1986 Jeep Cherokee 2.5L Low Speed Lack of Power

[Lowell]

I'm at my wits end troubleshooting my lil 2.5L engine.  I googled and found your page from about a year ago.  1990 jeep wrangle 25l engine timing.

Today I thought about timing.  It misses, like running on only 2 cylinders when at low speed and and only pulling slightly.  As I move into mid and upper rpm range it stops missing.  I still do not have much acceleration but at least it stops missing.  I've check and/or changed every sensor it has.  TPS is only rough since I have not gotten my laser tach to work yet.  

In checking fuel I have only 10 psi so I know that's a problem.  This started about a month after the SMOG guy changed the O2 sensor to pass smog.  I've check the voltage when hot and it's within spec.  I also had massive exhaust gasket leak so I cleaned the surfaces and replace the gasket.  

I'm a machine mechanic from way back in the Navy so I'm not just a new mechanic.  I just can't quite figure this one out.  I'll check timing tomorrow.

Lowell

[Moses Ludel]

Lowell, sounds like you've approached this logically...From what you describe, I'd start by remedying the fuel pressure and flow issue first.  If you haven't changed the fuel filter, try that before adjusting the fuel pressure regulator or performing any other fuel related work.  Make sure there is adequate fuel flow to the TBI unit and fuel return to the tank without any restriction.  Fuel volume is as important as fuel pressure.  Make sure there is sufficient volume.

The O2 sensor does raise questions, even if within spec hot.  I would check the O2 plug lead connections carefully and remove the sensor to see if its tip is contaminated or damaged.  If anti-seize got on the tip or you used a gasket sealer that sloughed off into the O2 sensor, this could be your problem and cause for strange performance.  The O2 sensor is sensitive to solvents and sealant compounds that are not approved for use around an O2 sensor.  

I've experienced strange performance issues with aftermarket O2 sensors.  I always use either a Mopar sensor or the OE supplier's actual replacement item.  (NTK is common on later Mopar applications, not sure who supplied O2 sensors to AMC in 1986.)  Aftermarket O2 sensors can otherwise be "generic" and fit a range of applications without being accurate for a particular engine.

If this is not going anywhere, I'd remove the crankshaft position sensor, clean it and test resistance.  Check the CPS connections, too.  

We'll go from there...Let us know what you discover.

Moses

[Lowell]

thank you for moving my message to a topic thread.  This problem started almost exactly one month to the day after it passed smog and was running great.

1. I checked the fuel return and it only reads 9 psi even after changing a very clean filter.  I change it only 2 years ago.

2. The O2 sensor was new in May to pass smog.  I know they are very sensitive.  It has a built in seal similar to spark plugs so I did not use any thread sealant.  I checked the plug to make sure it was clean and seated well.

3. I have not checked fuel volume, I wanted to check pressure between the tank and the filter first.  I'll do that in the next day or two.  Today I'm working on my sailboat.

[Moses Ludel]

The sailboat sounds like fun, Lowell!  You're on the right track to check fuel volume and pressure from the tank to the fuel filter.  The sock in the tank can clog, or the pump could be defective.  This is a sensible next move to at least rule out a tank or pump issue. 9 psi is way too low, regulated TBI pressure should be in the neighborhood of 14 psi at the test port.

Check the pump grounds while you're testing the pump.  Engine grounds are equally important. 

Keep us posted...

Moses

[Lowell]

Having read low pressure between the tank and the filter I ordered a new fuel pump.  In using the pump to empty the tank I noticed that the volume was terrific.  So, I put a gauge on and dead headed the pump.  Wow, 55psi.  I have a bad diaphragm in the pressure regulator.  Removing it the I could see it was defective and allowing bypassing.  I removed the throttle body and replaced it.  After adjusting I now have proper fuel pressure of 15psi read at the test port.  One problem solved.

Now I need to adjust the throttle position sensor.  It's dark so I'm quitting for the evening.

[Lowell]

Hooked up my friends Snap-On analyzer.  I'm questioning the ST & LT Fuel Trim

ST = 193-200   LT = 163   Are these normal?  The engine still misses when under load, both from idle and at driving speeds.

[Moses Ludel]

Lowell...2.5L TBI operates at 14-15 PSI (regulated pressure) while the Renix 4.0L MPI (1987-90) operates at 31 PSI once the engine is running and 39 PSI in engine cranking mode.  

On the 4.0L Renix MPI system, this is regulated pressure with a vacuum regulator dropping the pressure once the engine starts.  Limited vacuum during cranking prevents vacuum pull at the regulator, and the closed regulator raises the fuel pressure to 39 PSI.  Both the TBI and MPI systems have a return line to the fuel tank that must be unrestricted.

The pumps are different in output and should not be interchanged.  Compare the part numbers and crossovers to your existing pump.  Here are the 1986-88 2.5L TBI XJ Cherokee four-cylinder and 1987-88 4.0L Renix MPI inline six (XJ Cherokee) pump listings from Walbro.  See the "Learn More" and "Additional Information" at these links for specifications:

[1986-88 Jeep XJ Cherokee 2.5L TBI] https://walbrofuelpumps.com/jeep-cherokee-1986-1988-fuel-pump-4-cyl-2-5l.html

[1987-88 Jeep XJ Cherokee 4.0L]  https://walbrofuelpumps.com/vaf/product/list/index.php?category=%3F&make=7&model=40&year=2&engine=22

Both pumps look similar; however, Walbro rates the maximum output pressure for the 2.5L TBI pump at 17 PSI and the maximum for the 4.0L Renix MPI pump as 65 PSI.  Note that pinching the return line can cause a temporary very high spike in pressure, so a high pressure reading from this kind of testing could be deceiving.  I would compare part numbers between your new pump and these Walbro numbers.  Pump numbers are generally stamped on the housing of the fuel pump.

Walbro manufactures the fuel pumps (only).  If you need the Mopar part numbers for a 1986-88 Jeep XJ Cherokee 2.5L TBI application or a 1987-88 4.0L Renix MPI system, the Mopar numbers are:  

PUMP PACKAGE, Fuel - w/Fuel Injected Eng.
83502751 2.5L Eng.
04637192 4.0L Eng.

In 1989-90, Mopar went to a module that contains both the fuel pump and the fuel sender.  The 1986-88 models have the pump and gauge sender as separate components.

Moses

 

[Moses Ludel]

Missed your question about ST and LT, Lowell...Do you still have the original O2 sensor, the one that was replaced in May?  If so, try that sensor.  I'm still questioning whether the "new" sensor works properly.  Do you have a make and part number for the current O2 sensor?

The readings look very lean, does that sound consistent with your driving sensations?  What did your friend think?  Since he's able to get these readings, you apparently have OBD wire hookups to the diagnostics system.  Are there any codes?  How do the sensors read when viewed with the engine running?  Are you able to see the sensor readouts in real time?

This lean condition could also be a vacuum leak or an unseated or leaking EGR valve.  Check to be sure the EGR is not stuck open or malfunctioning.

Moses

[Lowell]

Fuel pressure: 2.5L engine ... 15psi fuel pressure read at the test port on the throttle body.  That was a problem because the regulator was badly leaking by.

Snap-on tester.  No codes, but I can read dynamic sensor reading.  When I told my friend what the fuel trim was he right away said vacuum leak so that's what I'm doing today.  Thank you, I never thought about the EGR valve  I'll check it as well.

[Moses Ludel]

Lowell...Many are surprised to find that the 2.5L TBI engine has an EGR valve.  EFI most often eliminates EGR, especially multi-point EFI (MPI or SMPI).  The Renix 4.0L sixes and 2.5L TBI fours do have EGR.  1991-up Mopar MPI engines eliminate the EGR system.  Typically, we think of EGR as a necessity for a carbureted engine with a fixed timing conventional distributor or a feedback carburetor and conventional distributor that has electronic timing override features—like the BBD carbureted 1981-90 4.2L Jeep engines with an ECU.

EGR valves can clog with carbon and get sticky, even on TBI engines with reasonably controlled air fuel ratios.  While many consider TBI an "electronic carburetor", it's way more than that: the A/F ratios are infinitely more precise than a fixed jet carburetor or even a feedback carburetor with metering.  

You've got a gem in that early 2.5L TBI fuel-and-spark management system.  Let's keep it running properly...

Moses

[Lowell]

Right now I don't much feel like it's a gem.  I've blocked off the vacuum from the side of the throttle body and ran a separate hose to the MAP sensor.  While waiting for a new EGR valve I cut a piece of thin brass sheet and blanked it off.  It still misses and sputter when any kind of load is put on it.  I noticed the heater vacuum comes directly off the manifold.  Tomorrow I'll cap that, the, do a smoke test.  Oh, don't know why I've not done it before but I'll also hook up my vacuum gauge.

I checked a local Jeep 4x4 shop, who sounds really good with Jeeps.  I asked if he had an LR2 V-6.  He didn't but also discouraged me from swapping.  From what you wrote I guess you're opposed ti it as well.

More update tomorrow.

[Moses Ludel]

Lowell, your XJ Cherokee is good to go when you're through with this repair.  Keep the vacuum check going.  Also, have you verified actual volume (not fuel pressure only) of fuel returning to the tank?

Try my time-honored test of TBI fuel spray into the throttle body throat:  Take an induction timing light, hook it to #1 spark plug lead, and shine the flashing light down the air horn of the throttle body with the engine running.  Note the shape, volume and steadiness of the fuel flow.  You can experiment with engine speed.

The fuel spray coming out of the injector should be a uniform, neat cone shape.  If sputtering or intermittent flow, you have a fuel supply or actual injector issue...

As for a 60-degree V-6 swap, the 2.8L came with two crankshaft designs, the earlier one was small journals with an archaic rear main seal design.  Crankshafts often broke from nothing more than the tension of engine driven accessories under load.  (I worked as a G.M.C. truck dealership line tech in 1983-84 and witnessed this phenomenon firsthand.)  

G.M. increased the journal size and went to a one-piece rear main seal that worked, then went one better and stepped this engine to a 3.4L displacement.  A crate replacement became available in the '90s that was a "bolt-in" replacement for the 2.8L.  

Not sure whether that G.M. 3.4L crate V-6 engine is still available, doubtful, it's older technology now, but a 3.4L 60-degree engine might be available from a RWD vehicle.  The crate engine would accept the 2.8L V-6 carburetor intake, which was a big plus.

Bad news for Jeep was that AMC bought 2.8L V-6 engines from G.M. during the earlier design era with the weak crankshafts through 1984.  The V-6 2.8L 60-degree engine did undergo the crankshaft change in 1985 for G.M. vehicles, and 1985-86 XJ Cherokee V-6s have the updated engine.  These are all Rochester 2SE carbureted engines.

Here are the Jeep XJ Cherokee V-6 block part numbers, which account for the better crankshaft and main seal in 1985-86.  The short engine listed has the better crankshaft and rear main as a replacement assembly.  These bigger journal short blocks went into 1984 vehicles under warranty:

BLOCK, Engine
83500707 1984
83502057 1985-86
83501875 1 (Short Engine)

Moses

 

[Moses Ludel]

Oh, boy, Lowell!  Timing chain and/or tension is shot.  Very delayed (retarded) valve timing.  That would drop manifold vacuum dramatically and retard the ignition base timing.  Let us know what you find, sounds like you're ready for a timing chain, sprockets and a tensioner assembly.

I would run a cylinder leakdown test on all four cylinders, each cylinder with its valves closed and piston at TDC despite your chain play...Confirm that the cylinders are sealing before doing a timing chain set.  Could be just the timing chain, sprockets and tensioner, or it could be the rings, valves and cylinder taper as well.  Separate issues before making the repairs.

Moses

[Lowell]

I did the rings and rod bearing a few years ago.  Out of 8 compression rings 6 were broken.  I few years earlier I had a valve keeper shear so while I had the head off I lapped all the valves.  When I did the rings there was NO ridge at the top, not even a carbon ring.  I de-glazed and re-assembled.

Timing chain is going back in.  The adjuster was completely worn out and the chain had some slop.  I still don't quite understand the pdf manual page 63 because the timing gear marks were right on the money.  They had not slipped a gear tooth.  Could that later model engine time completely different than the 84/85/86 engines?

[Moses Ludel]

Lowell, the chain adjuster wear is common, it's very likely this is all that's going on...Think of the tensioner as pulling slack out of the backside of the chain.  So, in the normal pull direction, you can have minimal timing variance without the engine running.  This is unloaded and with the crankshaft simply pulling the chain taut between the two sprockets.  Now envision the slack on the backside becoming play as the crankshaft rotates with force and momentum.  The slack  may influence valve timing variation or "play".

You're changing the sprockets and chain to be sure.  Measure the old chain for space between pins, you may discover that the valve and distributor timing error is partially from the tensioner wear.  It's generally, however, the chain stretch or space between the chain pins that creates valve timing error.  Make sure the ignition timing is correct after starting the engine.  

If you need any pointers on aligning the 2.5L valve timing marks, let me know.  Otherwise, share how much of a difference this renewal of parts makes...

Moses

[Lowell]

There was a wear mark on the timing cover.  Turns out the harmonic balancer rubber is old, hard, and coming out so I have a new one on order for Monday.  It was also a great time to install a new seal.  I never would park in people's driveway because of the constant oil drip from the front seal.  I did the rear seal when I replaced the clutch 6 years ago.

[Moses Ludel]

Lowell...Cover off, yes, time for the new seal!  You mentioned timing marks on an AMC/Jeep 2.5L inline four.  I have the July 1985 revised, the 1989 and the 1994 official/factory shop manuals.  There is often confusion about aligning marks on the 2.5L (actually the 2.46L/150 AMC four) engine.  

First off, you align the two stamped timing marks on the camshaft and crankshaft sprockets by facing them toward each other (inside the chain, the camshaft stamped dot at 6 o'clock, crankshaft dot at 12 o'clock).  With the stamped dots inside, between the sprockets, confirm their alignment with a straight edge placed through the center line of the camshaft and the crankshaft snout.  This establishes an accurate angle of view or reference point.  Make sure there is no chain slack at the "pull" side of the chain.  Rotate the crankshaft in its normal direction of rotation to bring these marks into alignment without putting slack in the timing chain.  

Notes and cautions: Do not rotate the crankshaft backward (counterclockwise when looking at the front of the engine), or this will put slack in the chain and throw off the mark alignment check. It is assumed that a technician/mechanic is not rotating the crankshaft and camshaft much at all, since the valves, lifters and rocker arms are still in place; if the rocker arms and bridges are not removed, you don't want to ram a piston into an open valve by rotating the crankshaft with the sprockets and chain loose!  (In your case, since you removed the rocker arms and bridges, the valves are all closed, and there is no risk of pistons interfering with the valves.)  This is just a sprocket and chain replacement, and the best method is to align the marks on the old chain and sprockets before removing them.  Then carefully remove the two sprockets and chain as an assembly; install the new chain and sprockets the same way, without disturbing the crankshaft and camshaft positions.

Then there is the "verification" timing check, which is explained using different clock positions over the years.  Roughly, the crankshaft sprocket mark is placed at 3 o'clock with the dot-marked tooth engaging the chain.  There should be 20 chain pins between this sprocket tooth and the tooth on the camshaft where the camshaft's marked tooth engages the chain.  This is a 20 pin count at the right side of the chain when looking at the front of the engine.  The 20 pin count is between these two marked sprocket teeth.

So, why the verification check on the 2.5L and not the 4.0L or 4.2L inline sixes?  Because the 2.5L uses a chain tensioner and the 4.0L or 4.2L engines do not.  The concern here is true valve timing.  The most accurate verification is the actual number of chain pins between the two marked sprocket teeth.  With the tensioner, there could be confusion if there is any slack in the chain when aligning the two dots face-to-face.  By measuring with the sprocket teeth engaged in the chain, you get a double check verification, which makes sense.  

Moses  

[Moses Ludel]

Lowell...Here is how the timing sprockets are aligned and how to verify valve timing on your 1986 Jeep 2.5L TBI engine.  The information is from the 1989 Jeep® FSM.  The procedure is similar for all years of the AMC/Jeep® 2.5L/150 four that use a chain tensioner:

Jeep 2.5L Valve Timing Check.pdf

Note that the 20-pin check is proof that the timing marks and teeth are set properly...

Moses

[Lowell]

Monday ... all back together.  New timing chain.  Engine vacuum at idle doubled . .. but :-( the engine still misses, I think only on 1 cylinder, but when you only have 4 it's quite pronounced.  I didn't do the 20 pin check but I check and re-checked several times the dot alignment with a straight edge, both before and after the tensioner was installed.  Before, I took up the slack with my hand.  With 22-24 "hg at idle should I still make a smoke machine to check for vacuum?  I'm really at a loose to what the real problem is.

All sensors checked and rechecked, Replaced intake air sensor, crankshaft position sensor, throttle position sensor (even though both checked good) EGR valve, fuel pressure regulator, timing sprockets & chain /w tensioner, Harmonic balancer (probably not contributing to the problem, but worn out).

Do I go more complex in my diagnosis or am I thinking this too deeply and I need to go shallow and look for the obvious ?????  .... Hmmmmmmmm

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[Lowell]

Tuesday ... Verified the distributor angle was correct at TDC ... yup, 6 o'clock.  What next??  I ohm checked the coil - ok.  On inspection of the ICM I noticed that the bottom, where to rubber is poured in, was all dried and had many cracks.  ???Could be???  It's only money so I replaced it.  :( no change.

Removing one plug wire at a time I concluded that the missing is on #1 & #4 cylinders.  Could it be a fuel delivery issue?  Injector seems to be spraying a nice pattern.

When at idle I have 22"hg.  When I tromp on the throttle it dropped to 3-5"hg.  Is this normal?

Just finished performing the injector spray test with an induction type timing light.  I can't really see any spray pattern ... at all.  When I shine a flashlight in the throttle body I can see that the butterfly is wet and fluid is moving but even then I don't see any type of conical pattern.  Having never see one that I know is working properly, I mean how many people look down the throttle body when everything works perfectly, I'm not really sure what a normal spray pattern even looks like.

Tuesday afternoon:  Update ... so, I replaced the fuel injector nozzle ... :-( ... no better and no worse.  I'm running out of parts to check or change.

[Moses Ludel]

Lowell...Another approach with the TBI spray pattern would be a timing light spray pattern test with the light tried on each of the cylinders.  You need to see some kind of conical spray pattern to know what is normal.  #1 should be the full pattern, which should also apply with #4 cylinder (opposite in firing order).  Each of these two cylinders would rely upon the #1 cylinder TDC reference from the crankshaft position sensor, which takes us back to a dirty or defect CPS, loose or resistant wiring to or from the CPS, or the ECU/ECM not processing the TDC signal properly.

Footnote:   You may not be seeing a fuel spray cone pattern because the ignition spark lead is 1) too weak to strobe the timing light, or 2) the spark timing degrees could be so far off that the injector spray pattern is out of sync with the #1 spark plug firing.

Recap your troubleshooting with regard to each of these issues.  If you're not seeing a spray pattern at cylinders tied to the CPS signal for TDC, there's a problem.  Have you tried unplugging and replugging the ECU/ECM to confirm good continuity?  Have you checked grounds to the body and ECU/ECM for too much resistance or an open ground?  Run an ohms resistance test from the body ground(s) directly to the negative post on the battery.  

If you have a decisive miss under load, it's possibly a ground or ignition fault.  If you have an induction timing light, try hooking the timing light to each cylinder's spark wire lead, one at a time, and watch the strobe light carefully for flash consistency at each wire.  If missing or dim, there's a primary or secondary ignition issue.

Ohms check the spark plug leads (end to end with the wire disconnected), the engine could be spark misfiring under load.  If you've already checked the ignition coil for ohms resistance, check the distributor cap and rotor for carbon tracking and other causes of a miss or short to ground under load.  

On a distributor ignition like yours, the coil high tension wire is often the culprit if all cylinders suffer under load. Check the coil to distributor cap high tension lead for ohms resistance, it's a fairly long lead on this engine, making it even more prone to break down under load.  Twist these high tension and spark lead wires gently in loops when testing for opens...Keep in mind that all four cylinders fire through the coil to distributor cap lead, that's four times the service and wear over time.

We'll go from there...

Moses

[Lowell]

 

The original problem was probably just a worn out fuel pressure regulator diaphragm.  It was bypassing enough that I only had 6psi fuel pressure at the throttle body.  However, in the process I also changed out plugs, wires, cap, & rotor.  This meant I got rid of the Bosch cross-fire plugs I'd been running for years and put in the oem plugs.  I think I just exchanged problems.  I fixed the fuel pressure problem but introduced a plug problem.  It was misfiring badly  and consistently on #1 & #4.  The plugs were brown and dry.  My thinking was that the computer was seeing unburned fuel at the O2 sensor so it leaked out the mixture.  Today I did about 4 hours research on plug heat range and found many articles stating that an improper heat range can cause, among other things, misfire.  Remedy???? ... hotter plug, but which one since most plugs these days don't display the heat range.  The tech agent at www.sparkplugs.com was very helpful in helping me find a plug that was one heat range hotter with the same tip configuration as the oem plug.  I'm not running oem plugs on #2 & #3 and NGK ZFR4F-11 4043 on #1 & #4.  NGK heat range is backward.  Low numbers are hotter.  The oem plug was a heat range 5.  I installed the two plugs in the parking lot and drove down the back of the shopping center.  No misfire, no hesitation, just good clean acceleration, even in 2nd gear from idle.  ...  But look at it this way.  I needed a fuel pressure regulator,air temp sensor, EGR valve timing chain, front seal, harmonic balancer and it probably didn't hurt to change out the other electronic components that were probably 30 years old.

It's been a steep learning curve but a great challenge and very educational.   ...  hotter plugs, but only on 2 cylinders .. who would have guessed???

[Moses Ludel]

You actually did a thorough and thoughtful troubleshooting job, Lowell.  I agree that the parts replaced were in no way "good money thrown after bad".  You've increased the longevity of the engine, restored the TBI system and refreshed the fuel supply system.  The vehicle has better day to day reliability.  

As for the simpler spark plug heat range solution, I was aware of your comments on doing a complete tune-up and did not consider the spark plugs.  Eventually, however, we drifted back to the ignition.  You had simply done too much work for the problem to be anywhere else.  I considered a defective ECU/ECM but thought it wiser to send you back down the spark plug cable and coil lead path.  The spark plug heat range was a good angle on your part!

I've seen carbon core spark leads fail right out of the box, new spark plugs break down on ohms reading tests, there have been spark plugs that failed to fire properly under compression loads.  In the last five years, I installed a non-OEM O2 sensor and TPS switch in our '99 XJ Cherokee 4.0L and both parts failed to perform on specification.  I quickly installed a better TPS and an OE equivalent NTK O2 sensor.  The market is rife with poor grade aftermarket replacement parts.

If your fuel pressure is normal at the TBI test plug and the spark plugs have light brown to light gray coloration without any carbon buildup or signs of oil fouling, the hotter plugs should work.  I do run NGK or Bosch OE replacement spark plugs in Jeep engines successfully.  AC plugs are good as well.  I've avoided Champion plugs for decades.

Pleased that you solved the riddle, congrats, much easier than a 60-degree V-6 swap...

Moses

[Chris Caronna]

Just bought a 86 Cherokee Pioneer with the 2.5 l TBI. I'm having the same problem at idle. I'm sure this info will help. I'm going to buy the NGK plugs today. Not knowing any better I just took the Champion plugs they gave me for the tune up. 

[Moses Ludel]

Good  vehicle to restore, Chris.  There's a wealth of 2.5L TBI troubleshooting and service info available at our forums, glad you joined.  I have the factory AMC/Jeep XJ Cherokee Workshop Manual in my library, handy info when you're stumped.

So, is this a 5-speed and 4WD?  The engine can handle the weight if you do not get carried away with weighty accessories.  Oversized tires will demand axle gearing changes.  Let us know your plans.

The XJ is just fine with the 2.5L four.  The GM 173/2.8L V-6 was in poor form during 1984-85, though 1986 provided the larger journal crankshaft, which made the 2.8L V-6 a decent (though not world-beating) engine.  Owners of the 2.8L V-6 models can benefit from a 3.4L replacement V-6 engine, which GM offered at one time as a bolt-in long block replacement engine/crate motor.

Moses

[Chris Caronna]

It's the 3 speed automatic with 4WD. The motor mounts are shot so I ordered those along with a gasket kit, and several other exterior engine part's. I'm not doing anything till I get the motor mounts in. I know it leaks at pretty much every seam and probably shook itself apart.  I did a basic tune up, plugs, wires, filters (air and fuel), and coil. I can't tell if it's a valve, rod, or a exhaust leak at the front of the engine. Could be a gasket but reading the tread, it could be the timing chain. I also a have a mystery hose that was cut off. It's located just to the rear of the valve cover on the drivers side (not attached to the valve cover).I don't have a place to pull the engine so I plan on removing the radiator  to work on the front end of the engine.

But this jeep has been in many different garages so it's pretty messy. Nothing in the gauge cluster works except the voltage. 

As far as tires, yes I think they are too heavy. 32s on heavy rims (15X10). I plan on replacing those and installing an electric fan to lighten the load on the engine. The AC is R12 but still works great.. Being in Arizona AC is important so that is staying. The interior is about an 8 out of 10. Upholstery is 9.5 on a 10. Thanks for being a resource, I will be on here a lot I'm sure.  

[Moses Ludel]

Your sense of humor will take you far with this XJ Cherokee, Chris!  The transmission (999/904 Chrysler type unit) at the very least will need a band adjustment and fluid/filter service.  You'll be able to tell its condition by the oil pan debris.  Share photos in a new topic, I'll be happy to read the "tea leaves".

I've converted R12 to R134 with great success.  Our '87 Grand Wagoneer with a York compressor "spit out ice cubes" on R134.  You'd be very happy with the changeover if done properly using conversion kits, O-rings and a complete vacuum down of the system plus a new expansion valve.

Keep us posted, start your own topic, this early XJ Cherokee deserves attention!

Moses