AZJeff

The reverse flow water pump would actually make the problem worse the faster the engine ran. Engine blockages would have to be caused by some REALLY cruddy coolant, and/or the use of some of that stupid stop-leak crap prior to you flushing it, but you say the coolant looked OK. In other words, anything that blocked the smaller passages in the block would have completely obstructed the heater core, and you did not report you saw any issues when you flushed it. Here in Phoenix, my cooling challenges should be as bad, or worse, than yours in Texas. I run a 3-row all metal radiator in the MJ/XJ 4.0 engines because of that, and other than my guage being somewhat off, my cooling system works as designed. As far as engine temps, what are you using to measure them? The gauges on the instrument panel are not terrribly accurate (mine is off by about 15 degrees). I always confirm temps by using an infrared thermometer and measure the thermostat housing. At this point, I am suggesting you confirm temps before tearing your hair out.

Cruiser, do you have any local folks you would trust? I ask because the nearest shops to me are in the downtown Phoenix area, which is 50+ miles from my home. If I am going to fight city traffic to get a head, I want it to be a good one. With Clearwater, I know they have a good reputation. But, if you know of someone here in AZ, I am open to ideas.

Guys...I KNOW I have a "0331" head, and I KNOW it has a crack. I have cleaned and inspected it. It's got the signature crack in the "correct" spot. So I KNOW I need a new head, and I WANT the "TUPY" type. Clearwater has those, I think. Is that the best choice, or is someone else offer something better/cheaper/closer?

So my MJ has suffered the dreaded “0331” head crack syndrome common to the late XJ 4.0 engines, and I need a new head. Is Clearwater Cylinder Head still a “go-to” place for a replacement head?

Some of the major highways here in AZ have 6 percent grades that run for MILES, punctuated by short flat sections in the middle. There is no way you can keep enough momentum up to climb that grade without downshifting.

The OP talks about having trouble maintaining speed on ground that is not flat and level. Those of us here in AZ often encounter long mountain grades on the highways, and those are a challenge for high speed driving. For example, my MJ has 3.55 gears and 31 inch tires. It's also an automatic, but it cannot hold 65mph on long uphill grades and stay in overdrive. It keeps wanting to kick down. My solution is to drop it out of OD when climbing grades. My XJ with 3:07's did the same thing, so I wonder if the OP is expecting too much from that driveline arrangement. Also, don't forget that, when climing moutain grades, you altitude is going up, and that means your air density is going down, so the engine is starving for oxygen to some degree.

PRO TIP: Don’t let foreign material fall into the intake manifold and then fail to retrieve it before starting the engine. While installing the new intake manifold gasket on the MJ the other day, I decided it would be a good idea to keep stuff from falling into the hole where the throttle body mounts, and so crammed a hunk of old tee-shirt as a “plug” in this hole, and it worked just fine. When I installed the throttle body, I pulled the tee-shirt plug out and bolted up the remaining intake parts. Now came time to start it up. It starts right away, and runs smoothly immediately. I let it warm up, and check for fuel rail leaks, and all seems good to go. Now for a short test drive. I pull out of the garage, and about 400 yards down the street, the engine starts running rough. REAL rough. I nurse the machine home, and shut it off. I look under the hood, and see nothing amiss. No loose hoses, no disconnected wires. I start it back up, and I hear a VERY noticeable whistle coming (like a MAJOR intake manifold vacuum leak), and it seems to be coming from around the area of the throttle body. I pull the throttle body and begin inspection. The gasket on the bottom looks fine, but then I peer into the intake manifold, and see a small amount of cotton rag material off to one side of the opening. That’s odd…. I grab the rag piece, and start pulling. Out comes a HUGE hunk of tee-shirt, about 15 inches long, and about 4 inches wide. Judging by the burns on the one end, it apparently ran all the way down one of the runners of the manifold, and was probably getting beat up and burned by the intake valve. After I removed the piece, I spent a while fishing in the manifold for any other pieces, but nothing came out. I reassembled it all, and started it up. It ran pretty crappy for a few minutes, and then the engine smoothed out. My theory is that the hunk of tee-shirt rag I stuffed into the throttle body hole was actually TWO rags, and when I pulled out the first one, the second one fell down into the manifold and I failed to see it. When the engine was idling, the rag stayed put. Once I started moving down the street, the airflow in the manifold sucked the rag into the intake port for cylinder #2, and it began to choke on that cylinder, creating the rough running. Now before any of you declare me unfit to work on anything more complicated than a door knob, please know that I have been working on cars for almost 55 years. I had done LOTS of intake manifolds, so this wasn’t a venture into uncharted territory. It WAS, however, the first time I ever left a rag in an intake runner!! In the end, it’s pretty funny. Had my error been made on a more modern engine with limited (or no) valve clearance, I would have been tearing the engine apart after that mistake. Thank God the AMC six is too primitive to have problems dealing with a few bits of cotton rag.

Heads up to those who offered suggestions: I put some adjustable arms on my MJ, and set the length and caster to match the recommendations for a 3.5-4" lift. My spring interference issue is gone, and the truck rides quietly. (Or at least as quietly as an MJ can ride.) Thanks to all who commented.

I can start your collection of components. I have a set of fixed length control arms that are good for a 4” lift that I will give you. All you have to do is pay shipping costs. The bushings on the arms are OEM rubber, and either are new or like new

That variation in inlet shape will not have any impact on cooling. The flow rate isn’t high enough to be affected by the variance.

Unless the black part is chalky, just mask it and paint the tan part. Otherwise, mask the tan and also paint the black part satin black.

How is your door weatherstrip? Does it still compress when the door is latched, or is it permanently collapsed with old age?

BTW-those are not “rivets” holding the vent assembly to the tan trim panel. Those are “heat staking” joints where the one plastic piece is melted over the other to form the equivalent of a riveted/welded joint. Careful use of a Dremel tool can separate the pieces, but a suitable adhesive just then be used to reattach them. because of this, masking the one piece while painting the other is best for this type of situation. i say this because, when I worked for a living, we used heat staked parts all the time in plastic assemblies.

This is the place!! THANKS.

The following website can tell you what gear you need: http://gojeep.willyshotrod.com/HowtoSpeedoGears.htm You might try all the usual sources for the speedo gear. I got mine from Quadratec, but that isn't the only place nor always the cheapest. The silly gear is really expensive considering what it is (a big custom plastic molded gear), and generally will set you back $25+ new.

There was a thread I saw recently where someone was offering decals that mimic the style used on the later XJ's on the front doors. These graphics would say "Cherokee", of course, on an XJ, but this person had created a version that used a similar font/size that said "Comanche" Does anyone remember where these were being offered for sale?

Yeah, I think I am going to go that route. It will get me the correct lengths, and a bit more caster, which, as you say, is a good thing in my book as well. Thanks.

Your problem is an easy one to fix. The link mentioned above (and reposted below) will do the trick, but you might need to fab your own relocating brackets. I have already done this on my MJ:

I already took out the springs, and inspected them when I replaced the coil isolators where the top of the spring seats on the chassis, so I know the springs are fine. (Other than the fact that they are bowed slightly forward when installed, resulting in the close proximity to the track bar bracket.) I am positive that the XJ/MJ, as designed, had more than 1/4 inch of the clearance between the outside diameter of the coil and the track bar bracket, and that the bowing of the springs is not normal. I am leaning towards one of two explanations for why the coil spring is bowed/arced forward: 1. crappy Rusty's springs that are not straight. 2. forward can't to the lower spring seat, causing the spring to be tilted forward on it's bottom end. (The upper and lower seats are, in essence, not parallel at normal ride height.) Since the spring is NOT bowed when I remove it from the vehicle (it rolls on the concrete floor quite nicely), I am discounting explanation #1 above, and am tending to think #2 is my issue. I am thinking the canted spring seat is being caused by the axle being tilted forward beyond the recommended/designed angle. Since my UCA's are longer than recommended for a 4 inch lift (but my LCA's are at the recommended length), the longer UCA's are pushing the top of the axle forward and causing the axle tilt. I am inclined to buy new UCA's, but want to make sure that investing in some good aftermarket ones will actually fix the issue, so I am seeking experienced inputs here.

I have been chasing a "sproinging" sound in my front suspension for a while, and did a whole bunch of upgrades/repairs trying to eliminate it. These included: 1. new control arm bushings (and they bolts are torqued to spec., and maybe then some) 2. new spring isolators 3. new bump stops (jounce bumpers) 4. new track bar ball joint end 5. new shocks All of this has been to no avail, (not that those parts didn't probably need to be made better anyhow.) But my issue remains. When I go over a curb (or other similar road bump), I get a "sproing" type of sound from the left front wheel area. I did some searching around under the front end, and I noticed two odd things: 1. the front springs are curved/arched slightly forward when the vehicle is at normal ride height. (These are "Rusty's" brand springs with a nominal 4 inch lift, but I cut about 3/4 of a coil off to achieve a slightly "nose down" attitude on the truck when unloaded.) 2. the clearance between the coils and the OEM style track bar bracket is really pretty small, at about 1/4 inch. I attached a picture that shows the clearance. I repainted the two parts, and took it for a test drive over some curbs in the neighborhood, and when I got back, I could see there is some paint rubbed off both the spring and the bracket. This is not my first rodeo with the XJ/MJ, so I checked by control arm lengths. The lift was on the Jeep when I got it, so I wasn't sure what to expect. I found the UCA has a length of 15.8 inches, and the LCA's are 16.2 inches. From what I know about recommended lengths for a 3.5-4 inch lift, this makes the UCA's too long by about 0.8 inches. I know that changing to a shorter UCA could cause the lower spring seat to rotate rearwards, and that would decrease the forward arch of the spring. But would it remove the close fit between the spring and the track bar bracket? Input from knowledgable XJ/MJ suspension wizards is appreciated here. If I am going to buy new parts, I want them to fix the issue once and for all. Clearance.pdf

That is not automatically a requirement when converting an R12 system to R134a. While the newer hoses do have a barrier membrane in them to prevent leaking of the smaller R134 molecules, it’s well known that old R12 hoses that have been saturated with R12 type refrigerant oil are pretty sealed from R134a leakage. On a 25+ yr old vehicle that had working AC most of its life, the oil saturation potential is pretty high. Otherwise, the comments from “Minuit” are pretty much spot on.

The least “scary” method is to use the FSM approach. Disconnect the track bar and drag link and sway bar links. Then support the chassis on tall jack stands. Place floor jack under axle, and disconnect the lower shock mounts. Then loosen all control arm pivot bolts and lower axle as needed to remove spring tension. Depending on spring free height, and control arm length, the upper arms may need to be disconnected from the axle end. I have done what you are proposing with spring compressors, and its much less anxiety-inducing to do it the way I described above.

That is correct. Heim joints do NOT have any sort of seal to keep out moisture or grit. Because of this, they wear out VERY fast in regular road use.

How practical/easy is it to create drastically different caster angles between the 2 sides of the front axle?

My 1992 XJ had the "skinny" type turn signal/CC control stalk, for what it's worth. I remember because the switch died in it, and I had to order and install a new one back in about 2001.