AZJeff

About the hoses and the R134a versus R12: I wrote about this topic recently here, but the R134a molecules are SMALLER than those of R12. When R134a was introduced, they introduced a new type of hose with a “barrier” in the various layers that prevents the smaller molecules from migrating through the rubber. older hoses used with R12 lack this barrier, but there is a good side: old R12 hoses tend to be soaked in the R12 refrigerant oil. That makes them have an unintentional barrier to R134a molecules my accident. in other words, old used oil-soaked R12 hoses do fine with R134a in most cases. Most companies making new auto refrigerant hoses include the barrier regardless of the intended refrigerant, so replacement of old hoses is not an issue.

I think we are headed down a rabbit hole about the newest type of refrigerant. If the OP wants his AC to work, the smart (least costly/best results) would be to charge the system with R134a, and use the appropriate oil to accompany that charge. He can either do that himself (or with his buddies), assuming he can secure a charging manifold and a vacuum pump. Otherwise, the safe bet is to pay a pro to fill it with the correct type/amount of oil, and charge it with the appropriate amount of R134a.

Yeah, I forgot about that stuff. SInce I am a DIY guy, I have not encountered that refrigerant in the wild, thus far. My newest vehicle, a 2014 Wrangler, still uses R134a as it's OEM refrigerant.

Back to resurrecting this thread. So I put in a new NGK cam position sensor, and confirmed it's "timing" with the toothpick method per the FSM. No change. In fact, over the past month or so, it's actually gotten slightly worse. Now, if I leave the vehicle for more than 10-15 minutes, I have to crank the engine twice before it's starts. Once to get the control system to get a sync, and then the second time, it starts. It sure is acting like a loss of volatile memory is taking place. So, I am just spitballing ideas here: ---I checked the 12v "keep alive" power feed to the ECU, and it's working normally (at least up through the connector). However, I don't know if there might not be an internal issue with the ECU. Perhaps the feed is not getting into the actual circuit board inside the ECU. ---Or, maybe the capacitors in the ECU are getting old and bleeding down rather quickly with old age, and thus the ECU looses some memory settings due to capacitor drain. I seem to remember reading about someone who went in and replaced the caps in an ECU on some MJ or XJ, but I cannot remember which forum I was on where he reported doing this. I need some suggestions from our electronics wizards on this.

I have been following this conversation since it started, and I feel that I might be able to offer some suggestions, since I have done many AC repairs over the years to various vehicles, both older R12 ones and newer R134a types. 1. If you have an MJ that still is filled with R12, but needs AC work, that is the PERFECT time to do the conversion from R12 to R134a as a refrigerant. Some "purists" insist that, since R134a is not as efficient as R12 is as a refrigerant, any conversion will result in a less cooling system function. While that is technically true, the AC system in an MJ was designed for use in an XJ, which has more cabin volume and windows than the little cab the pickup has. This means the AC system in an MJ is already oversized for the job, so the slight loss in system cooling capacity won't be noticed. 2 Using substitute refrigerants like the OP's R12a is certainly viable, but, as others have noted, that stuff is flammable, which regular R12 and R134a are not. There is a reason that auto manufacturers don't use flammable refrigerants in passenger vehicles, and I think the reasons are obvious. I would stay away from them for the same reasons. 3. To do proper AC recharging, one needs a proper charging manifold/guages, and a vacuum pump. WIthout both of those, you CANNOT recharge the system properly or safely. If you don't have access to those tools, or have a friend who does, then your best bet is to do all the mechanical portions of the work replacing parts and adding refrigerant oil, and then take it to a professional, and ask them to evacuate the system and charge it appropriately.

I have used the setup that "knever3" suggested on my previous XJ's, and it's quite good. On my MJ, though, I went a different route for the actual headlight proper. I have some relatively no-name LED lamps I got off of Amazon. No Name LED Headlights They are not the longest-projecting lamps I have used, but they are a bright white, and the beam does not cause oncoming drivers to complain once aimed correctly. For REAL long range driving, I use an LED light bar I got from Quadratec that I mounted on the front bumper. Here in AZ, if you drive out in the boonies, you need all the light you can get, and that provides it. Also, the law enforcement community out here isn't terribly aggressive about vehicles having extra lighting as long as you use it sensibly (read that "not in traffic"), so adding more lighting is pretty common for rural applications.

The fact that the upper rad hose isn't getting hot is a sure sign that there is no water circulation. That COULD be the water pump, but more likely, it's a partially plugged radiator. The cooling system on the MJ/XJ is just barely adequate when all the parts are in as-new condition. Once any of them deteriorate, you can expect overheating pretty soon thereafter. One other tip: although you do not have a temperature guage, you can buy a laser infrared thermometer like this one on Amazon: Laser Thermometer It's pretty cheap, and can be very useful. Just point it at the thermostat elbow, and you will get a good reading on coolant temperature.

Yes, it’s the standard switch Assembly used in all older GM steering columns.

One other suggestion: Loctite makes a special kind of compound to retain sleeves on shafts. I would apply a layer of this to the area where you are going to have the sleeve positioned before you actually press the sleeve onto the shaft. Here is what you need: Loctite 640

You put the sleeve on the area where the seal will ride. The slip yoke normally only moves axially about 1/2 inch under normal conditions. (Rock crawling or other extreme axle flex would be greater motion of the yoke, but in normal road use, 1/2 inch is typical.) With your driveshaft installed and the vehicle at normal ride height, you should be able to find the spot where the seal rides. Center the sleeve over that spot.

The factory flares for the XJ are made from urethane, IIRC. Do some searching on how to bond urethane pieces together. There is probably a professional body shop product made for that task.

Since you are replumbing the system, I have found a butane torch with a pencil tip to be really helpful in loosening rusty connections. —Use a wire brush to remove loose corrosion —Apply hear to the flare nut with the torch —While good and hot, turn the flare nut with a flare nut wrench. Try to avoid using an open-end wrench, as they tend to round off the nuts. Only use Vise-Grips if the nut is too rounded off to get a wrench to engage the flats.

A lot of what you say there is dependent on ambient environment. Here in PHX,AZ, even a brand new 4.0 won’t run 30psi in the summer at warm idle. With 10w30 oil, it “might” make 25psi, and most of them will be closer 20psi. For that reason, I always recommend using the shop manual specs to judge engine oil pressure as to whether it is “good” or not.

IIRC, your MJ has aftermarket fender flares on it, and I assume you then have your front fenders trimmed to accommodate larger-than-OEM tires. if that is the case, you can do what I did. I bought 1/16” ABS plastic sheets on Amazon that were 12” by 24”. Two pieces would be needed to make each splash shield, which becomes part of the fender flare that extends inward into the wheel well. I cut and trimmed the 2 PCs to follow the shape of the inner part of the flare. Then I used a heat gun to form the curve of the fender opening. I the attached these pieces together in a butt joint with “pop” rivets. Then I attached the now curved flare extension to existing flare again using pop rivets. I overlapped the extension on the aftermarket flare by about one inch. The flares, once reinstalled, extend inward about 6-7 inches past the fender sheet metal edge, and this protects the entire area between the body structure and the inside of the fender. The result is much stronger/stiffer than an OEM splas shield. I can send pictures if you are curious.

Associated story —- My MJ was fitted with about a 4” lift by some previous owner, and it had that same secondary plate installed as the OP showed in his photo. All was well until I needed to replace the bushings on the springs and the shackles. NOBODY on the inter-web seemed to have the right diameter bushings, so I finally took the springs to a local shop, and asked them to replace the bushings. They told me that many aftermarket springs don’t use OEM sized bushings, and that’s why nothing I ordered would fir. They were able to match up some stuff and install it. I share this in case some other owner with other than OEM springs decides to do some repairs to his spring pack🤔

Good point. Any MJ getting down under ten mpg has some significant issues

I have 32" tires and a 3.5 inch lift. I get about 16mph in town, and about 18-19 on the highway if I keep it at 65mph or less. However, I also have the later 4.0 with the full OBD-II control system and the last head redesign. However, when I compare it to the older XJ's I had, they really didn't do THAT much worse--maybe 1pmg

Very good. I am glad your issue was relatively simple to fix.

Did you do the measurements I suggested? It would be ironic if the reamer wouldn’t solve the problem…..

Ugh. I have a new "distributor" I got through Rock Auto. It came with a cam sensor of unknown source. I would hate to buy a whole Mopar "distributor" just to get the cam sensor that attaches to the top. (The cam sensor used to be available as a separate part.)

Bueller?

Yes,there is some axial play in the ball stud, but I think the amount that is considered acceptable is probably MUCH smaller than what I see in your photo. The blue seal on the new ball joint MUST be in contact with the knuckle to function correctly. If you cannot ream the tapered hole in the knuckle to get the ball stud seated far enough to get the blue seal in contact, you risk dirt and contamination getting into the ball joint over time.

AND THIS is why we have Comanche Club. I had old XJ's and newer ones before I got my MJ, and I had NO IDEA that they changed the ball joint taper at one time. What's up with that, BTW? I still don't think it's a bad idea to check the yoke on the axle, just in case. My axle was trashed by some former owner using other than the appropriate tools, and one side of the "C" for the yoke was splayed a good 7mm. There was no easy way to fix that. Thus, I wound up with a low pinion from axle from a 2000XJ as a replacement.

I hate to say this, but the most likely cause is the “C” shaped yoke on the end of the axle is splayed. This happens when someone in the past did not use the proper adapters to remove/install a ball joint. you can confirm this by measuring from the outside of the yoke on each side to see if they are equal (within 1/16”)

I guess the secret to my suggesting solder is that I am a BIG fan of wiring looming (the corrugated type stuff) and Tie-Wraps (nylon wire ties). My wiring tends to be pretty secure, and because of that, I have never had a solder joing crack due to vibration.