Eagle

"Fits many models" is not much of a description. If it's for full-size trucks, there's no way it could fit in a Comanche (or Ranger or S-10). Aside from that, it's ugly, and it's not a roll bar. It's a show bar. No structural integrity whatsoever.

I would opt for a '94. No air bag. Two problems eliminated. The difference between a '94, '95 and '96 is going to be more a question of what you can find -- they are ALL pretty old by most people's standards.

We have to see the back of the tach circuit board to tell if it has the potentiometer. Based on the design of the speedo dial, I suspect you have the early style cluster, which does not have the potentiometer.

3" or 4" lift on the front with the rear at stock height will look ridiculous. That's my opion. I agree completely. It will also make it handle atrociously.

There should be no adjustment needed when using a 4-cylinder tach in a 4-cylinder vehicle. Even if the tach came from a 6-cylinder, it wouldn't be that far off. The tach counts ignition pulses. The 4-banger has 2 pulses per revolution, the 6-cylinder has three. So let's say your engine idles at 1000 RPM (it doesn't, but it's simpler to visualize.) A 4-cylinder will then generate 2,000 pulses for 1,000 revolutions. A 6-cylinder will generate 3,000 pulses for those same 1,000 revolutions. So if a 6-cylinder tach is calibrated to read "1,000" when it sees 3,000 pulses, stick it in a 4-cylinder where it sees only 2,000 pulses and it'll read "666" RPM. Check the rear of your tach to see if it has the calibration potentiometer. Even if it does, it may not have that much adjustment in it. I suspect your "new" tachmoeter may be defective.

The Renix system controls both ignition (which a diesel doesn't have) and injection. The injection is calibrated to maintain an optimum air/fuel mixture for gasoline, in a 4.0 liter gasoline engine. Basically, regardless of whether it's a Renix system or a newer Chrysler system, none of the engine controls will be usable for a diesel conversion. You will have to get the injection and controls with the engine, and figure out for yourself how to integrate it into the chassis wiring harness. Not even the tachometer will work, since the Jeep tach operates off the ignition signal, and with a diesel there is no ignition.

Remember that the Renix system uses a different flywheel and CPS than the Chrysler system. The flywheel and CPS MUST match up with the vehicle's electronics.

A ZJ 4.0L engine will bolt into an MJ just fine. BUT ... The question is about using it in an '88 MJ. The '88 used the AMC/Renault Renix injection/ignition system. That went from 1987 through 1990. Chrysler introduced their own injection/ignition system in 1991, and that's the same system that was used when they introduced the ZJ in 1993. So, to use a ZJ engine as it sits, with the ZJ ignition and injection, will require significant rewiring. If you use the ZJ engine as a short block, or even a long block, and swap over the electronics and injection controls from the old engine, then you can drop the engine into a Renix MJ.

XJs and MJs are what we do here. DO NOT drop your cross member in an MJ.

Not just the air conditioning. All the flapper doors that control air flow for both heat and a/c are operated by vacuum. Yes, you NEED to connect those vacuum lines.

Modern automobiles NEED a thermostat to run properly. Many people simply don't understand that the purpose of the thermostat is to keep the temperature UP, not down. A properly-functioning radiator and cooling system are capable of keeping the temperature well below the temperature needed for optimum combustion -- in fact, often below the minimum temperature for the electronics to switch over to to closed loop operation, meaning the system is reading and reacting to all sensor inputs. For the Renix-vintage Jeeps, that switch-over takes place at somewhere between 170 and 180 degrees F (I used to know more exactly, but I haven't thought about it for a long time). Removing the thermostat could have you running in open loop mode all the time. The vehicle will run ... but it will be always running on a pre-mapped air/fuel curve that's far richer than optimum for an engine at normal operating temperature, and the fuel mileage will suck. Removing the thermostat is NOT a fix -- it's a temporary bandaid that just masks the symptoms of an underlying problem.

Oxygen sensor?

I burp mine, and I learned how to do it from a racing buddy who was a Jeep shop foreman and service manager when my '88 was bought new. I do it so I won't have to remember to check the coolant level later, but it's not a big deal and I'm sure most shops don't (didn't) do it. Back to your original post and overheating. You may still overheat after replacing the coolant bottle and cap. If your truck doesn't have a fairly recent radiator, it's probably clogged and not doing a lot of cooling. You reported that there was no thermostat -- people typically remove the thermostat because they think that's a "cure" for overheating. It's not.

That's interesting, considering that they didn't use the AX-15 in either 2000 or 2001.

Fill it (to the halfway mark, as indicated), then drive it. Check it after it cools down, and add coolant as necessary.

You are aware that there are TWO sets of crossmember mounting locations on the frame rails ... right?

That's why everyone says they want to go higher, but you have to consider where your tires are rubbing, and then look at whether a lift (or MORE lift) can possibly do anything to alleviate it. You haven't mentioned (or I missed it) how wide your tires (and rims) are. You said 32s, so I'm going to guess 32x11.50. That's a wide tire. I ran 31x10.50s in factory rims on my trail MJ, and the inner sidewalls were VERY close to the rear leaf springs and to the inner fender liners. After every wheeling trip, the insides of the rear wheel wells would be polished and coated with black rubber from the tires rubbing as the axle twisted relative to the chassis. More lift would not have helped -- the problem was insufficient lateral clearance. Your wheels appear from the photos to be non-Jeep and to have less backspacing than factory rims, but then you're running much wider tires, so it probably evens out. So IMHO more lift isn't going to help in the rear. Where do you rub in the front? From the photos, I'm guessing that when you turn, the trailing outboard shoulder of the tire hits the lower corner of the front flare. Again, lift isn't the answer there. That's a mismatch of tire width, wheel backspacing and axle width to the vehicle. People don't like to believe it, but it has been proven that you can run 31x10.50s on a stock MJ (or XJ) with NO lift. On factory rims, the 31" tires tuck nicely into the fenders with no cutting or trimming of sheet metal at all. The only rubbing is the inner rear shoulder of the tire rubbing the lower control arm at full steering lock -- and more lift won't cure that, either. The cure is to run WJ lower control arms, which are curved inboard to allow more tire clearance. Now ... if you're in love with the look of a lifted truck, I can't argue with that. I can point out that it's a bad idea for a daily driver because it rides harsher and gets worse gas mileage, as well as being a PITA to get into and out of if you're wearing "dress-up" clothes, but it's ultimately a personal choice. I just don't want you to think you have to spend a bunch of money on a better or bigger lift in hopes of eliminating rubbing, only to find out that you wasted your money. I work for a living ... I know money doesn't grow on trees. Spend enough time to figure out your priorities and what you really need before you break out the Mastercard.

There's your problem. The surge bottle is NOT supposed to be topped off. It's an expansion tank, not an overflow recovery bottle. It should be filled to no more than the halfway mark when cold.

There's a pushrod connecting the ignition key tumbler to the ignition switch. Check adjustment.

There is no bushing kit. There are various bushings on various parts. The advice was to replace them "as you need them." That means look them over, and replace what needs to be replaced. The upper and lower control arms have bushings on each end. The LCA bushings are all in the arms, so if you plan to replace the lower arms, you'll be doing bushings then as part of the replacement. The upper control arms have bushings in the arm at the frame end, but the axle end bushings are mounted to the axle. Check those out, because those won't automatically be replaced if you go with aftermarket control arms. And don't get so hung up on height. A properly set-up MJ does NOT need a lot of lift to be off-road capable -- they are off-road capable in stock configuration. Especially if this vehicle is your daily driver and only sees occasional off-road use, you should be looking for the optimum configuration using the LEAST possible lift and the SMALLEST possible tires.

Photos? Of the chalk outline on the sidewalk?

It's an internal combustion engine. It only needs three things to start and run: Fuel, Air, and Spark. If it won't start, ONE of those three things is missing. Air is unlikely, since it's free and there's almost no way to NOT have air, unless you have a totally clogged air cleaner or multiple broken valves or lifters. So that leaves fuel and spark. You may have a new fuel pump, but is it pumping? Is the filter clogged? Is the fuel pressure regulator allowing it to build sufficient pressure for the injectors to inject? Do you know that the injectors are functioning? You may have enough spark to make it cough, but that may not be a strong enough spark to actually light off a cylinder full of fuel/air mix. One other possibility -- if the distributor has been worked on or monkeyed with, the timing may be off.

Never mind

My first guess is CPS. And, FWIW, a 4.0L does not have a 3-speed automatic transmission. It has a 4-speed AW4.

Not easily. A 2WD transmission has an output shaft and tailshaft housing to accept the slip yoke from the driveshaft. The tranny that mates with a transfer case for 4WD doesn't have the tailshaft or the tailshaft housing, it has a much shorter output shaft that mates to the transfer case, and a flange on the tranny case for the transfer case to bolt onto. All you need to do is swap over the transmission and transfer case from the donor XJ in tact. Don't even take them apart.