AZJeff

For checking steering linkages, I like to get a helper to sit behind the steering wheel and move the wheel back and forth just enough to get the front road wheels to begin turning right or left SLIGHTLY. (Do it with the engine off.) While he/she is wiggling the wheel, lay under the vehicle an place your hand around each steering linkage joint. You are attempting to feel for relative motion between the two parts of each joint. There should be none. If there is, that joint is bad. Next, jack up each front wheel and place a large pry bar under the tire. Lever up on the pry bar, and look for any motion between the wheel assembly and the axle housing where they are connected by the ball joints. Any motion means one of both ball joints are bad. Control arms are best examined with a strong flashlight. You are looking to see of the outer sleeve of the control arm bushing is still centered on the inner pivot/attaching bolt. Looks for cracks in the rubber that fills the space between the outer sleeve and the pivot bolt. if there are significant cracks, or if the bolt is eccentric to the outer bushing sleeve, the bushing needs replacing.

Let me ask a question--have you actually seen symptoms of overheating (radiator boil-off)? Have you confirmed that tne temperature is as indicated on the instrument cluster? I ask this because in my MJ (which has a late model XJ dash), the gauge reads about 10* higher than the actual temperature of the coolant. I use an infra-red laser thermometer aimed at the thermostat housing to verify what my guage says, and perhaps your guage (or sender) are not giving you real temperature readings.

It's possible that your flexible rubber brake line between the chassis and the rear axle has collapsed internally and is blocking fluid flow. I would start by disconnecting the chassis end of that line and see if fluid flows. If it does, then reconnect and check the axle end of the line in the same manner. In all honesty, with vehicles as hold as ours, unless the flexible brake hoses are new or appear to be recent, replacing them is a wise safety precaution.

I think that "check valve" is an overpressure safety valve. I am not familiar with all the fittings on the older MJ's, but that is what they looked like on my old Ford F150. I am certain that others can confirm if that is what this part is on your MJ.

In general, I am not a big fan of closed cooling systems, (although the wife's KJ has one, and it seems to work fine.) If I was replacing the coolant tank more than once in a few years, I would be HIGHLY motivated to convert to an open system, as they don't seem to be as vulnerable to crappy aftermarket parts as do the closed systems.

Was there any reason you didn't lay into it with a propane torch? If the expansion valve was aready off the vehicle, the amount of refrigerant was pretty much zero, so heat would not generate noxious gases, but it sure would loosen that rust.

Cruiser, where do you dig up this stuff? I am impressed. And for the OP, aside from the fastener size difference on the four "corners" of the pan, I just put the ones with the stud heads on them whereever I see a bracket that is supposed to be anchored to the stud side. That's usually the trans. cooling lines, and the O2 sensor wires on the model years where that is applicable.

When temperature drops dramatically when the vehicle starts to move, it's because air is now flowing over the radiator at a much higher rate than when the vehicle was stationary. The cooling fan(s) are supposed to cause air to flow when the vehicle is stationary. If they do NOT, then coolant temperature will rise dramatically. All MJ's have one mechanical cooling fan with a viscous clutch. Most MJ's also have an electric fan that acts as a booster, and is present if the vehicle has AC or a heavy duty cooling system. We will ignore this for purposes of this discussion. When this mehcanical clutch/fan (and associated fan shroud) are properly functioning, the fan should be able to keep the engine within normal operating range when the engine is idling and stationary. It sounds like your clutch is not engaging properly, and allowing the fan to "slip" on it's shaft even when the temperature would call for the clutch to "lock up" and allow the fan to spin at high speed. In addition, when an MJ is running down the road at a speed of 45mph or more, the fan no longer becomes a factor in keeping the engine cool. There is enough air entering the radiator through the grille to keep the temperature at the normal level, whcih should be about 210*, give or take 5-10 degrees. If your temperature is dropping to much lower than 210, it means your thermostat is opening WAY too far, and allowing too much coolant flow through the radiator, and thus OVERCOOLING the engine. A new, high quality/brand name thermostat should fix this. Be sure to get a thermostat set for 195*, and NOT one that is set to open at lower values like 160* or 180*

So far, my search using the recommended "car-part.com" shows the nearest short block that is suitable for build to be over in TEXAS There are places closer that have a complete engine, but they are all suitable to drop in as is for a replacement, and they are $1000+ I certainly don't need a working engine to use as a basis for a rebuild of a short block, so I am really frustrated. Given how ubiquitous the 4.0 was for so many years, I am having a REAL hard time believing there are not worn out engines in junkyards somewhere here in AZ.

So I found out my neighbor is buddies with a guy who has a race car machine shop, and might be able to do trustworthy work. Now I am trying to find a rebuildable short block. The search engines I found are TERRIBLE at showing what sort of inventory various junk yards have. Does anyone have a recommendation for a good searchable database for a auto salvage yards?

That's 52 miles from where I live in Queen Creek. I am going to see what Stamps Automotive can do in Gilbert. That's about 10 miles away

My biggest issue is finding a suitable machine shop that isn't 50+ miles away. They seem to be really few and far between here in the part of the Phoenix metro area in which I reside. I DO like the idea of being in control of what goes into the block during rebuild, though.

So after I changed the head on my engine (due to the famous "0331" head crack issue on my 2000 XJ engine), my engine has shown piston slap issues. And my oil analysis reports from Blackstone Oil Labs confirm that, in spite of my decent oil pressure and decent compression, shows an abnormal amount of aluminum in the oil. I think one or more pistons are cocking in the bores and making racket. (it's noticeable on hot restarts, or during the warm up period.) My original plan was to build a stroker, but finding a decent crank and rods from a 258 is proving challenging, to say the least. So "plan B' is to pursue getting a reman. short block for a 2000 4.0L. (I have a NEW cylinder head from Clearwater, along with all new valve train, except the cam, on the engine, so I don't need a total reman. engine.) I saw where "MABBCO Motors" out of Texas offers reman'd short blocks. My question is...are they any good? Can anyone recommend any OTHER sources for a competently built reman.?

Of course, that requires the lower control arm links to be cut off the Libby axle, and leaf spring perches to be welded on. If you have welding skills, or know someone who does, that is an excellent suggestion

If you think the backing plates are corroded to hell, I would sacrifice them and start by using and angle grinder with a cut-off wheel and chop the outside of the area drum where the shoe rides in about 6-8 places around the drum. This cutting will go thru the drum outer wall, and through part of the backing plate, and probably through part of the shoe face. Then squirt in some of the best penetrating oil you can find. Acetone mixed 50/50 with ATF is very good for this. Flood each of the saw cuts as best as you can and let it sit a while. if that STILL doesn’t get the drum to move/rotate, then start cutting on the front face of the drum between the previous saw cuts you made. DO NOT cut far enough inboard so as to harm the axle flange itself. Once the cuts are made, you can now pry off the drum segments to leave just the part of the drum that contacts the axle flange. and start to apply penetrating oil to the joint between the drum hub and the axle flange. At that point, heat, and a chisel between the drum and axle, along with a big hammer should get the rest of the drum off. Then it’s just a matter of removing all the remaining trashed parts.

The variable ratio function is accomplished by having the worm gear (on the shaft connected to the steering wheel) having a varying "thread" pitch. The further away from the center of the thread, the faster the thread pitch becomes.

That is exactly what the track bar is….a pan hard rod by another name!

I gotta ask one question, OP: you are here in the PHX area, and it's already been warm enough to use the A/C in a car. Does your MJ have A/C? I mention this because, although my MJ has the OBD-II control system and instake manifold, and thus is not exactly like yours, my idle will jump up and down slightly depending upon whether the A/C compressor is on or not.

I was never a big fan of the chassis end of the track bar being a sort of tie rod end device. For that reason, I ditch the OEM style track bar and it associated bracket for something that uses a traditional bushing/bolt on the chassis end, even if the vehicle isn’t lifted above factory ride height.

I vote with Cruiser's advice. I am a big fan of "do it once, and do it right", but I don't see the need to "refresh" a head with those compression numbers.

Aside from the nicks in the crank, those striations are going to make the seals job just about impossible using an OEM rubber lip seal. I really don’t understand why they are present if the engine used the normal two-piece rubber Kip-type seal😵‍💫

So did AMC ever use a rope seal on their six cylinder family from which the 4.0 is derived? (Is this crank possibly out of one of those older engines?)

Chances are the aluminum bracket has oxidized around the threads and created a mechanical bond. Drilling, in stages to increase the hole size in the bolt will thin the walls of the now tubular bolt. Then plenty of heat on the aluminum, will cause the bracket to expand and make the bolt easier to turn. Lay a propane torch on that bracket for about five minutes, and that oxide will break down as tha aluminum expands away from the steel bolt.

I am not sure, Pete. That crank has a number of defects in the sealing area, and the photo only shows 1/2 of the total circumference. The other side might be worse! Also, those striations (diagonal lines) on the sealing surface are something I have only seen on shafts that typically also have an oil slinger. It’s not something I have ever seen on a crankshaft before. How did the striations get there? Is a special seal employed with that sort of surface? (I am trying to remember if any of the cranks that used those “rope type” seals had those striations…..)🤔

The lip faces INWARD towards the engine. In other words, the edge of the lip that rides on the crank should be AWAY from the flywheel/flexplate. I assume that you have inspected the crank for nicks or gouges in the area where the seal rides. Any damage to the crank will make the seal ineffective.