a rear axle lube change on his recently purchased 1989 Jeep Wrangler 4x4. He discovered that the Dana 35 rear axle differential case is missing the lock pin retainer for the pinions/spider gear shaft. This is a crucial safety issue and deserves its own topic. Here is a copy of my response to Alberto, we can discuss this further: "Alberto...The "missing" lock pin retainer on the pinions or "spider gears" shaft is very important, as this lock pin holds the pinions/spider gears shaft in place. Warning: If the pinions/spider gear shaft works its way out on a C-clip design axle, the axle shafts can slide inward, C-clips drop loose, and the axle shaft(s) can slide out the side of the vehicle. This results in severe damage or an accident due to loss of vehicle control. On both the C-clip and non-C-clip axles, if the pinions/spider gear shaft slides out, it can destroy parts or even cause axle parts to seize. The rear axle could lock up and cause a severe loss of vehicle control and an accident. According to the 1989 factory service manual (U.S. edition), your rear Dana 35 axle should not have a C-clip design axle. You should have press-on axle shaft bearings and bearing retainer plates at the outer tube ends of the axle housing. The retainers keep the bearings and axle shafts from sliding out of the axle housing, and the axle shafts with bearings are a snug fit into the axle tube ends. These "seal retainer" plates attach to the brake backing plate studs. Some differential carriers (typically those with C-clip axles) use a retainer bolt to hold the pinion shaft in place. These bolts are notorious for snapping during removal. This ends up a major problem, as the high tensile strength sheared bolt shank must be removed before the axle can be serviced. (I'll save this repair for when such a question comes up in the forums.) Most often, during axle shaft bearing or seal replacement service, the bolt snaps as you try to remove it. In your situation, if this is not a C-clip axle, you should have a pinion/spider gear shaft "lock pin" and not a lock bolt. You may be able to install a new pin with the differential still in the axle housing. Access may be an issue, but this part is very important. If you cannot install the lock pin retainer with the differential case and ring gear in position, you will need to remove both axle shafts and the differential case with the ring gear to access the lock pin hole. First see if you can access the retainer pin hole without removing the differential case. Here is the illustration of an "open" differential, not a limited slip. Zoom-in for details. (Your mouse scroll wheel may be necessary for this step.)...Note the role of the shaft lock pin, Mopar P/N S0455313. This may be a generic part number: 1989 Wrangler Rear Axle.bmp 7.52MB 1 downloads If you have Trac-Lok, that differential also uses a lock pin to hold the differential shaft in place. Here are the Mopar part numbers for the Trac-Lok differential spider gear (pinions) shaft lock pin: PIN, Retaining...83505019 (1987-89); 05252502 for 1990 You do need to take care of this lock pin issue right away, Alberto... Moses
  16. One of the best lessons learned from years of instructing and our forum discussions is the value of visual learning! Now, the innovative Vimeo On Demand streaming HD video program enables the streaming of 4WD Mechanix 'Tech and Travel' How-to Series HD videos covering a wide range of subjects. Under the 4x4 hood and chassis, on the motorcycle repair stand or from the work bench, I'll deliver step-by-step, close-up HD video details for shop technicians and serious DIY enthusiasts. As you would expect, the growing list of instructional videos will demonstrate best professional practices and proven procedures for each step in the process! 4WD Mechanix Magazine and 'Tech and Travel' Forums have become an online resource for reliable technical information, in depth 'how-to' coverage and off-road lifestyle content for Jeep®, 4x4 truck, SUV, OHV and dirt bike/powersports enthusiasts. Vimeo On Demand takes viewers to the next level with streaming HD video instructional step-by-step learning! By following the steps provided in each video, viewers can perform professional-level work, save considerable cost and gain valuable insights. Off-pavement, your 4x4 truck, Jeep® vehicle or dirt/dual-sport motorcycle must be reliable and safe. Performing your own work, the right way, can increase your self-reliance while enhancing your troubleshooting skills. Projects take time to complete. The Honda XR650R motorcycle upper engine rebuild project became the first Vimeo On Demand production. The work and filming experienced the customary parts delays, machine shop sublet time and unforeseen obstacles. For this reason, all rentals are for a generous 30-day period. This added value provides the time needed for viewers to perform quality work. The 4WD Mechanix 'Tech and Travel' HD Video Series at Vimeo On Demand brings select, highly detailed 'how-to' instructional videos and backcountry travel narratives to viewers. Streaming HD videos can provide close-up, professional insights and sharp HD 1080P detail—directly from your mobile device, laptop, PC or the latest big screen "Smart" television! Watch the growing playlist of available streaming HD videos at Vimeo On Demand! Moses
  17. Hi, all. I'm a new member from Bullhead City AZ. first post is with a problem that my 90 YJ base 2.5 is having. The engine seems to be running fine for anywhere from 5 to 15 minutes, then a very slight stumble (misfire) begins and within about three to five minutes it starts to act like it's starving for fuel and then dies. As soon as it dies, I can start it right back up (no delay) and it repeats the same thing over again. It seems to me if it was a plugged fuel filter or a loose connection, that it would not necessarily start right back up again. The thing that is weird is that there is NO delay when I start it up. It dies, then fires right back up and is fine for a few minutes. At first I thought maybe the vacuum air restrictor in the air box was closing down and starving it for air, thereby choking it out, but I'm not sure if that's it and when it starts to die I can't get out to the air box to open it up before it dies. It does not seem to do it if I just let it sit and idle in my garage. It only does it when I'm on the road. Any thoughts? ideas? Crank position sensor? TPS? Injector? vacuum leak that I am not hearing? Any Ideas on where to start looking would be welcome. Thank you. 2.5 TBI 4 cyl (110,000 miles) 5 SPD AX5 Trans NP231(?) Transfer case Craig Bullhead City AZ
  18. When you find that your engine repair includes cylinder honing, apply this process properly. The optimal honing finish will have the right cross-hatch pattern with correct angles. If you're unsure of the right "look" or angles, look closely at the photo below, the magazine's cylinder barrel after machine honing at L.A. Sleeve Company: Hand honing will involve the correct diameter stone hone or flex hone ("glaze buster"). Your cross-hatch pattern will depend upon the right pressure and speed of the hone as you run it up and down in the cylinder. At our tools forum, you will find my comments on the two most common cylinder hones and their applications. Once you choose the correct hone and decide what you want the cylinder wall to look like when finished, clean the cylinder carefully and take measurements. If you're honing in an automotive engine bay with the head off and the rods and pistons removed, make sure to protect the crankshaft journals from honing debris. This debris is abrasive and will instantly damage new rod and main bearings! Wrapping the journals with clean shop rags is one method of protecting the crankshaft. I like to use a suitable honing oil. Some will use an actual machine shop honing oil. I like "Lube Guard Assembly Lubricant" for its lubricating and cleaning ability. As you hone, the cylinder must slough off abrasive from its pores. There is both the cylinder material and the hone material to consider here, each highly abrasive! When honing, I like to use a rhythmic pattern up and down in the cylinder, moving the hone uniformly and with the same speed and force over the full cylinder. In the day, my mentors recommended moving the hone "in slowly, out quickly", and that pattern is good, too. If you're unfamiliar with the speed of a hone, try a one-second-down, one-second-up kind of count that's easy to follow. I use a 1/2-inch hand drill motor with cross handles if possible to maintain center while honing. Note: For some motorcycle barrels, it might be practical to use a drill press and suitable holding fixture for the barrel. Simulate the honing equipment found in an automotive machine shop. You have good speed (usually adjustable on most presses) and alignment control. Set speed to your needs. Use plenty of lubricant while honing this way! With a stone hone, you can adjust the stone pressure against the wall and also choose a suitable stone grit. If you have no idea what grit, there are usually manufacturers' recommendations for each stone set type. These are general recommendations and reflect speed and pressure as well. Cylinder wall material can vary widely. Iron is often alloyed with nickel or even chromium and moly like L.A. Sleeve Company's "Moly 2000" liners. If in doubt, use a moderate grit, it may take longer but will not chew up a cylinder wall and require re-boring. Warning: Both automotive and motorcycle engines that have Nikasil bore plating require special honing with a diamond hone. Do not attempt to hone this material with a conventional stone hone or glaze-buster silicone flex hone. Sublet honing to a shop with appropriate equipment. A good approach when determining a cross-hatch pattern is to match the original cross-hatch that is evident at the top of the bore above the taper. This ledge or "ridge" is not affected by the piston ring travel and therefore should show a pattern that the engine manufacturer (or a machine shop rebuilder) has used. Note: This works fine for most honing jobs, although there are some very exotic OEM hone patterns like the late '80s to 1990 4.2L inline six AMC/Jeep engines. Jeep had a problem with ring seating (likely due to consumers having no idea how to "break-in" an engine by that era). AMC went to a radical "swept" hone pattern: course, irregular and circular—not the conventional "X" look of typical power honing. The simplest ways to have a new hone job go sour would be failure to thoroughly clean the cylinder of debris after honing and failure to sufficiently break-in or "seat" the new rings. I tested many Jeep and other 4x4 trucks for OFF-ROAD Magazine in the '80s to mid-'90s (Argus Publishers days) and also tested vehicles on behalf of the Portland Oregonian newspaper in the early '90s. I recall several tests involving vehicles with very low miles on the clock that were using/burning oil. The cause was previous testers running these engines too hard without consideration for break-in. I never reported the oil consumption in these vehicle evaluations; this was driver error, not a manufacturing defect. In particular, I recall a 1989 Jeep YJ Wrangler with a 4.2L carbureted inline six that used a quart of oil every 50 miles and also a TBI Chevrolet Silverado V-8 pickup that used a quart of motor oil every 300 miles. Each of these engines had rings that had not seated. I was able to reduce the oil burning dramatically during my test intervals by simply treating these near-new vehicles with consideration and allowing the rings to seat properly. If given enough time, I'm certain the oil consumption could have been overcome. Some practical considerations include selecting piston rings designed for a reasonable break-in period. Unless building an all-out racing engine with forged pistons, I avoid "chrome" rings. Moly rings work very well and respond quickly to a properly finished cylinder wall. Make sure your cylinder(s) is spotlessly clean before applying either a light engine oil or Lube Guard to the cylinder walls for both piston and ring insertion and the initial engine startup. A new oil pump and pickup screen is always wise for automotive engines during a rebuild. You have the oil pan down anyway, replace the pump. For domestic engines, I've always run a Melling "High Volume" replacement pump and screen. Cheap insurance policy for a long engine life. Note: On motorcycle engines, at least measure the oil pump rotor and pump gears, check the housing for pitting and damage. Make sure parts are within specification from the manufacturer. Replace parts as needed. I'd like to follow up this article by creating an HD video how-to on cylinder honing. I'll look for an iron motorcycle cylinder or an engine block in need of honing. It would be productive to share the "art" of cylinder honing in video! Moses
  19. We all know the value of anti-freeze/coolant. Anti-freeze is essential for preventing casting cracks when you park the vehicle in freezing weather. By contrast, the coolant properties raise the boiling point of the solution, making our modern engines tolerate higher operating temperatures, which can provide more complete combustion of fuel and cleaner tailpipe emissions. Higher pressure radiator caps also help raise the boiling point. Every liquid cooled engine parked at below freezing temperatures requires anti-freeze. Specifications call for anti-freeze/coolant that is compatible with engine and cooling system metals. We follow these requirements to extend engine life and preserve the engine's castings, seals and gaskets, heater core and other vital cooling system components. In addition to the type of anti-freeze/coolant, there is the manufacturers' recommendation about the concentration or "specific gravity" of the anti-freeze mixture. For cooling in summer and reasonable anti-freeze protection in the winter, most manufacturers settle for the traditional minus-34 degrees F anti-freeze protection as a year-round mixture. A 50/50 mix of pure (straight) anti-freeze and distilled water will usually provide this degree of anti-freeze protection. (See the label on the container.) Some environments require even more antifreeze protection. However, most products limit the maximum anti-freeze protection to something like minus-60 degrees F or a maximum percentage like 70% antifreeze and 30% distilled water. A closed thermostat (new Cummins thermostat shown at left) and too much anti-freeze/coolant are a recipe for excessive pressure in the cooling system. The right amount of anti-freeze/coolant will raise the boiling point of the coolant. Too much anti-freeze/coolant can actually cause boil over and coolant loss, damage to the radiator or heater core, and a reduction in anti-freeze protection...You wouldn't want to overheat—or freeze and crack—this Cummins 5.9L inline six cylinder diesel's head or cylinder block by running either too little or too much anti-freeze/coolant! Warning: Do not attempt to increase the concentration of antifreeze for a temperature lower than advised on the label. Running a stronger concentration of anti-freeze than this will not provide better anti-freeze protection. In fact, with too much anti-freeze/coolant, the freezing protection decreases. Overly high concentrations or pure anti-freeze may lead to cracking a casting in freezing temperatures. As for boil over, the boiling point actually drops with too much anti-freeze concentration. The system may boil over—either during normal warm-up phase of the engine or at normal engine operating conditions! Anti-freeze is designed to mix with distilled water. If you run straight anti-freeze, there is a likelihood of high cooling system pressure during warm-up with the thermostat closed. The engine may also boil over within normal operating temperatures. In freezing weather, you can crack the block, a head or other castings by running either too much anti-freeze in solution or pure anti-freeze! Pure anti-freeze is not to be confused with "pre-mixed" anti-freeze coolant. "Pre-mix" is typically distilled water and anti-freeze mixed before packaging at a 50/50 ratio. This "pre-mixed" anti-freeze coolant is usually good for minus-34 degrees F protection in the winter and a boiling point of 260-plus degrees F in the summer—with the right pressure cap on the radiator or system. Boiling point increases with the use of a specific radiator cap pressure, usually 17 PSI or so for most modern engines. If the cap pressure is lower than the recommended OEM cap, the boiling point will drop accordingly. For this reason, it is important that your radiator cap is in top condition and holding proper pressure. Understand that a vintage vehicle with a much lower pressure radiator/cooling system cap will have a lower boiling point than 260 degrees F, even with 50/50 mix of anti-freeze/coolant. So, make sure your engine's cooling system is protected against both boil over and freezing. But don't use more anti-freeze than the mixture for the lowest recommended temperature protection on the anti-freeze/coolant container. (Typically, this mixture limit is indicated on the container's label.) Know whether the anti-freeze is pre-mix or pure anti-freeze. Make sure you allow the coolant to mix thoroughly before reading the protection level with an anti-freeze hydrometer or specific gravity tester. Too little anti-freeze/coolant is dangerous and leaves the engine unprotected against cold freezing. Too much anti-freeze/coolant can also lower protection against both overheating (boil over) and cold freezing. Anti-freeze requires the right amount of water to work properly. Read labels carefully. As a footnote, we're talking about the anti-freeze/coolant in the radiator and overflow tank. Always check the anti-freeze at the radiator after the engine has circulated coolant thoroughly, including through the heater core; to avoid severe skin and eye burns, remove the radiator cap only after the engine has cooled down completely! Loosen the cap slowly, stop at the first notch, and release all pressure before removing the cap. Prestone or equivalent tester like the one at left can be purchased for $5 or so at any auto supply. If you follow directions, this hydrometer can be accurate and a quick test for anti-freeze protection. At right is a Stant cooling system pressure tester for the radiator/cooling system and also for testing cap pressure. A Stant diagnostic tool kit like this has been in my tool set since 1981, and it still works great. The cooling system pressure tester has a variety of uses and is an excellent troubleshooting tool. Mix the anti-freeze solution in the overflow bottle to the same mixture you have in the radiator. After several complete heat-up and cool down cycles, the anti-freeze/coolant in the engine, radiator and overflow bottle should reach a uniform mixture. At that point, measure specific gravity with the anti-freeze hydrometer to get an accurate read on the protection level. Test the radiator cap's holding pressure with a pressure tester if available. If in doubt, install a new radiator cap. Periodically, test anti-freeze/coolant protection at both the radiator filler neck (engine completely cooled down first!) and at the overflow bottle. If the cooling system has been transferring coolant back and forth—cycling from cold to hot and back to cold over a long time—a quick hydrometer test at the overflow tank can be accurate. Moses
  20. With the growing interest in aftermarket radiators, performance and "aluminum" appear to be interchangeable terms. The Griffin radiator in our 1999 Jeep XJ Cherokee is just one example, there are many. Even OEMs have turned to aluminum when high performance efficiency is necessary. The 1999 Jeep XJ Cherokee with aftermarket performance radiator. Note the stiffer aluminum necks on these radiators. Gear type hose clamps work much better with these radiators. Aluminum radiators have aluminum necks. These necks can be stiffer and thicker walled than the traditional brass and copper radiator necks. While OEMs often use spring clamps (faster on the assembly line!) to secure hoses to the brass/copper radiator necks, this kind of sealing may not be suitable for these rigid aluminum necks! We discussed OE clamps during the Griffin aluminum radiator installation. In the time this vehicle has been in service, every OEM spring type clamp has been replaced with a high quality gear-type, adjustable hose clamp! Weeping and seepage occurred with the OEM spring clamps—especially with the range of temperatures experienced during the winter at our area...Overnight temps can drop to the 'teens or even lower, while a thermostat temp of 195-degree F occurs each time the engine warms up! At left is a quality worm gear hose clamp that works better with aluminum radiator necks...Middle is a custom T-bolt clamp that has a self-locking nut and can be readjusted as necessary. At right is the most primitive of OEM type clamps that do not work well over time. Tension of clamp at right is preset and often loosens with heat cycling over long periods of time or from recession into the aging hose. Always re-torque the worm gear clamp after heat cycling for a short time. You can also re-torque the clamp in the middle, a high performance Mishimoto stainless steel offering from Summit Racing. The more rigid aluminum radiator necks call for secure clamp loads. Tension constants are limited on spring type hose clamps. They can only hold to the preset tension at a given diameter. Making matters worse, heat cycling affects any metal, and this includes spring clamps. Spring clamps tend to tension less after higher mileage use. So, if you're switching to an aluminum radiator, or if your OE radiator or other hose necks are stiffer aluminum, consider using gear type or quality adjustable hose clamps. Make certain that you recheck the tension on these clamps after the hoses have heated and cooled for a number of cycles. Once these clamps are at the proper torque setting for a conformed hose, they will hold that setting for a very long time. Moses
  21. There's an epidemic problem with fuel these days, and many blame ethanol and winterized fuels as the culprit. Whether ethanol or MTBE is the issue, carburetor and EFI system clogging is rampant, especially in vehicles that set for long periods of time. This became clear when our XR350R Honda dirt motorcycle set for over a year with fuel in the carburetor bowls. This four-valve thumper uses two carburetors, and one has the idle circuit and a pilot jet. The engine ran flawless until parked, then would not idle after setting for a long time. Most of us are aware of this plague, especially owners of Jeep 4x4s, rock crawlers and OHVs that park for long periods. Essentially, gasoline and diesel fuel has a shelf life. These fuels break down over time. The result can be an inability to fire, severe engine ping and symptoms similar to extremely low octane performance. In the day, this would simply cause poor performance. A fresh tank of fuel would solve the problem. Remember that old barn find MB Jeep or Bultaco motorcycle that would not start? A fresh tank of fuel (pre-mix for the Bultaco, please), priming the carburetor, and the engine fired! Sure, the carburetor gaskets may have shrunk and they leak now, but we're running! Today's ethanol behaves like alcohol and bonds with any water in the fuel. This water, instead of laying low in the fuel tank, moves through the fuel supply system. Fuel filter materials, especially pleated paper, swell in the presence of water. This swelling serves as a safeguard to protect fuel injection and carburetor components: The filter clogs and stops fuel flow. Note: This can even happen from one bad tank of fuel (too much water content). We've all heard about or experienced the gas station that ran its storage tank to the bottom, where the water accumulates. The unlucky customers who pumped that gas wound up with clogged fuel filters. Back to the XR350R example, the stale pump gas in the fuel bowl and pilot jet caused such severe clogging of the jet that the jet could not be cleaned with carburetor cleaner! (Drilling a carburetor jet is a lost cause; the bit, even turned with finger tips, will scarf into the brass and increase the jet's bore size!) I replaced the jet with the proper size pilot and rebuilt both carburetors. The engine's dependability and performance immediately returned. So, if your 4x4, OHV, ATV or dirt motorcycle sets up for long periods, consider using a fuel stabilizer or other additives that will prevent fuel breakdown and damage from stagnant fuel. In the case of motorcycles and ATVs with petcocks, always turn off the fuel for both safety reasons and to stop flow to the carburetor. Drain the carburetor bowl(s) when your OHV or bike will set for long periods; most OHV carburetors have a simple drain plug on the bottom of the carburetor's float bowl. Don't overlook the "fuel station" on your toy hauler trailer, either! Use up that fuel or stabilize it. I keep stored fuel for no more than four or five months these days. If my 4-stroke motorcycle fuel can is setting that long with fuel, the fuel gets dumped into the street/trail driven XJ Cherokee and burned up. We do the same with the Ram/Cummins diesel and its 75-gallon auxiliary fuel tank. After 60-days without a lot of driving, I will run both tanks down completely, timing the refill for a period when fuel prices will not be devastating: This is a 110 gallon refill, and the 30-50 cents a gallon "futures-based" price hike can be costly. Does anyone have a gasoline or diesel fuel stabilizer that they find useful and effective? Please share... Moses
  22. I worked as a light- and medium-duty truck fleet mechanic in my early career. In this environment, vehicles must run well and safely. I performed any and all mechanical service work and preventive care on 22 vehicles and pieces of construction equipment. In the process, I found quick ways to "test" engines, chassis, brakes, steering, transmissions, clutches, axles and electrical systems. Some of those fundamental diagnostic skills serve me to this day. One area of testing was for internal engine wear, and at other forum topics, I discuss the use of compression, vacuum and leak down gauges. None of these tests, however, pinpoint wear on the engine's timing chain, sprockets or timing gear mechanism. The vacuum gauge comes closest, as it can show retarded valve timing or ignition retard effects, indicated by low vacuum at an idle with normal engine compression readings. Retarded valve timing indicates a worn timing chain, sprockets or timing gears. In the conventional ignition distributor (breaker point or HEI) era, there was a hint of timing chain wear when the ignition spark timing suddenly retarded (without a loose distributor housing). At one time, OEMs tried nylon coated camshaft sprocket teeth for quieter engine operation, and it was not unusual for the engine to suddenly show retarded spark timing with mysterious "white plastic" bits appearing in the engine's drain oil. Regardless of sprocket or gear design, I used my own quick test for engine timing chain wear without the need to remove the engine's timing cover. With a breaker point or breaker-less ignition distributor with a cap and rotor, the test is quick and straightforward: 1) Disable the ignition and starter, detach the battery negative cable if necessary...This timing chain or gear test will be easier if the spark plugs are removed, but this is not mandatory. 2) Rotate the crankshaft pulley in the direction of engine cranking, using a socket and ratchet wrench at the crankshaft bolt; make sure the ignition is disabled or battery negative cable disconnected. Bring the pulley to the TDC mark. 3) Remove the distributor cap. Note the position of the ignition rotor to the distributor housing. Mark the distributor housing edge with a crayon or marker if helpful. 4) Rotate the crankshaft in the direction opposite cranking, very slowly; you will be watching for the slightest movement of the distributor rotor. 5) As soon as the rotor budges, stop rotating the crankshaft. Note the number of degrees that the crankshaft has rotated. The distributor shaft and rotor will have rotated 1/2 that number of degrees, since this is a 4-stroke engine: There are 2 rotations of the crankshaft for each rotation of the camshaft. 6) This amount of movement should be slight for a timing chain or gears in good condition. Since the distributor shaft runs off the camshaft, this movement reflects the play at the timing chain or gear set. 7) Repeat this test if necessary, always bringing the crankshaft pulley slowly to the TDC mark in the cranking direction—without passing the mark. If you pass the pulley mark, rotate the crankshaft back 45-degrees or so and carefully bring it to the TDC mark again. This test indicates the play between the camshaft gear or sprocket and the crankshaft gear or sprocket. It works on most OHV engines and also L-head engines. From the earliest Willys engines with sprockets and a chain, through the gear set valve timing mechanisms, to the modern chain and sprocket sets, the principle remains the same. If you're trying to translate rotor movement to wear, my experience taught that approximately 5/8" of crankshaft pulley movement (8" or so pulley diameter), at the O.D. of the pulley, was considerable for OHV or L-head engines with a timing chain and sprockets. If the engine has timing gears, like the older Jeep L-head or F-head 134 four, movement should be less than this amount. You're talking about play between gear teeth. This is a rough test but useful when your ignition base timing has been retarding over time on a conventional distributor—and the distributor housing is not loose. On all engines, including modern EFI engines where the PCM/ECU controls spark timing, the distributor's rotor movement determines the amount of timing chain and sprocket or timing gear wear. The fleet engines I serviced and rebuilt at that time included Chevrolet, GMC, Dodge (slant six), Ford and I-H inline six-cylinder OHV types. These pushrod engines used either a timing chain with sprockets or timing gears, all with a breaker point ignition. Engines like the AMC/Jeep 232/258 and 4.0L are of similar design, beginning with breaker point, then electronic and finally PCM driven ignition systems. Moses
  23. This is one that should be common sense, but i have seen vehicles where the owners overlook this. Whenever you upgrade the alternator output to a vehicle, or change to higher amperage batteries, or even set up dual batteries, always watch where the wires are run very closely. When i wire everything up, i used heavy gauge wire, with insulated clamps to mount the wires to the inner fenders, away from anything that would cause an issue with it, and run the wires for the dual batteries through the firewall to the switch in a short piece of conduit bonded to the firewall. If you wire through a hole drilled in the firewall, with no additional insulation of any kind, the wire's insulation can rub through and cause it to catch the vehicle on fire. This can be easily prevented by using a readily available rubber grommet to insulate that one wire where it goes inside the cab. I have worked on many vehicles in the past where people don't pay attention to things that could cause an issue later on down the road. Safety should always be first and foremost in any vehicle repair or upgrade of any kind. On my 1994 Dakota, i have switched dual batteries, with the switch inside the cab, for ease of access, a higher output alternator, 1200 watt two channel amp, electric over hydraulic Meyers plow, 4 combination driving/fog lights on the front, hard wired 1800 watt power inverter in the cab, and all of the wires under the hood are run through PVC conduit that is attached to the truck with insulated hard rubber/metal clamps. The wiring in the cab is run through double layer flexible plastic, like the manufacturers use, that way i never have to worry about a fire, or a wire shorting out at the wrong time. I know running conduit isn't always practical in some vehicles, but even flexible tubing, and rubber grommets, are better than exposed wiring everywhere. And, no matter what you are wiring, from aftermarket lights, to stereo systems, to winches, plows, whatever it may be, zip ties are a very inexpensive and valuable addition to any toolbox.
  24. There are many diagnostic tools now available, mostly electronic, often in the form of leading edge apps and electronic diagnostic tools or simulations. While this is great for electronic fuel-and-spark system or overall powertrain diagnostics, there is one inexpensive and time honored spot check for the engine long block's* condition—the simple engine testing vacuum gauge. *Note: The long block is the engine block with all of the reciprocating parts plus the cylinder head installed. If the long block is in good operating condition with normal valve lift and valve timing, the rest of the engine's performance is about spark, fuel and exhaust tuning. Years ago, when I began working as a truck mechanic, the vacuum gauge was a standard tune-up item alongside a compression gauge. The vacuum test was considered quite useful for determining engine compression loss, vacuum leaks and loss, needed spark timing advance, the engine's condition under load, leaking valves and more! Hooking a vacuum gauge to your engine's intake manifold source (below the carburetor or EFI throttle body) can be very revealing. To begin, the vacuum should read steady. Depending upon the altitude at the shop, manifold vacuum should be in the 18-22 in/hg range at an engine idle under no engine load—with a stock or RV camshaft. If low, don't panic yet, the engine's spark timing may be retarded. Base spark timing has an overall effect on manifold vacuum, and advancing the timing will raise manifold vacuum. Of course, there's a limit to the amount, as the engine will begin to ping or detonate if spark timing is too far advanced for the fuel's octane rating. On modern EFI engines, timing is often fixed by the crankshaft position sensor (CPS) and the PCM/ECU/ECM software programming. The computer will instantaneously and continuously adjust spark timing. For tuning purposes, it's assumed that timing is adequately advanced unless the engine is in limp-home mode. Vacuum gauge troubleshooting and readings can include a wavering or fluctuating gauge needle. This is the sign of a valve that is not sealing or seating properly. If you see this on the gauge at an idle with the throttle closed and no load on the engine, suspect an unseated valve. Causes of an unseated valve(s) are burned valves, bad valve seats or valves adjusted too tightly. On an AMC/Jeep engine that has non-adjustable rocker arms, there are several causes for a fluttering vacuum gauge needle: pushrods too long, a surfaced block deck and/or cylinder head with the original pushrods, high valve stem heights, or a thin head gasket. Each can cause a valve(s) to remain open when they should be seated. Driven in this condition for any length of time will either burn a valve(s) or cause carbon buildup on the valve face and seat. Manifold vacuum is important enough to be part of the gauge cluster on race cars and other performance engine applications. The Auto Meter 2337 gauge (left) is dash mounted for continually monitoring a performance engine while operating the vehicle. At right is an inexpensive Equus 3620 Vacuum Gauge test kit. Maximum fuel efficiency depends upon the highest tolerable manifold vacuum—including spark timing advanced to just below the point of spark knock or detonation (ping)! Note the efficiency zones built into the readings for each of these gauges. Not a sophisticated tool but surely an important tool in your tuning equipment, the vacuum gauge says a lot about an engine's running compression and cylinder pressures. The gauge can help identify poor valve lift from worn camshaft lobes and lifters, unseated valves, low compression, retarded valve timing from a worn timing chain, retarded spark timing, vacuum leaks and losses, plus the overall engine condition and tune. Unlike both a compression gauge test and a cylinder leakdown test, the vacuum gauge is a real time, running engine test! EFI sensors that parallel a simple vacuum gauge test would be the MAP and idle air control signals. MAP factors for barometric pressure and altitude changes, important for onboard PCM/ECU/ECM tuning of an EFI fuel and spark management system. Moses
  25. I talk a lot about using a cylinder leakdown tester for pinpoint engine diagnosis. When you want to understand an engine's internal condition, the degree of wear or actual cylinder seal, this is the tool. You can narrow your findings to a bad intake or exhaust valve, worn piston rings, excess cylinder taper, a blown head gasket or an engine casting crack—even more findings if you're creative! For some, the cost of a leakdown tester is not justified. Maybe the tool will not be used beyond a one-time test of your vehicle's current engine. Maybe you're strapped for cash and simply cannot afford the least expensive tester. Regardless, I will share a very inexpensive alternative if you have access to an oxy-acetylene brazing torch, some air line fittings and an air compressor. The homemade tool consists of an old spark plug and an air hose fitting. Here are the steps: 1) Remove the ground strap from the spark plug end; grind away and wire brush any remaining, rough material. 2) Knock the insulator/electrode out of the plug, wearing eye protection—porcelain is like glass! 3) Use an air coupler fitting with male NPT threads that will roughly screw into the empty steel body of the old spark plug. 4) Carefully and thoroughly braze the fitting to the spark plug shell; make this a strong, air-tight seal. Remove any flux or rough surfaces to prevent blowing debris into the engine's cylinders. The homemade tool shown here is a special extension/adapter for leak testing at the hard-to-reach spark plug threads of the magazine's Honda XR350R, XR500R and other four-valve motorcycle engines. The principle is the same for making an inexpensive, homemade cylinder leak tester. The tool I'm describing works with your air compressor. Set the line pressure first to 60 PSI, which simulates low compression seal, then boost line pressure to 100-120 PSI. This higher PSI will create enough pressure to expand the piston rings and force the compression ring(s) outward against the cylinder wall. This is more like actual engine operation pressures. Here's how to do the check: 1) Before inserting the spark plug thread air adapter, disable the ignition system and remove the spark plugs for #1 cylinder and its opposite firing cylinder. 2) Make sure the #1 piston is at TDC on its firing stroke (verify with the distributor rotor position if necessary). Note that for #1 and its opposite firing cylinder, the crankshaft timing mark for TDC will enable quickly bringing the piston to top-dead-center for the test. 3) With the piston at TDC on its firing stroke, install the homemade spark plug thread adapter. Seat the plug adapter carefully. (Use the plug's original gasket to protect the head, especially if aluminum.) 4) Apply compressed air at the lower pressure first. You will follow up with the higher pressure. 5) Listen for leaks at the crankcase (oil filler cap removed); the tailpipe; and the engine's air intake. Caution: If you suspect a blown head gasket, remove the radiator cap before applying compressed air to cylinders! Otherwise, you can blow off a radiator hose or cause severe damage to the radiator at these test pressures...This also applies when testing with a ready-made cylinder leakdown tool. When through with #1 cylinder, you can rotate the crankshaft carefully (ignition disabled!), one rotation of the crank pulley. This will bring the cylinder opposite #1 to the TDC position for testing. The reason for using these two cylinders for a quick, general engine condition test is that each of these two cylinders can use the crankshaft pulley's TDC mark for locating exact TDC for that piston. Repeat the air pressure tests at the second cylinder. Finding the opposite cylinder to #1 is simple. Note the engine's spark firing order. On a Jeep inline six, this would be 1-5-3-6-2-4. The cylinder opposite #1 is #6, both pistons rise and set in sync. When #1 is at TDC, #6 is also at TDC, one is at its firing position, the other at the top of the exhaust stroke...For a popular GM or Chrysler V-8 with a firing order of 1-8-4-3-6-5-7-2, the two paired cylinders are #1 and #6. A Jeep four is 1-3-4-2. #1 and #4 pistons rise and set simultaneously. This follows suit for other engines, note your engine's firing order. This test is for rough results only, as you are not actually measuring the percentage of leak, rather you are trying to find a substantial leak. In cases where the rings are shot, a valve or valve seat has a burned notch on its edge, or a head gasket is severely blown between cylinders, or into the cooling port(s), this test can be a quick, accurate likeness to what you get from a leakdown test. The homemade tool can also be used as an air hold for changing valve springs with the engine's cylinder head in place. With the rocker arms loose and valves closed, regardless of piston position in the cylinder, you can keep the valves in position while you carefully remove the valve springs with an overhead spring compressor. Do not allow the valve to unseat, and keep air pressure applied. As a precaution, raise the piston to TDC for this procedure; that way, the valve cannot drop far into the cylinder. If you do any volume of engine work, an inexpensive cylinder leakdown tester like the OTC 5609 tool is cost effective. I just pulled up this "best buy" on line at $58 plus shipping: http://www.tooltopia.com/otc-tools-5609.aspx?utm_source=pricegrabber&utm_medium=cse&utm_term=OTC5609&utm_campaign=pricegrabber_r1 For that price, you may prefer buying the leakdown tool. A few engine tests, and you will more than pay for the tool in pinpoint diagnostic value. This is my Snap-On leakdown tester, which has paid for itself many, many times over since 1981. I have quickly diagnosed major engine problems and internal engine issues without engine or cylinder head removal. See my additional discussion about this tool in the engine diagnostics tool forum. Moses
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