AZJeff

The fact that the skldding issue returned after being gone immediately after installing new wheel cylinders makes me wonder if the drums were adjusted correctly once the new wheel cylinders were installed. In addition, are the self-adjusting mechanisms properly installed and functioning as expected? (A lot of guy crab about the self adjusters being a POS, but we old guys lived with those devices for decades, and learned to keep them clean. Also, the self adjuster only really works when the brakes are applied going BACKWARDS.)

Now that you have removed the faulting fuel injectors from the equation, the only other possible reasons for rough running would be something like a large vacuum leak or (more likely) something amiss in the ignition system. The ignition system should be pretty easy to diagnose. Here is what I would do: 1. pull all the spark plugs and examine for proper gap and no cracking of the insulator anywhere on the plug. Regap/replace as needed. 2. pull the distr. cap and inspect rotor and inside of cap for carbon tracking that will cause misfires. Replace as needed. 3. reinstall plug wires onto cap and do a "nighttime spark arc" test. This is done by placing the vehicle in a location where it is DARK (nighttime works well for this.) With the engine running, observe closely all the spark plug wires for any arcing between the wires and any grounds (or adjacent wires). The will be easy to see in a pitch black environment 4. A more definitive test than the nighttime spark arc test is to get a spark plug tester in the link below to observe spark when running for each cylinder. https://www.amazon.com/Ram-Pro-Engine-Ignition-Tester-Fool-Proof/dp/B01HU2L1NU/ref=asc_df_B01HU2L1NU?tag=bngsmtphsnus-20&linkCode=df0&hvadid=80882941400092&hvnetw=s&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4584482468120795&psc=1

Instantaneous loss of almost all power boost on the steering is usually traced to either low fluid, or an obstruction in the hydraulic lines. It is EXTREMELY rare to have the steering gear proper go from providing normal boost to no boost in very short order. Is the fluid CLEAN? Maybe you can start by trying to flush the system.

Virtually all the bolts that go into the engine block of the 2.5 or 4.0 are going to be SAE thread, because the engine was designed LONG before the push to metric hardware that started in the 1980's. That's a good little tip to remember when you start searching for wrenches or replacement bolts.

The sway bar proper supposed to have it's end (where the round hole for the sway bar link is located) positioned so it is parallel to the ground when the Jeep is at normal ride height. As one begins putting lift on the vehicle, and increases the ride height, it begins to pull the end of the sway bar downwards. The fix for that, of course, are extended sway bar links. HOWEVER....as the lift above normal ride height becomes more significant (and 4 inches is pretty significant), just adding longer links won't keep the sway bar from interfering with the spring. The fix for that is to reposition the sway bar mount where it attaches to the chassis further down and further FORWARD. Your Jeep has brackets that reposition the bar further down on the chassis, but they need to have an offset to reposition the bar mounting locations so the bar is moved forward slightly as well. One last thing you might want to check before you dive into relocating the sway bar on the chassis and/or putting on longer sway bar end links: Is your caster set up correctly, and is your wheelbase correct per factory specifications? I ask this because the photos show you having adjustable control arms on the vehicle, and all of that can be fiddled with to create the proper caster and wheelbase when they are installed. And likewise, if they are not adjusted properly when they are installed, they can create all sorts of incorrect dimensions an angles that can make getting the sway bar to line up and function correctly almost impossible. I say all of this because I went through your pain on my MJ a few years back trying to straighten out what a previous owner had done (or not done.)

The standard test for a vacuum operated brake booster to verify functionality is this: 1. with engine OFF, pump brake pedal repeatedly until the pedal feels solid 2. while HOLDING pedal down, start the engine. 3. as the engine begins to run and generate vacuum, the brake pedal should "sink" further with existing foot pressure If it does NOT do this, the booster is defective (assuming the hose from the booster to the manifold is connected and not cracked).

If the pulley on the compressor is moving, it is probably due to a worn out bearing in the compressor clutch hub. This can be confirmed by removing the belt, and turning the compressor pulley by hand. It should spring smoothly/freely, with no noise. If it is determined to be bad, a replacement bearing can be had from Rock Auto pretty reasonably.

That looks like one of those fancy Iridium or Platinum tipped plugs. The 4.0 doesn't benefit from them in the slightest, and may actually run worse, since they lack the extremely high voltages needed to jump that type of gap reliably. Put in some good old fashioned conventional plugs (Champions were OEM.)

No, it’s not supposed to touch. I don’t have the routing diagram so I can post it from my iPad, but someone can chime in with it, I am sure. if you do not have AC, do you have the AC delete pulley installed?

Who is your helper, there, Cruiser? And did she find the issue using that stethoscope?

It’s hard to tell from your photo, but I think I see cracks in the rubber. That would suggest a new balancer is in order

This is the best solution

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.