AZJeff

The clutch is just a electromagnet whose coil creates the magnetic field when 12V is applied. The fact that applying more voltage makes the clutch work is damnning evidence that the clutch coil is toast. You may or may not be able to obtain just a new clutch assembly, depending on which brand of compressor your MJ has. I am not reallly up to speed on which compressors they used back in the 1980's, so you might have to do some searching on line for a parts source.

Yup. Thirty year old grease, mixed with dust and other crud, makes the door latch and lock mechanism prone to sticking, as well as being hard to actuate to begin with.

THIS is most like the issue. Eagle speaks from experience, I am certain.

VERY good point. If you put in a large fuse, yet use (relatively) small guage wires, you wind up using the wires as the fuse element.

Acrylic is used for guage cluster lenses because it can be quite optically clear and yet easy to mold. Unfortunately, it is also brittle, and fractures in impact relatively easily. This is why it is a poor choice for headlight lenses.

The plastic for the gauges is acrylic, whereas headlights are polycarbonate. you can buy special plastic polish from Amazon intended for use on acrylics. I used that very successfully on my tail lights as well as gauge lenses.

The fan specification should tell you the current draw or the power draw (in watts). Take the wattage and divide by twelve (battery voltage) to determine current draw. Caution—startup surge current can be much higher than steady state current. Take the steady state current and add 25-30% to that when selecting a fuse. actually, I prefer self-resetting circuit breakers over fuses for cooling fans. Nothing sucks more than to be stuck by the side of the road because your fan won’t run because of a 25 cent fuse That failed due to fatigue.

Those flanges are a press fit onto the water pump shaft, and are designed to be an interference fit during manufacture. It sounds like the one you got is defective. I would expect something like that from Autozone or the like, but not from Mopar. Then again, no brand is TRULY without a defect now and then. You got lucky and won the defective part lottery from Mopar, I guess.

I have a combination 3rd brake light and bed light from a mid-90's Ford Ranger on my MJ.

This is debated CONSTANTLY on automotiive forums, because many people don't understand the function of the thermostat. The thermostat in a liquid cooled engine controls the MINIMUM operating temperature for the engine, NOT the maximum temperature. The maximum temperature is governed by the amount of airflow over the radiator, the condition of the water pump, the condition of the water jackets in the block, the condition of the hoses, and finally, the condition of the tubes and fins of the radiator. As others have mentioned, the OEM thermostat is a 195* item. That means normal operating temperatures should be around 200-210* when the engine is fully warmed up. I live in AZ, and my temperature guage is slightly off. It reads about 220* when it's really only about 212*, but I am not too worried, because that engine temperature is reached when the outside air temperature is 116* F. Yes, it really was that hot the other day

It's obvious you did truly did an totaly rebuild of the under-hood wiring, and I have a suggestion: if you put the entire harness inside a plastic corrugated loom, it will clean it up a bit (and protect it further.) Maybe you did this after this photo was taken,....if so, ignore my suggestion.

I used an electric fan in my old 1991 F150. My setup used the two speed fan from a Ford Taurus station wagon with the 3.8, and is a common, low-cost way to get some serious CFM across the radiator. On the "high" speed setting, the fan drew THIRTY (30) amps continuously. Needless to say, that's pretty darned high. Rather than rely on a fuse that might fatigue and fail (even if sized correctly), i used a self-resetting circuit breaker and #10AWG wire to the fan (which is what Ford used on the OEM installation.) You might double check your startup current AND your running current on those three fans in parallel. I am betting it is higher than you think.

VERY GOOD TIP to avoid radiator damage with fans that don’t want to come off easily!👍

I have owned Several XJ’s and an MJ with the 4.0, and all of them need hellishly high belt tension to avoid squealing. My approach is to Tighten the belt “very tight” based on previous experience, and then drive the vehicle from a cold start using the A/C to put the max load on the belt. Invariably, my tension is inadequate, and the belt squeals. So, I tighten it a bit more and try again. Sometimes I have to do this 2 or 3 times before I get the tension high enough. The point of all this is that even with a tension gauge, it’s best to do an “approach to zero squeal” to get optimum belt tension.

Good to know, thanks.

Agreed. The ball joint type upper end of the XJ/MJ track bar is one of the less-than-stellar parts of the vehicles design. Swapping it out to another approach is an improvement.

I would contact Rock Auto about any warranty it might have. If it hasn’t been submerged, two months is a pretty short life expectancy for a bearing, even if overloaded due to excessive belt tension

I am well versed on booster function tests, and I am certain my booster was functioning as intended. I remain convinced my old 1992 XJ brakes were marginal at best, and that the later booster is a significant upgrade. Caveat—I have never driven an MJ with stock brakes, but I cannot think they would be massively different than an XJ of the same era.

Rear discs never appeared on the MJ nor the XJ during it's production runs. Rear discs first showed up on the ZJ, and were back compatible to the MJ/XJ chassis due to extreme similarity.

I dunno. My first XJ sat on stock wheels and about the biggest tire I could fit without a lift, but I don't remember the exact size. That beast could NOT lock up it's brakes until I did the booster upgrade. I know your experience on the XJ/MJ chassis exceeds mine from the days when I lurked on XJ forums. None the less, there must have been a good reason Chrysler upgraded the booster design, and that is why I did it to my MJ when I got it.

Its interesting you say that, because my 1992XJ had HORRIBLE brakes, even after I rebuilt the drums in the back and replaced the calipers up front back when it was about 10 years old. I literally could stand on the pedal and not lock them up. I was new to the XJ/MJ chassis at the time, and read up on how Jeep had created the improved dual diaphram power booster and MC. I decided to put that in my XJ, and the improvement was quite noticeable. It's possible I had a bad booster before, but it didn't show any symptoms when I did the classic booster function test.

I will also add that early XJ’s (and their MJ cousin) don’t exactly have the best boost levels for their power brakes. The later XJ’s addressed this with a dual-diaphragm power booster, and I would consider this an almost mandatory upgrade when doing a brake system overhaul on these vehicles.

The cooling system on the XJ and MJ vehicles are, under the best of conditions, just barely able to handle the “worst case” heat load from the engine. It’s the Achilles Heel of the beast. Deterioration of system parts often pushes the system into the overheating mode. The older ones with “Closed” cooling system are even MORE sensitive to the deterioration issues. If you blew one hose, it’s a good bet they are ALL in bad shape. also, the pressure tank and it’s cap on the closed systems is prone to leaking and/or bursting with old age. Finally, you say you removed the t’stat. Was that in hopes of lowering cooling system pressures? If so, that is NOT going to fix the issue, as the t’stat controls the MINIMUM operating temperature once warmed up, NOT the maximum temperature. Stick a good 195* thermostat back in the system when you replace all the hoses. Lastly, what temperatures is your engine actually seeing when warmed up running at say, 30mph?

If you can’t get your impact in there, you can jam a short stout screwdriver though one of the spokes on the HB, and wedge it under the shelf of the engine block where the oil pan attaches. That will hold the HB while you use a breaker bar to free the bolt.

Mine is located there because I have a driveline from a 2001XJ, but moving it frees up space in the engine bay, and doesn’t cause any issues for the undercarriage if done well.