Moses Ludel

A very neat, clean and pristine installation! Years ago, I had a 1955 Ford F100 pickup that was a testbed for engine and transmission swaps. I made mounts that fit to the factory engine and transmission mounting positions. This required virtually no modifications other than a few drilled holes. I eventually did restore that truck to a near stock condition. At the time, these now classic '53-'56 Ford F100 pickups were plentiful and popular for "hot rodding"—often brutishly modified. I can appreciate your concern for authenticity and option to restore your valued 1982 Toyota Hilux 4x4 to its original form. You have a classic truck. The early 4x4 Toyota compact pickups with a beam front axle featured the indestructible "300,000 Mile Club" 22R engine. I had three FJ40 Land Cruisers: 1971, 1976 and 1978. The latter two were extensively modified OFF-ROAD Magazine project vehicles, the '76 in the late eighties then the '78 in the mid-nineties. The '78 was a floor feature at the SEMA Show, Las Vegas...Toyota had it going on! Enjoy your truck. Moses

Nice install and welds. This kit does not "sandwich" the tubes with an upper and lower truss. The strength of these upper trusses and C-gussets is tremendous. They make up for the factory tube weaknesses. These beam axles often came to the dealership with excessive negative camber, likely from factory jig welding, the inherent welding (heat) risks or even from being tied down too tightly on a car transport. Off-road pounding on rocks with oversized tires will bend these axle tubes. Yours won't. Ever. Welded right, in "stitch" fashion with thorough cooldown before welding adjacent sections, the camber should be on specification despite the extensive heat exposure. Once together, a camber check will answer that question. Moses

53HiHood...I did some homework...The attached schematic is for your chassis wiring (Rubicon with factory lockers only) and helps explain the dash lamp system. It's complex. The dash lights are activated by the control module and interaction with the lockers. You may have cleared the issue with the front axle/locker wiring fix. You'll see the relationship in the wiring diagrams. If the problem returns, a sticky 4x4 mode switch is possible, though I would look for either debris in the transfer case or possible parts misalignment from wear. If you've heard unusual "noise" in the transfer case, drain the transfer case and sift through the lubricant for signs of chain or case (aluminum) wear. The mode switch could be malfunctioning intermittently. If the wiring and mode switch are accessible, jump or bypass the switch to complete the circuit and see if you get a distinct 4WD dash light with the key turned ON. If that doesn't do it, there are several other components involved with the dash light signals. Review this PDF of the wiring circuits for your 4WD (transfer case) and factory air locker indicator lights: TJ LJ Rubicon Transfer Case Switch.pdf Moses

Jeepdog...You photos are very helpful. Assuming that the MSD ignition is firing optimally, the plugs are showing every indication of a rich condition. The BBD without computer feedback could be jetted improperly (combined jets and metering rods) for a 258 cubic inch engine. Checking spark plugs for a rich mix requires testing the main jets on the carburetor's high speed circuit. You do this by running the engine at or near wide open throttle then quickly shutting the engine off. This can be done in a lower gear since the test is strictly rpm and throttle position related. Hold the throttle open steadily for a bit without over-revving the engine. Inspect the spark plugs under that condition. To eliminate confusion, the plugs should be relatively clean to start this test. The Carter BBD was popular on Mopar V8 engines. Considering the cubic inch displacement of these V8s, the carburetor jetting can vary widely. The base mounting pattern is the same as a 258 application. If there is a tag or stamping I.D. number on the carburetor, let's verify the original application. Otherwise, you'll need to disassemble the carburetor again and verify the jet sizes and metering rods. If jets are right, confirm that the carburetor is assembled correctly on the metering circuit. Note check ball(s) placement and make sure any check balls are in their correct locations. If this carburetor was rebuilt professionally or DIY, go over it carefully and verify all the linkage adjustments, including the choke pull-off. I have a lot of carburetor data if we can determine the BBD's original application. I snagged this schematic drawing (courtesy of Carbs Unlimited) of a typical Carter BBD carburetor without a feedback system. Note the check balls at positions #39 and #28 in this illustration. Check balls and their size are critical: Here is my rebuild of a factory Jeep 258 feedback carburetor. You can get instructions for your non-feedback carburetor from either a shop manual or a carburetor rebuild kit for your specific application carburetor: https://4wdmechanix.com/moses-ludels-4wd-mechanix-magazine-rebuilding-the-two-barrel-bbd-feedback-carburetor/ Your photos also reveal the way an inline six distributes fuel. This is a graphic example of the outer cylinders running leaner than the inner cylinders. Assuming that the compression is normal at all six cylinders, this lean/rich condition is typical of inline sixes with a center mounted carburetor and uneven length intake runners. Check the engine's compression just to be sure it's okay. Let's work through this... Moses

53HiHood...Glad the parts for the locker came through...What trusses and C-gussets did you use? Any pics of the trussed axle housing? We just discussed trussing at this JK Wrangler exchange: Moses

53HiHood...Congrats on the '06 Unlimited Rubicon LJ! Great wheelbase for directional stability. Lift kits help with the over-center clearance. You need wide wheels with negative offset to keep the center of gravity stable after lifting. The mode switch can be an issue...You can test that readily with a voltohmmeter and shifting through the transfer case modes. Internal transfer case issues can upset the mode switch, too. Check the fuse and electrical circuit first. The mode switch typically completes the ground, check the hot side for shorts. Let is know what you find... Moses

Jason1234...Let us know how this works out. Here if you have wiring questions...Happy New Year! Moses

goalie94...Ah, a Dana 30...Thought you had a Rubicon Edition with 44s. Is the Facebook Jeep a Rubicon? Or are you swapping a 30 front for another 30? (If so, your current axles are acceptable if you're on a tight budget or time constrained.) I do like the 4.56 ratios for stamina over 4.88s, and 35" tires are plenty unless you plan to drive rockpile trails like the Rubicon. If the net cost is only a couple hundred dollars, there's a strong argument for getting the trussed axles (if the trussing was done right and housings are straight after trussing) with 4.56 gears, the wheels, tires, axles, springs and shocks. Just be sure these pieces are as represented; diplomatically ask for pictures of the trusses to see the weld quality. The quality of the aftermarket gear set installations is always a crapshoot. Happy New Year! 2023 should be an exciting year for you and your growing family...Congrats! Moses

Excellent, predicted results, you should be very pleased with your work here. I am glad to know MOOG has this part and the part number. I had previously thought that SPC was the only source, and MOOG is a known OEM brand. (There must be a substantial market for ball-joint alignment corrections on these beam axles! Not surprising.) Thanks for furnishing the part number. Expand and see my comments below... This would pass for "stock" settings with camber being over-negative but not extreme. Thrust angle is good for an aftermarket suspension system. Rear camber is still puzzling, you should be able to live with it, though. If the steering gear is on high-center with the wheels pointed forward (straight ahead), these specs should be good geometry for handling, control and on-center driving. The natural return to center after corners will be good with either caster setting. Moses

Well, Mike, you'd be going full circle to the original plan, certainly an option. The 700R4 with the correct drop side 208 is a prospect. The 200R4 was common for Buick V6 models. You have the BOP bellhousing pattern, which means V8 engine parallels. There may be an early '80s Olds 307 or 350 V8 powered GM car that used the 700R4. (350 diesel cars would have the Olds BOP pattern, too, and they used the 700R4.) This could provide the front end of the transmission to mate with your V6. The output needs to be a 4WD application from a GM truck that used the 208. A hybrid transmission could be built with those pieces. GM upgrades make the late eighties (1988-up) units best. Build the transmission with those upgrades. 3.73s with 31" tires would be okay for a truck 4-speed box, especially for your planned usage. The compound low gear with your Dana/Spicer 20 transfer case would be a real asset and save clutch wear...Comes down to an automatic versus manual transmission. Have a safe and Happy New Year as you contemplate the Jeepster project for 2023! Moses

Mike M...Thought it was the SROD or RUG, not a bad approach, these were used with light-duty pickups and moderate horsepower in league with your 231 Buick engine. These transmissions have synchromesh on first through 4th/OD. No gain in the ratios, but you get overdrive. Have you considered a truck box like the SM420 or SM465 Muncie four-speed? The common version of the older SM420 transmission uses a non-synchromesh 7.05:1 compound low gear, and the SM465 has a 6.54:1 (non-synchromesh) compound low gear. Either ratio would offset the taller low-range gearing of the Dana/Spicer 20 transfer case (2.03:1) if you plan to crawl off-road. Many did this and ran taller axle ratios like 3.73s or 4.10s with 33" tires to compensate for no overdrive. (Your tires look close to that size.) 3.73s or 4.10s and no overdrive would be tolerable on the highway. What axle ratios does the Jeepster have? 3.73:1? As you recall, the SM420 and SM465 normally start out in synchromesh 2nd. To simplify, a Buick engine bolts to an SM420 or SM465 by using a stock Buick V6 passenger car three- or four-speed manual transmission bellhousing. The SM420 (used from 1947 to as late as 1967/early-1968 in GM light trucks) and the SM465 (1968-up) have the typical GM front bearing retainer index diameter. You could use either of these transmissions with a stock Buick V6 (passenger car) bellhousing and the correct crankshaft pilot bearing/bushing, clutch disc, cover, throwout bearing and release arm. You would need the transmission-to-transfer case adapter, which Advance Adapters can furnish. They have the correct bearing(s) and adapter ring as well. This approach has been a mainstay conversion for as long as Advance Adapters has been in business (1971). These rugged transmissions are now getting older, and a "good used" one would need new bearings and refreshing. The beefier and heavier duty SM465 was my choice for higher horsepower applications. I used one behind a 383 small-block Chevy stroker V8 in an FJ40 Land Cruiser magazine project vehicle...Either truck box would be overkill for the Buick 231 V6. Even the vintage SM420 is much stouter than an SROD, T14, T176, T150, NV3550, AX15 or any other Jeep light 4x4 transmission. The SM465 is much stouter than a T18/T19 truck box, more like an NP435. Wider YJ springs are a popular upgrade for CJs. The shackle reversal kit would need to be substantially built and well conceived. If not, the front driveline, axle caster angle and other factors will be off. The shackle position, shackle length and the spring arch must be correct to maintain proper axle/caster angle over the travel range and not force the front driveline through the transfer case. Moses

See comments on your note below, Mike, thanks for sharing. The Jeepster has tremendous potential—and you're finding it. Readers will be envious of the rust-free body. Wyoming and Nevada—high desert, semi-arid. The RTS sounds like the Ford F150 transmissions offered in the early '80s? Three speeds forward plus an overdrive 4th, right? The Ford units would be in the ballpark for a bellhousing pattern and such. Is that the transmission Herm works with now? Advance Adapters did a lot of work with the WC T5 when I was writing extensively for magazines in the eighties and nineties. They were direct distributors for the B-W WC T5 and did a lot of adaptations. Contact my friends there at 1-800-350-2223. Ask about the approaches you are considering. I like your rear fender roll work, a nice touch! One thing I would do with the chassis is a shackle reversal kit at the front springs. This would put your spring anchor ends to the front and the shackles at the rear of the leaf springs. This makes a dramatic improvement in handling and control. The stock front shackle setup (CJs and the Jeepster) has the frame pushing the springs and front axle forward from the rear (anchor) end of the springs. The shackle reversal kits (available for CJs, presumably for the Jeepster, try a bit of searching) are common for CJs and YJ Wranglers. For 1976-86 CJs, the shackle reversal is a must. The frame brackets for the front shackles are notorious for folding and breaking. Thanks much for the photos...Let us know where the transmission choice leads... Moses

goalie94...Really wise to not install the knurled joints in a housing C-end that had original (snug fitting) ball joints. Once removed, the knurled joints would create a loose fit for the next joints. The knurled joints are for slightly worn bores or to compensate for rusty material removed when an old ball-joint is frozen in place. Your alignment results were as I thought. The loose joint(s) with vehicle weight on them gave nearly the same readings as new ones. So, time for the 1.5-degree offset ball-joint. Great work, methodical and exacting. You'll have predictable results. Keep us posted...Happy New Year! Moses

Good to get your update, Mike M! I know how cold it is at your area—our neighbors just arrived home from the Casper Area. Winter. I like your equipment choices, lots of work done, on the home stretch now! Share more about the RTS transmission. I'm curious about this choice. Share photos when you have time. I'm sure the Members would enjoy seeing your work and how the Jeepster came together. The '84 CJ-7, if the front axle is not bent, should provide good pieces: a Dana 300 transfer case with helically cut gears, the front and rear axles (30 open knuckle with disc brakes front; AMC Model 20 rear, a very good axle once converted to one-piece rear axle shafts) and likely the venerable AMC 258 inline six. Lots of value for either keeping or trading. Have a wonderful New Year's Eve this weekend, stay warm and safe...2023 will be a good year! Best, Moses

Bob, I agree...Did you find the rarer 33T or a 33? The turbocharged version (33T) would have added benefits in torque and horsepower. It would also raise questions about the condition of the turbocharger that has "been setting for years". As shared in my first reply, I like your concept. There are now quite a few contemporary Cummins R2.8L four-cylinder "crate motor" turbodiesels in Scout and Scout II 4x4s, but the installed cost is high for the engine and laundry list of conversion components. The Nissan SD engine is proven, reliable and should fit the engine bay. The AMC 232 inline six was available in the Scout 800, which means more room for this diesel engine. The rugged A727 Torqueflite would work well but is limited to three speeds forward and a 1:1 direct drive (no overdrive). You have the converter housing pattern for using a Chrysler A518 4-speed overdrive (1991-93 4WD version) unit but would need to work out the kickdown linkage (which may be similar to the A727) and more importantly the transfer case to transmission mate-up. Your '66 OEM Spicer/Dana 20 transfer case will not bolt to the Ram A518 4WD output adapter. Transmission output spline count and transfer case input spline count also need to match. I'd like to see a couple of photos: 1) the A727 Torqueflite output adapter flange pattern and 2) your '66 transfer case front flange pattern. This should be the same, as Scout II kept the early Spicer Model 18/20 flange pattern through the 1980 models. However, confirm whether the output/input shaft spline counts are the same. The A727 is much easier to use if you don't need overdrive. If you use the Torqueflite, you need shift linkage and the kickdown cable plus the cable hook-up at the SD throttle. If the kickdown cable is available with the engine, that's a plus. If you don't have the Scout II shift linkage (floor console type), you can substitute a B&M or other aftermarket shifter. A new aftermarket shifter cable is available for the Scout II floor shifter. I would do a Saginaw integral power steering gear conversion on this chassis, especially with the weight of the diesel engine. (Does the SD engine come with a power steering pump and brackets?) Advance Adapters has Saginaw steering gear and linkage conversion/changeover kits, and here is another Scout resource (found online, I haven't met these folks) with another approach: https://dandcextreme.com/product/scout-80-800-power-steering-conversion-kit/. Most suggest avoiding the Scout II power gear due to its age and lack of availability. If a known Scout II "good used power gear" is available at the right price, that could be a starting point. Any gear that age would need refreshing/seals and likely some work, at least adjustments to factory specifications. Below are my general rebuild steps for a Saginaw 800-series gear. Here's the magazine search for additional Saginaw information: https://4wdmechanix.com/?s=Saginaw+steering. If you're on a budget with the power steering conversion, the Advance Adapters approach would adapt a common Saginaw 800 type gear shown in the video. Any steering gear conversion will involve installing frame mounting plates, either your welding task or sublet to a reliable shop. You need a pitman arm and steering linkage that work safely with your steering gear and the knuckle arms. Linkage must clear the frame and work safely and smoothly...Give Advance Adapters a call at 1-800-350-2223 for tech details. Will you be running the original closed-knuckle front axle and drum brakes? Or are you upgrading to Scout II Dana 44 front and rear axles with disc front/drum rear brakes? This is a popular approach for an upgrade: https://ihscout.com/product/disc-brake-front-dana-44-axles-matched-pair-scout-ii-terra-traveler/. Moses

No problem, Jason...Does the manufacturer's website have a downloadable (PDF) instruction sheet? (Some sites do.) If so, provide a link or the PDF. We'll see what the instructions say. Since the gauges are electric and not a pressure line oil gauge, the oil gauge should have a sender that either threads into an engine galley port or fits a "T" from the existing oil sender. The voltmeter should not present a problem, it simply needs a voltage signal, which can be from an existing terminal stud source (no wire splicing). Is the gauge set specifically for your Toyota application or "universal"? Either way, we'll figure this out. Moses

Hi, Jason...If you can share the instructions/wiring diagram that comes with the gauges, we can explore how to tap into your classic 4x4 without damaging its wiring. Upload the diagram (a photo, PDF or whatever works) to this topic. If there's an instruction sheet online at the manufacturer's site, please share. I can download a PDF and look it over. That will be our starting point. I understand your reluctance to damage or devalue any of the truck's systems...I do have early Toyota 4x4 Pickup shop manuals and may have a wiring schematic. Moses

Renix Numbers...See the information (photos) below. I included the bulkhead and ECU connections...Note that the bulkhead connector has numbers across the top and letters down the left side (instrument panel side view). The ECU connector is simply numbered. I have included the 1987-90 FSM XJ Cherokee wiring color codes for these as well. I included photos and also PDFs that you can zoom into for details. (Click on the photos to enlarge. You can zoom out on the PDFs for a full view, then zoom into the image.)...I captioned each photo to clarify its origin and angle: I have the 1984-86 factory shop manual (AMC/Jeep FSM number M.R. 244 for 1084-86) but not the electrical volume if available separately (common)...Above, the shop manual shows the ECM pinout for the 1986 XJ Cherokee 2.5L TBI model. (The color codes and wiring diagrams would be in a separate book.) I took this a step further and copied out of the 1989 FSM Electrical book and share those images below...If you have cranking with a no start, below is the 1986 FSM flow chart for a "No Start" with the engine able to crank over: Above is the 1986 manual M.R. 244 flow chart for a weak spark or no spark condition when cranking. If 1987-90 is the same color coded wiring, the images below will help. They are from the 1989 FSM for the XJ Cherokee and cover the ECU connector, wiring color codes/gauge and the bulkhead pinouts. Wire color coding is included for each pin on the ECU and the bulkhead connector: This is the 1989 bulkhead connector (the instrument panel side view), presumably the same for 1987-90 XJ and highly likely the same for your 1986 XJ, which looks similar...Confirm color coding. 1987-90 FSM bulkhead pinout and wire codes (likely the same for 1986, confirm color coding). Note the numbers across top and letters down the left side. Be aware that this is the instrument panel side when confirming pinouts. 1987-90 FSM pinout for the ECU 35-pin connector with all color codes for the wires and their pinout numbers. Looks similar to 1986 35-pin connector. Confirm wiring color codes and the approximate wire gauge. I am adding PDFs of each photo below. You may find the PDFs handy. You can zoom out and into the images for details: 2.5L Jeep 1986 TBI Cherokee ECU Connector Pinning.pdf 2.5L Jeep 1986 TBI Cherokee Crank With No Start Flow Chart.pdf 2.5L Jeep 1987-90 TBI Cherokee Bulkhead and ECU Connector Pinning (1).pdf 2.5L Jeep 1987-90 TBI Cherokee Bulkhead and ECU Connector Pinning (2).pdf 2.5L Jeep 1987-90 TBI Cherokee Bulkhead and ECU Connector Pinning (3).pdf Let us know whether the 1986 and 1989 (presumably 1987-90) XJ Cherokee wire color coding matches. The ECU connectors (35-pin) and bulkhead connectors look similar, and this should work out. Please confirm... Moses

goalie94...See below, I think you're on it...

goalie94...Great pictures and questions...See my reply below...

goalie94...See my reply below...

Hi, SomeBuckaroo! Let's walk through your reply...

Goalie94...Yes, you're really close...I would do the one ball-joint approach and bring that side to 4.1 degrees positive (1.5 degree correction for caster only). The camber is not a significant issue, as you suggest. Yes, I would rotate the tires regularly to be sure. (I've seen 0.75 degree of camber on new Jeep beam front axles. Either this is factory "normal" but out of specification range or from being tied down too tightly on a transport.) As this is negative camber, be certain the knuckle ball-joints and front unit hub bearings are okay and not worn enough to allow hub flange tilt. The rear axle is interesting. Negative camber. Not a dramatic amount but suggestive of a heavy load on the rear? Is this an OEM 44 rear axle? Axle bearings okay, no radial play at the shaft ends? Is your JK an Unlimited? Extra weight like armor/bumper, etc.? If you do the one ball-joint, you'll have a livable arrangement as long as there are no signs of physical stress or questionable damage to the axle housings. Moses

SomeBuckaroo...I am listening with great interest. You have taken a thorough and thoughtful approach to this project! To begin, my specifications for valve spring tensions came straight out of the 1998 Mopar™ Jeep® Wrangler Service Manual. I'll share here before replying to your comments and observations below. I use red highlighting to make it easier to follow our exchange: This set of specs is also found in the XJ Cherokee manual for 1998. Unless there is an FSM discrepancy worth noting, either these specs or yours should work as long as they allow for full valve spring compression without spring bind. Let's go through your experience and the legacy of this project. The end game is to see if the trouble symptoms can be eliminated:

Julio...Were you able to identify the thread size of the pressure test port plug? Take the plug and your pressure gauge to a NAPA store with a good assortment of fittings. You should be able to put together the needed fittings. If you are successful, please let us know the thread size and type of threads at the port (female) end. Chrysler offered a TBI "Diagnostic Connector" for testing the TBI fuel pressure. This connector (shown below) uses a Schrader valve and common EFI Schrader valve connection fitting. (EFI fuel rail pressure testing kits usually attach to a Schrader test valve at the fuel rail. For those on a budget, Harbor Freight has affordable EFI pressure testing kits like this one that will fit most applications: https://www.harborfreight.com/basic-fuel-injection-service-kit-64939.html.) The Chrysler/Jeep adapter to a Schrader valve is Mopar part number 83501572. I'm certain this adapter is only available used (maybe eBay) or as an NOS part (again, try eBay). There is likely an aftermarket equivalent if you can determine the TBI port thread size. A Schrader type fitting would enable quick testing at any time. AMC and Chrysler should have made this adapter a permanent part of the TBI assembly. This is a common test method for EFI/MPI fuel rails. You can see how the connector replaces the TBI test plug in this illustration: This is an illustration of the Mopar 83501572 adapter (or aftermarket equivalent) that works with an EFI Schrader valve test kit. This illustration is listed in the Mopar parts catalog for 1988 Jeep 2.5L YJ and XJ engines and used on other applications of the AMC/Chrysler/Jeep 2.5L TBI engines. Aftermarket Schrader valve adapters and EFI service kits show up at Amazon and elsewhere. Make sure the Schrader is rated for fuel use. If you can find an adapter/fitting that will fit the TBI test port thread, you will need a coupler to connect the adapter to your gauge. Otherwise, the pressure tester that you purchased can be used by installing a temporary brass or steel "T" fitting between the fuel supply line and the TBI unit's fuel inlet fitting. The fuel would flow from the fuel supply line to the TBI unit through the brass or steel "T"; the third port of the "T" goes to your gauge. You may need the "T" plus a few extra fittings to create this "adapter". You can even set up this temporary "T" at the engine side of the fuel filter if that's easier or preferred. The results should be close enough. If the return line to the fuel tank is not obstructed, you should get the same pressure reading at this "T" as you would get at the test port. Why? Because the TBI regulator lowers the available fuel pump pressure by continuously flowing excess fuel to the fuel tank via the return line. The pressure reading at the "T" should be in the 14-15 psi range when the fuel pump and engine are running. You mention not having an adjustment screw on the regulator's base. Illustrations in the 1989 FSM show a recessed screw that may not be readily visible. If you have a small mirror, see whether you have a screw that is flush or inset at the base of the bowl. If not, as you suggest, the Mopar parts catalog shows a replacement regulator that has a preset spring tension and a ball holding the spring in place. It looks like the illustration below and does not have the threaded adjuster screw shown in the FSMs. The spring and ball set a fixed adjustment on the fuel pressure regulator. There may be aftermarket versions that do not use the ball and have the smooth bowl you describe...That spring is inside the bowl or there is no lower (smaller) spring at all? In the design below, the small spring either sets a fixed pressure or acts as a damper—or both: As long as you're getting the 14-15 psi at the adapter "T" between the fuel supply line and TBI unit (or at the engine side of the fuel filter), you should be good. If pressure is as high as the fuel pump pressure, or well above the 14-15 psi, check the return line flow into the fuel tank for an obstruction. Once normal TBI fuel pressure is confirmed or reset, I would check the TPS (throttle position sensor) setting. The TPS is adjustable and should be adjusted to the voltage settings found in the FSM. Many owners and technicians mess around with the TPS to get a stable or desired idle. The TPS is like a rheostat switch and must have the right voltage settings and readings for each angle of the throttle valve. Often, adjusting the TPS to the right voltage outputs at the specified throttle valve angles will reduce or eliminate an over-rich or a lean fuel mixture. I would also check vacuum line routing to the EGR valve and test the EGR valve function directly, using a hand vacuum pump attached directly to the EGR valve with the engine idling. The EGR diaphragm can be tested for a leak with the hand pump and gauge. There should be a distinct effect on the idle when the EGR valve opens and closes. If the EGR diaphragm will not hold vacuum, replace the valve. If the EGR is original and not responding, but it does hold vacuum, I would remove the valve and either clean its exhaust ports or replace the unit. I clean an EGR by soaking the metal base and valve plunger in carburetor cleaner then removing carbon. (A soda blaster might do a reasonable job on light carbon or scale.) Do not allow carburetor cleaner to get into or near the diaphragm. Carburetor cleaner will warp or destroy a diaphragm. Let us know your findings... Moses