AZJeff

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.

If the OP is in the Atlanta area as his sig line says, a quick internet search will show plenty of shops that cater to the auto body repair industry that sell custom paint and similar supplies in the metro area.

If you have erratic idle, I assume the throttle plate shaft is loose in the bores of the throttle body housing. This causes the throttle plates to have varying degrees of clearance around the Venturi each time the throttle plates ope/close. I had this happen on Weber carb on a 2.0L Ford engine back in the 1970’s. There are only two ways to fix this: get a new throttle body assy or get a machine ship to bore out and install brass bushings into the wallowed out holes in the existing throttle body. neither way is terribly cheap, unfortunately 🥴

The fix there is a new (used, good condition) wiper arm shaft assy. from a junkyard

If the bushings are new, then the only other possible source of slop is the arm shaft itself being loose inside its body mount. On an 87 vehicle, that quite feasible.

Yup. Although it’s not a critical measurement, as long as it’s above MIN and below MAX

Why not just make a hard line from some pieces of copper plumbing soldered together, and the use regular pieces of heater hose and clamps to join it to the existing fittings? that’s what I did with my wife’s Liberty

I have broken several fan shrouds on the 4.0 mechanical fan over the years, trying to wrestle them out with the fan still bolted to its pulley. Then I got smart: I studied where the shroud interferes with the viscous clutch hub and used a Dremel tool to grind a clearance cut in the lower parts of the shroud, and sanded the corners of the cut to prevent cracking from sharp corners. Now I can remove the shroud by taking out the two top bolts and carefully working the shroud up around the blades and past the clutch. It’s a snug fit, as I wanted to keep the shroud as functional as possible, but I have not broken one since I did this mod. (Something Jeep should have done to begin with🙄)

That sounds about right, but to be honest, I never torque “non-critical” fasteners like that. I use my “calibrated wrist” acquired from 50+ years of wrenching on stuff. The t’stat bolts need to tight enough to keep the parts sealed, and to keep the bolts from loosening. Beyond that, there are no critical factors. Stuff like head bolts is another issue, so because the gasket must be compressed a certain amount to achieve a seal against the pressures and temperature of combustion. Likewise, lug nuts must be tight enough to create sufficient friction between the wheel surface and the brake rotor (or drum). THOSE types of fasteners I always torque.

RTV gasket sealer can compensate for “some” roughness on the gasket mating surfaces, but if the T’stat housing is really pitted, I would just get a new one. in fact, in my experience, I have yet to see a t’stat that is over 10 years of age that does wind up having some nasty corroded surfaces on either the gasket areas or the neck where the hoses clamp. That usually drives me to replace them under those conditions.

If you can remove the gasket from the surface of the t’stat housing or the head, it might be able to be reused. However, it would be best to use a new one, given the fact they only cost a couple of bucks. I assume you used a sharp/smooth scraper to clean the gasket surface on the head to insure it is free of all old gasket and other crap. If necessary, use some emery cloth to make it nice and clean. The cast iron head won’t be hurt by hand sanding with 120 grit cloth. The thermostat housin, being aluminum, must be treated more carefully. I don’t recommend using any scrapers or other aggressive tools to clean that surface. A wire brush, or better yet, a wire wheel on a drill, will clean the surface quite nicely. When I do a t’stat, I coat both sides of the gasket with the appropriate RTV and then assemble it all together and wait a few hours for the RTV to set up before I fill the engine with coolant. I know some guys recommend to never use gasket sealer in conjunction with a conventional gasket, but a t’stat gasket is one place where I think it helps and does no harm. One other tip I learned the hard way doing the thermostat on my dads 1968 Ford when I was 17 years old: be sure that the flange on the actual thermostat sits into the counterbore in the cylinder head. If you don’t, then the gasket can’t seal properly, and when you tighten down the bolts, you can crack the housing flange by the bolt holes😡

You should not have to dismount the compressor to R&R the water pump.

That is exactly how I do it. I have a long thin screwdriver (about the same diameter as the studs on the fan) that I place between two of the nuts to hold the pulley from turning. Then I put a wrench to another one of the four nuts. Do this working your way around the pulley.

Interesting. Those are different than the ones from my old XJ and my current MJ with a 2001 XJ head.