AZJeff

If you do NOT replace them, the condenser will flop around on it's top end. The will eventually lead to a condenser with cracks, and that will cause all the refrigerant to leak out. The rubber mounts are available new, so bite the bullet and get a new set.

So I have the 1990 FSM in digital format. How can we go about adding that to the downloads section mentioned above?

I agree that the yoke of the “C” looks splayed, with the upper branch of the “C” looks bent upwards. That might also imply the entire “C” is bent inward at the top. I will try to photograph one of my axle ends when I get home and post it.

A question for those who are reporting various electrical issues on MJ’s that usually start with a questions such as “what does this blue wire coming from the fuse box do?” ”what color wire powers my backup lights?” I have the electronic versions of the wiring diagrams for several of the MJ/XJ series, and find them invaluable for answering questions as this. I have had them for years, so I don’t remember where I got them. Are these available in a digital format from an non-copyrighted source that CC members can access?

Like almost all hydraulic valve lift equipped engines, the 4.0 does not have any way to adjust the valve lash. The lifters are supposed to accommodate that, assuming all valve train parts are of OEM spec. The only time you see any sort of adjustable valve lash system on a 4.0 is when people install aftermarket camshafts and rocker arms with other than standard lift ratios. One way to confirm if it's truly a valve train noise is to remove the valve cover and start the engine, and then try to use an automotive stethoscope to listen to each rocker arm at it's pivot fulcrum to pinpoint the noise. (Taking the cover off also lets you inspect the valve train for any abnormal stuff at the same time.)

All the steering linkage from a 2WD is the same as 4WD. Also, XJ linkage parts are interchangeable with MJ pieces.

BTW, the perimeter of the evaporator and heater core need to be surrounded with some sort of foam or similar material when they are installed into the heater box. If they are not surrounded, they will rattle around making noise, and air will leak around the heater core or evaporator, lessening their performance. Finding OEM foam is pretty close to impossible, so I recommend buying foam from a hardware supply place and cutting it to fit the spaces. the foam can be attached to the heater core or the evaporator with contact cement.

The fast-turn thread that goes in to the holes in the heater box is pretty easy to strip out when being reinstalled. If that happens, the best thing to do is to epoxy the screw into the stripped hole, and let it cure before trying to thread a nut on the other end. The nut is NOT attached with Loctite or anything similar. The integral washer on that nut is coated with a sealant on the surface that mates against the firewall. The sealant is designed to keep water from entering the cab through the mounting holes in the firewall. If the threads are coated in this stuff, they can be cleaned with a solvent (as can the nuts). A bit of clear RTV can be placed around the hole before the nut is tightened and that can provide the water sealing action that is needed. The thermostatic tube that is part of your older-style expansion valve should be placed in the center of the evaporator, between the fins. IT needs to sense the temperature of the evaporator in it's coldest area, so it can control refrigerant flow properly.

There are several reasons why Jeep stopped using CAD on the XJ/MJ, and reliability is just one of them, and is a big one. Unless you are restoring you MJ to factory original into every detail, keeping the CAD makes little sense.

Dirty Comanche is on to something here. The trend in designs has been AWAY from a mechanical parking brake being integrated into the caliper, and that's for a VERY good reason: the system is not durable. Corrosion and other environmental elements conspire to make the system less that totally reliable, and the cost to repair once it becomes jammed up with corrosion is costly. I know a lot of guys think a duplicate drum-type parking brake running in parallel with a disc-type service brake is a waste of hardware, but the benefits of it's reliability outweigh the added hardware costs.

In addition to the actual steering box mounting bolts, check for CRACKS in the "frame" where the box attaches. When guys add larger wheels/tires to an MJ/XJ, the strain put on the mounting location of the frame can increase substantially when the steering wheel is moved while the vehicle is stationary. This can lead to cracks in the boxed sheet metal structure that forms the "frame" in that part of the vehicle. You will probably need a flashlight and a helper to do a good inspection. Have someone turn the wheel just enough to apply a load to the steering box and steering linkage, and while he/she is doing that, look around for motion between the box and the "frame" (and any steering linkage parts as well, of course.)

I am a retired mechanical engineer, and I fully understand WHY the valve was put in. In fact, such valves were not uncommon on other brands/models at one time. However….auto manufacturers deleted that feature after they analyzed and determined that AC performance was not impacted significantly by letting the heater core receive a constant flow of engine coolant at all times. The driving reason for doing this, of course, was manufacturing part cost reduction and assembly simplification. It has been demonstrated by multiple XJ and MJ owners that deleting this valve does not seriously alter the performance of a properly functioning AC system. (it should be noted that deleting the valve does NOTHING to reduce heater performance whatsoever.) in other words, taking the valve out simplifies the heater hose routing, and has minimal, if any, noticeable effect on AC performance. That makes it a win-win for most owners.

I am surprised anyone is really suggesting replacing that stupid thing. The later XJ's eliminated this troublesome piece, and there were no adverse behaviors caused by that action. I would just ditch the valve, and replace the heater hoses with the more modern routing that the later XJ's employed, and never look back.

Radiator issues might cause overheating quickly, depending on environment, and for that reason might be #1. If oil pan shows signs of cracks, that's right up there as well. You are going to need taillights if you want to drive it on a public road, so that might be the next issue. The crossmember, as pathetic as it looks, is near the bottom. Thank God that XJ pieces fit here just fine, as there are a bazillion of those out there.

Cooling system maintenance is ESSENTIAL to a long-lived cooling system. And, given that the 4.0 MJ/XJ vehicles have a very marginal cooling system, it is doubly essential that the cooling system be flushed and refilled on a regular basis. Lots of people will be religious about changing oil, and then totally ignore the cooling system on the same vehicle. To do so on an MJ/XJ in particular is just asking for trouble.

Plastic tank radiators are the standard method of construction in modern cars (anything built after about 1995). For the most part, they are equivalent in durability to the older all-metal types. Like all other radiators, they are likely to fail due to corrosion because of lack of maintenance to the cooling system. if you flush your cooling system and replace the coolant periodically, you should see a reasonable service life from a rad with plastic/aluminum construction.

That's my buddy Robbie Layton. (Actually, I don't know him from Adam, but he is friends with Matt's Off-Road Recovery, and my son knows him.) Robbie is a REALLY GOOD body shop owner/operator. I wish I could afford to have him redo the paint on my MJ, but my wife feels that we need a house to live more than perfect paint on my Comanche.

I have NEVER seen any one use one of those down here in PHX, and in the 25 years I have lived here, I have had probably 10 windshields put in the various cars I have owned. The last 3-4 windshields that various shops have installed all involved using a very long handled "Stanley Knife" (aka utility knife).

I recently put a rad. in my 2014JK, and got it from Rock Auto. I chose a CSF with the OEM style plastic tanks and aluminum core. That radiator was made in Thailand, or at least that is what it said on the box. I have used CSF radiators in the past with no issue on my MJ and XJ. I think those were made in the Phillipines. We shall see how a made in Thailand radiator holds up. I was defect free out of the box. From my experience in sourcing parts in Asia before I retired, the Philippines and Thailand are several steps above China in quality and business ethics. (The Chinese will slip something over on a customer in a heartbeat if they think they can get away with it.)

I bought two inch thick foam sheet from Grainger, and then cut mine out with a large kitchen knife after tracing a pattern on to it with a black sharpie pen. I attached it to the heater box with contact cement. The edges are not as pretty as the die cut factory one, but it works just as well.

The proper term for that is the "cowl" of the vehicle.

Your average thief is not going to hang around your vehicle for long periods of time trying to figure out why the vehicle won't start. They want to smash a window, overpower the ignition lock, and be gone with the Jeep as quickly as possible. The longer they hang around a vehicle with a jacked up steering column and/or a broken window, the more attention it would attract. That said, I think HIDING the kill switch from plain sight does as much to defeat thieves as the actual kill switch itself. Putting an unmarked switch on the dash isn't nearly as effective as placing one in a location that a thief either cannot see, or would not think to look.

I have a center console in my MJ, and my kill switch is located inside the console, hidden inside the storage compartment in the console. Adding the siren/horn feature would require a method to detect unwanted attempts to start the vehicle, so that once starting is attempted while the pump is dead, it would trigger the horn. That's not a simple plug and play, since now you need an added sensor and circuit to indicate when the starter is engaged with the fuel pump power is off, and then trigger the horn in response. (It would also have to shut the horn OFF after you turn the fuel pump back on, for those times when you forget to turn the pump on before cranking. Ask me how I known. )

To some degree, that is true. Professionals (those who do windshields for a living) can get them out unbroken probably 90% of the time. Amateurs like myself wouldn't probably have NEAR that chance of success. For that reason, I never mess with windshields. I let the pros do it. Then again, I have full comprehensive insurance that covers my glass in my vehicles, so the cost to me is zero when I need a new windshield. (Side note: here in AZ, windshields have a surprising replacement rate. It it isn't flying rocks being kicked up by other vehicles, it's the pitting from wind-blown sand that trashes the visibility. I average a replacement glass on all of my Jeeps about once every 5 years. My JK Wrangler is the worst, where the nearly vertical surface insures that a rock hit will be a crack...on that vehicle, I average a new windshield every 3 years due to rock cracks)

To answer multiple comments on this thread: I have not tried the "5000" series Rancho shock, so I cannot comment on that particular version. I am just not a big fan of Rancho suspension parts in general, as I think there are better aftermarket brands than theirs, and at similar prices. The "Tab" various people are referring to on the lower end of the front shock absorber in an XJ/MJ is called a "bar pin"