AZJeff

That wiring is a COMPLETE disaster, and needs to be fixed before you deal with the refrigerant plumbing.

Go to a real auto paint supply place. AutoZone and the like are not going to have touch up paint for a 30 year old car, no matter what brand of vehicle.

You can fix that tilt wheel aggravation with a little time. Check out this site: http://www.chevyasylum.com/column/tiltcol.html Since you have a GM steering column, the procedure applies to your Jeep as well as it does to Chevy's

If the resistor coils get corroded, that is no big deal. If the CONNECTIONS to the coils get rasty, then you have issues. The connections on the "outside" of the heater box, in the passenger compartment, should be relatively immune to moisture that causes corrosion, assuming you are not submerging your MJ/XJ to the point of water getting into the heater box. One KEY issue to consider is the fact that old resistor packs, when they get hot, cause the temper (springing-ness) of the female half of the "spade connectors", which are part of the wiring harness, to become loose. Any resistor pack that has seen excessive heat should be considered a candidate for replacing the female spade terminals on the wiring harness on general principles.

Some more modern cars use a semiconductor regulator to control fan speed, instead of just a plain voltage dropping resistor. Then again, those are a LOT more expensive than the simple resistor network the MJ/XJ. Heater uses.

They are all the same for MJ and XJ vehicle front doors. It’s a Dorman 924-148 for the check. It’s on Amazon. several makers offer the bracket and pin on Amazon as well

That looks great. A side benefit of late model XJ windshield trim is there is no chance for rust around all the stupid clips that hold the bright garnish molding on.

Backfiring is usually a sign of a lean mixture.

The door checks themselves will wear out on XJ/MJ vehicles and start making poppin noises. The fix is a new door check, and probably a new bracket where the check arm attaches to the “A” pillar. New door checks can be had from several sources.

Pete M is giving you the most methodical approach to finding the source of the DW. It's less expensive than just hanging parts at random until you find the culprit. When you follow his suggestion and have your friend saw the steering wheel, it sometimes helps to place your hand around each steering joint. That way you can feel actual motion between the two parts of the joint. You can also do this at each end of the track bar. It's kind of hard to inspect the bushings on the OEM control arms, so they might need to be removed (one at a time) and visually inspected and replaced as needed, but I would do that as a LAST step.

I am going to retract my previous statement about not replacing lifters. I found a website where a Jeeper replaced lifters sucessfully without any adverse effects. If you cannot clean the lifters (or it's too much of a PITA), then new lifters is probably not a bad idea after all. And now I understand why you called them "studs" They are actually double ended bolts. The head portion is a permanent part of the threaded shank, which makes them a bolt instead of a stud and nut.

LOTS of good points here. If the oil supply is good (clean pan and good pump) I would look for piston slap to be the noise source. My 4.0 will slap on a hot restart for 30 seconds or so, in spite of clean lifters (with a new head) and more than adequate oil pressure. The slap goes away (mostly) once the temperature stabilizes again, and does NOT get louder once the engine comes off idle. i forgot about theBD motor mounts I put in one of my XJs—-if you tighten the center bolt to spec, the engine will shake the chassis like all get out. And DO NOT buy the ones with a urethane isolator—stay with the rubber ones.

You can remove and clean the lifters (and put them back in the same holes they came out of). If you have lifter tap, how sludgy is the engine to begin with? Are the oil passages all gunky? 195 is what is intended to achieve the leanest burn for emissions. It also extends spark plug life and reduces carbon buildup. Don’t trust the temp. Gauge to be accurate. It may actually be running at a temp higher or lower than indicated. i will defer to others about any 4.0 with studs/nuts in lieu of bolts, as that is new to me. Yes, the through bolt is the pivot bolt.

Yes, a voltage drop WILL generate heat, assuming a constant current condition (which is usually the case).

I would NOT recommend changing the valve lifters unless you are changing the camshaft as well. Each existing lifter and it's matching cam lobe have worn into each other quite nicely, and changing one half of that now "mated" pair can invite trouble for the already used half (the camshaft). DO NOT use a 185 thermostat. The engine (and all associated emissions systems) were designed to run at 195*. By the way, you say "head studs" in your post. I was unaware of any of the years of the 4.0 in OEM trim that used anything but those special torque-to-yield head BOLTS. The brackets that attach the motor mount to the block are torqued to 45 ft-lbs. The ones that attach the mount to the bracket are as follows: 30 ft-lbs for all fasteners EXCEPT the mount through-bolt, which is torqued to 48 ft-lbs.

Not true. High current plus high impedance WILL translate to high heat at the interface of the two surfaces.

Not only may it not charge the battery, but it might create a high resistance connection that will lead to overheating of the connection and a possible fire. Fix the loose terminal to avoid a “carbacue”

Yeah, I know that is the case in most states. However, here in AZ, there are PLENTY of areas out in the boonies where you want all the light you can get. So my aux. lights are set up so that I can switch on the high beams, the light bar above the front bumper, and some driving lights mounted on the bumper. It probably violates state law about maximum candlepower, but I also use them intelligently--out of the open road with no oncoming traffic. But we all know of nimrods that run around with all sorts of auxiliary lights that blind other drivers, as well, so there is THAT consideration.

When I run auxiliary lights, I prefer to tap into one of the front parking lights for control line power for the relay. That way I can run the aux. lights any time the parking lights OR the headlights are on. Just another way of looking at things.....

More questions/suggestions to help narrow it down: 1. you say "take it out of gear." Does this mean just push the clutch in, or actually shift to neutral and release clutch? Do this both ways and report results. 2. additionally, when you push clutch in (and leave it in gear), rev the engine to the "magic" 2K to 2.5K range, and see what happens. They do the same with the trans in neutral, and the clutch engaged.

What happens if you shift to neutral and let the engine drop to idle while it's making the noise at highway speeds? Does it go away, or stay the same? That test will tell you if it's driveline or engine related.

Nice work on writing up the facts that most Jeep owners don’t understand about their HVAC system👍

I had this problem on my 1991 F150 when I owned it. I ended up drilling out the rivets that attach the aluminum arms to the steel mounting brackets, and replacing them with stainless steel bolts and “nylock” nuts.

I might be wrong, but I am pretty sure that if anyone had found a taillight housing that would fit into the existing MJ space (without welding/cutting), it would be all over this forum. Until someone figures that out (or comes up with some kind of "drop in" adapter that allows the use of smaller taillight from another vehicle), using old MJ used taillights of varying condtion is the only option. If I was desperate for new taillights, and couldn't find any decent ones for an MJ, I would save my pennies and have the bodyshop weld up the existing opening to take XJ taillights. I figure that would cost $1000 or more, including paint, so it's a true act of desperation.

I agree with this assessment. The complexity of welding in a large irregularly shaped piece outweighs the benefits.