AZJeff

Given that any belt you obtain that is second hand is over 40years old, I would encourage you to purchase a NEW seat belt instead. The old fabric is probably badly sun faded and thus deteriorated and of low strength compared to new. There are LOTs of companies that make replacement seatbelts in colors that will come close to matching your interior. Do a search online.

On most unibody vehicles, the rocker panels comprise a significant part of the longitudinal stiffness of the chassis structure. That is NOT the case on the MJ/XJ vehicles, as they have a boxed rail under the floor pan that constitutes a type of integral frame rail down the length of the chassis. because of this, I recommend fixing the floor pans to increase overall longitudinal stiffness before attacking the rocker panels (which are more cosmetic on the XJ/MJ)

That is a good point. Due to me being in AZ, and having a Comanche that lived it's life in a relatively benign environment, I have never had those worries.

I cannot understand why a glass shop would not do work on an MJ "due to its age". The glass is attached to the body with the same urethane adhesive an almost all other vehicles. The only variation from newer vehicles is the use of the chrome trim around the glass/body joint, and that is merely held on by clips attached to welded studs on the body. As others mentioned, converting to the new style glass trim (97+ XJ type) eliminates the chrome trim pieces, and makes glass installation that much easier.

The AC system for the MJ is identical to that for the XJ, so the system is sized to cool the vehicle with the larger internal volume and greater glass area. This means that it’s actually oversized for the job in the MJ. Converting an MJ to use R134a will, in theory, will reduce its overall cooling capacity. In practice, the extra margin in the MJ’s AC cooling ability makes this pretty negligible.

Any time a heater core is found to be plugged up, it’s a sign that the cooling system has not been well-maintained somewhere in the vehicle’s past. That, in turn, indicates that the radiator is, at the very least, not in OEM condition (unless it was previously replaced due to blockage.) if I see a plugged heater core, I immediately assume the radiator is in need of replacement. The XJ and MJ series of vehicles are NOT tolerant of cooling systems that are in any condition except like new in terms of performance, as the design has VERY little margin for deterioration.

There is absolutely NOTHING wrong with a Timken bearing made in a facility other than the USA. Timken has had production operations in multiple countries outside the US, and they all build products to the same standard for that particular bearing. Any claims of evidence that Timken parts made in “country X” that is not the USA is strictly anecdotal, with no statistical backing to such claims.

If you use a Remflex manifold gasket, they recommend tightening the bolts/nuts to a specific amount of gasket COMPRESSION, rather than fastener torque. this means conventional sockets/ratchets/ extensions can be used to install the manifolds and the Remflex gasket. No torque wrench needed. best of all, they won’t lead like OEM style gasket.

Here is what one of the Oracle lights looks like installed on my MJ.

I did a set of Key Parts lenses, and they are HUGE improvement over chalky 40 year old OEM ones. However, the original taillights on the MJ are pretty lame in terms of brightness, especially in daylight conditions. I have this overwhelming fear of some idiot here in AZ not paying attention and running into the back of my truck. With that in mind, I forked out the coin for the Oracle lights, and could not be happier, as they are markedly brighter than the OEM ones.

I have only seen pictures of a pre-1997 heater box disassembled, as the only ones I have ever torn apart came from 97+ XJ's. From what I remember, the actual heater box on the later design is physically different than the earlier design, which means the heater core and evaporator cores probably are different as well. Renix heater/evaporator cores should be the same as the later (pre-97) ones, as they did not change the heater box, to the best of my knowledge, and that would make the suggestion of@eaglescout526 viable.

Are you trying to use the evaporator from a 97+ XJ in your MJ? If so, doesn’t that require the use of the corresponding heater box?

With factory ride height suspension, you will need to undo the lower front shock attaching points to allow the axle to drop further and allow the oil pan to come free. Once you have 3 inches or more of suspension lift, dropping the front shock mounts is not needed to get the pan out, but it makes it easier the more axle compliance you can get

Does anyone have a line on a source for a Crank Pos. Sensor for a 2000XJ with a 4.0 (that's the engine I have in my MJ). The scuzzy aftermarket one I put in a few years ago has croaked, and I want to buy a "REAL" one this time. I am hoping some Mopar on-line store has them. If anyone knows the current Chrysler part number for that item as well, it would be appreciated.

It is NOT a brake fluid level switch. It is a brake pressure IMBALANCE switch. The factory brake system is divided into two subsystems—one for the front wheels, and one for the rear wheels. Basically the switch closes when either of these subsystems have lower brake pressure than the other, which can happen if either system develops a leak. The switch is very basic, being just a plunger that is activated by a spool valve that shuttles one way or the other when pressure on both sides of the spool is not equal. the switch is common to many vehicles of the era of the MJ. I would bet ALL Jeeps of that era share a common part here, along with the Fords that were mentioned.

I am skeptical of the effectiveness of radiator flush on a rad that has built up crud over years of neglected coolant. It’s been my experience that the relatively small long coolant passages in a rad are a bit like advanced arteriosclerosis, where the crud grows upon itself and cements itself in layers, plugging the passages such that nothing short of mechanical cleaning of the tubes will remove the crud. I am old, so I remember when radiator shops would do what was called “rodding out” of an all metal radiator. This involved unsoldering the tops of the end caps (back when they had metal tanks) and then pushing metal rods through the tubes to remove the crud, and then resoldering the tanks ends back together. This worked well on all brass/copper radiators, but these modern rads with aluminum core/plastic tank don’t allow this type of treatment, and replacement is the cure for plugged passages.

Some thoughts: If the heater core is plugged up, there is a good chance the radiator is in similar condition Use an infrared thermometer to check thermostat elbow temps against guage reported temps. Run a pressure test on the cooling system to make sure it will hold the required pressure (16lbs?). If it won’t hold pressure, boiling is likely to happen. Antifreeze raises boiling point as well as depressing freezing point. Be sure to run a proper mix, because a typical modern engine with plain water and a non-functioning pressure cap will almost certainly boil over.

If you have an engine with older (worn) bearings, a high volume pump “might” be beneficial over a standard pump. Regardless of pump type, I would recommend using one made my Melling.

Yeah, I have heard that some RENIX engines had a plain hex head bolt. Those are easier to remove since the clearance issues using a Torx or Allen socket are not a factor.

Just a big special hollow bolt must be removed to dismount the adapter from the block. They are also VERY TIGHT, typically. The head style changed over the years. Some were Torx, and some were Allen head. Don’t use the wrong socket type, or you will probably mess up the bolt and makes its removal doubly hard.

As someone who has deleted the load valve assembly, I will make an important comment about the current state of the brake tubing in the OP’s first photo: There is a LONG section of tubing that hangs out, unsupported, from where it is clipped to the “frame” rail until it joins the flexible hose the goes down to the axle housing. Leaving this tubing to flop around unsupported is inviting a fatigue failure cracking off the tube at some point. Ideally, some sort of bracket should be employed to attach the tube to the chassis right at the junction Of the flex hose and the tube. This is way the factory did it.

A timing chain is easy to pinpoint with a stethoscope, as that noise is very localized. A valve train noise rocker arm or lifter can also be narrowed down by stethoscope. A 4.0 can be run without a valve cover for short intervals at low engine speeds to also narrow down valve train noises.

My 4.0 was a transplant from a 2001XJ with the infamous “0331” head. Unfortunately, sometime in its past, one of the owners allowed it to overheat badly, popping the head gasket under the manifold side if the engine. And not knowing about the vulnerability of that generation of head casting, they just slapped a head gasket on it, fixed the overheating cause, and called it good. (They apparently didn’t know those heads can crack in a subtle way during an overheating episode.🙁) Not knowing it’s history, when I got the MJ, the engine still sounded good, and had clean oil….until I drove it about 1500 miles with the (unknown) crack in the head that allowed the oil to convert itself into a brown milkshake. 😳 After putting on a new head from Clearwater Cylinder Head, and replacing all the bearing shells and polishing the crank, I thought all was well. (The bearings really did not look too bad, but I wasn’t taking any chances.) 5000 miles later, I was getting this weird ticking sound that was VERY noticeable on a hot restart and stayed present to some degree whenever the engine was hot. Compression testing showed #6 cylinder was getting progressively lower as time went on over a period of 6 months. the problem wound up being a cracked piston skirt, probably caused during the severe overheating episode. I pulled the engine and sent it to a machine shop in Prescott, AZ, and had him put in a new cam, new oversized pistons, and polished the crank and put in new standard sized bearings. Then I had a small 6 month interruption while they replaced to valves in my heart due to a mysterious blood infection I contracted.🥴 After I recovered, I put the engine back in, and it’s as quiet and smooth as ever. I have about 2000 miles on it now, and am ready to switch to synthetic oil to deal with the high temperatures here in the PHX area.

OEM style tail lights are available on eBay from Key Parts. Aftermarket tail lights with integral LEDs that match OEM appearance are available from Oracle Lighting. I have these in my MJ, and they are brighter than the OEM style that have incandescent bulbs.

That’s more sophisticated than the damned Weber I had. Just a straight (plated) steel shaft thru an aluminum die cast carb housing.