AZJeff

How about trying an induction bolt heater to loosen the rust?

I agree, but I would reverse the order of steps: 1. pull diff cover, and inspect fluid for signs of significant metallic content. If found, get someone who knows differentials to remove/inspect/repair source of metallic content. 2. if no metallic content found, replace pinion seal, and retorque pinion nut (with Loctite on threads) to 250+ ft. lbs.

AGREED. I HIGHLY recommend that you use what is called a "flare nut wrench" on those fittings if they are the least bit rusty. Also, some heat from a propane torch will help loosen the rust as well. Some people get all worked up about using heat near a brake line, since brake fluid is theoretically combustible, but I have never had any issues. Then again, I am not applying heat to such a degree as to cause things to get cherry red or melt, either.

You know, I might stilll take you up on that. Let’s take this back channel and plan a meet-up.

I just perused the Steelerubber catalog, and I am pretty sure they have a gasket that will meet my needs. They sell it by the foot, so I can buy as much as I need to get the fit correct. THANKS FOR THE TIP ABOUT THESE GUYS!!!

I have checked ALL of those sources. A few sources point to Mopar OEM, but when you look at the details, it says "no longer available". I look at eBay, but I do not want weatherstrip from around here in AZ, because the heat/sunlight makes rubber parts dry out and crack. Oddly enough, no wrecking yards on eBay seem to be listing this item.

The wife's 2004 Jeep Liberty has door gaskets that are finally giving out. I have been searching for a source for a replacement, but so far, and found nobody that carries weatherstripping that is intended to be OEM replacement equivalent. Of course, Mopar says the part is discontinued and no longer available. Can any serious Jeep experts one offer a suggestion for a source?

That was a brilliant thought, Cruiser. I figured it would be easy to spot the cylinder(s) with bad slap by turning off the added pressure of combustion of fuel. With combustion not going on in that cylinder, the slap sound would be diminished. So I started the engine, and let it warm up into the "most noise" phase (about 5-10 minutes after startup.) I then went down the line, pulling one injector connector at a time. (Am I ever glad i replaced all the injector connectors 2 years ago, so they were easy to snap on and off.) Guess what? Other than running rough when each individual cylinder was deactivated, the sound did NOT CHANGE when any given cylinder was shut down. So now I am mystified. The sound never changed when any cylinder was diactivated. So I wonder what is the source of the noise. (I have not checked bell housing to block bolts yet, BTW.)

So I did two things after the previous post: 1. I did another compression test. Below is a comparison of numbers after the installation of the new cylinder head (old psi), and now after 5000 miles (new psi) on the new cylinder head. Cyl. Old PSI New PSI 1 144 140 2 150 140 3 152 149 4 155 146 5 151 144 6 157 138 Then I also used my super-high-quality Chinese borescope to look inside cylinders #1 and #6, to see what it looks like. The attached PDF gives you an idea of what I saw. So I am getting frustrated with the cold start "ticking" I am hearing. If I KNEW that it was not harmful, I could/would ignore it, but I am fearful of some calamity down the road. Keep in mind that this MJ is not a beater vehicle. It's pretty primo, and could/would command a premium price on the market if it was for sale (which it is NOT.) A noise the inhibits its durability is something I want to address. 270384662_BorescopeImages.pdf

I measured the lift on the cam with a dial indicator when I was determining what engine damage may have happened with the cracked head. All lobes measured within spec. (I had the dial indicator on the pushrod side of the rocker arm.) I ran the engine at 2000RPM for 20 mins after I put in all the new lifters. I am going to try something else. I have a borescope, and I am going to try to poke it down into the spark plug holes and look at the cylinder walls on the back couple of cylinders when the pistons are at BDC, and see if there is major scoring from the piston skirts rubbing.

The flex plate bolts were tight. That was one of the first things I checked. There are no metal chunks in the pan. I have had it off twice and never saw anything in the pan. The oil analysis from Blackstone Labs shows no abnormal amounts of aluminum, iron, or copper. I run Rotella, with ZDDP, and a Wix filter. If anything is broken/cracked, it has not made it into the pan, nor has it showed up as particles in the oil. I will check the bell housing to engine bolts as suggested.

The first thing I did was to whip out my stethoscope, and I found the noise is coming from the rear of the engine. It's not up high, and it's not really down at the bottom either. (Using the scope on the side with the manifolds is pretty much impossible, so I did my listening on the camshaft side.) It's most noticeable a couple of inches above the joint between the block and the oil pan. I pulled the valve cover recently, and actually ran the engine with the cover off. The noise is definitely not in the valve train. I run Rotella with some ZDDP additive, and my last oil analysis by Blackstone Labs said there was no unusual levels of metal in the oil.

My MJ has a HO engine from a 2000XJ in it. About 5K miles ago, I discovered I had a crack in the famous "0331" cylinder head from this vintage of engine that was causing coolant to get into the oil. I discovered this when changing the oil, and I noticed it was not the pure black that old oil exhibits. It was more gray, and its viscosity was "funny". At the time of this discovery, the engine was making no weird noises, nor showing oil pressure or temperature issues. I was fortunate in that I found it before it destroyed the entire engine, so I did the following: --New cylinder head from Clearwater Cylinder Head in FLA. Also included new valves and springs. --New lifters, rocker arms, and pushrods (old ones looked fine, but I was going full bore) --New crankshaft bearings for both rods and mains (Clearances with old bearings were within spec., but I wasn't taking any chances.) --New timing chain and sprockets (I was in far enough that this was cheap) --New high flow Melling oil pump With all of this done, the engine runs well, and generates acceptable oil pressures per factory specifications. In addition, compression numbers are pretty close to fantastic, running (literally) between 135-140 on all six cylinders) HOWEVER....I have a noise that has been around pretty much ever since all this work was done. It has not gotten worse during this time, and professional laboratory oil analysis does not show any unusual metallic levels indicating high wear. I cannot seem to capture a good clean audio of the sound, so this is a good video of a very similar sound to mine (but mine is not a loud as this.) Piston Slap Sound Here are the symptoms: 1. The sound is non-existent upon startup, and reaches its most noticeable level when the engine has been operating for anywhere between 5 and 20 minutes. After that time span, the noise diminishes to almost imperceptible. 2. It is worse in cold weather. In ambient temperatures below 60 degrees, the amount of noise is a bit more, as is the duration of the “noisy time period”. 3. It also will make the noise on a restart of a warm engine if it has sat for more than 5-10 minutes, but the noise will disappear within 5 minutes after warming up on the restart. I have checked the flywheel for cracks and/or loose bolts, with no issues seen. This leads me to believe it's piston slap, in spite of the fact that when i pulled the head, the cylinders looked just fine. So here are my choices to fix the issue: ignore it, as the engine can last 10’s of thousands of miles with the sound, assuming it is piston slap. This is what Hagerty suggests, based on my internet searches. pull the engine and do a total rebuild of the short block. I have an almost brand new head on it, so I don't need that part redone, but the machine shop work would be some serious coin. do a cylinder rebuild in the chassis. Pull existing pistons, hone cylinders, install new pistons and rings. This, of course assumes that the cylinders don't look terrible when I pull the head, but I think they are OK, because when I installed the new head 4k miles ago, they looked good. This approach is cheaper the #2 above, but has it's own risks, of course. So for this guys who are deep into engine sounds, causes, and cures, what say you?

What does the fluid look like? Is it dark brown, or does it have some reddish coloration still? If it's dark brown, and fluid change (or two) might help the situation. The first change should probably entail taking down the pan, and looking to see what kind of crud is on the bottom of the pan and the magnets on the inside surface. Trans fluid is supposed to be highly detergent, and should keep non-metallic crud in suspension for the most part. A healthy transmission should only have a very light film of stuff on the bottom surface of the pan. This is mostly composed of clutch material that settles out. If the pan is coated to the point that you cannot see the silver surface of the pan bottom, that's concerning. Metallic stuff (of which there should be VERY little on a healthy transmission) should stick to the magnets in the pan. It normal to have a fine coating of "paste" covering the magnets, but no chunks and no bright slivers. Since the pan only drains about 3.5 quarts at a time, you might have to drain, refill and run it and then repeat the processs several times to get as much new clean fluid as you can into the machine.

With that crack in the head, there is NO WAY that gasket is going to last for any length of time. This will happen for two reasons: 1. the portions of the head adjacent to the crack are going to move independently of each other. That will cause gasket damage. 2. once the coolant is hot, and under pressure, it will start exerting a new additional force of the gasket in a direction other than normal, and that will accelerate gasket failure. That head is junk and needs to be replaced. Unless, of course, you want to get REALLY good at changing head gaskets on a regular basis.

I 100% endorse Cruiser's thought on ditching the fragile heater control valve. Those junky things do NOT age well, especially here in AZ, where temperatures really make plastic very brittle. There are those Jeepers who will prattle on about how removing that valve will allow the coolant to circulate through the heater core all the time and thus decrease air conditioning performance. While that might be theoretically possible, I cannot say that I have seen ANY NOTICEABLE difference. (And I say this as a guy who uses his AC most of the time, since I live in Phoenix.

Engines if the 2.5 and 4.0 era are virtually NEVER “interference engines”.

I remember my dad's 1968 Ford Galaxy had a PS cooler adjacent to the PS pump. It was a simple loop of tubing with fins attached to it. From that, I can infer that you probably don't need a really gigantic radiator to cool the PS fluid. If that assumption is correct, a small aftermarket transmission cooler would be more than effective as a PS fluid cooler. I would mount it on the return side of the system, where pressures are lower, since a transmission cooler is not designed to handle the pressures the the "high side" of the PS pump can deliver.

Eagle, I am a retired mechanical engineer, and while I appreciate your situation, you gotta remember that the XJ/MJ engine compartment was not originally sized to fit the 4.0 Anytime I do virtually anything on the front of an XJ/MJ with a 4.0, I start by removing the mech. Fan shroud and the e-fan. It’s a case where the front of that engine is 10lbs of s##t in a five pound box.

Here is nice short video on how to do a compression test: Compression Test

Yeah, that was the place. It was a great source for stuff.

There used to be a junkyard here in the PHX area that specialized in Jeeps. I went to them when i was looking for a sway bar for my MJ, since some previous owner had removed the one it came with . I was surprised that almost ALL of the ZJ, MJ, and XJ chassis in the yard were already missing their swaybars. Apparently, they are a hot item, at least out here in AZ.

I was gonna ask this too. The crankcase ventilation system can handle blow-by to a certain level, and then after that, it's too much, and the usual symptoms show up, like oil out the dipstick tube, leaky distributor, oil soaked air filter, etc. Tell us how healthy your rings are with a compression test.

If you can acquire a brand new ZJ bar, that would be the best choice. Since you have connections at a dealer on the west side, are you saying that a brand new OEM ZJ bar is still available? Just curious.

I would be quite surprised if a sway bar was able to be "narrowed" (as measured end to end) or "widened" due to poor recovery practices without the vehicle showing signs of damage where the sway bar is attached to the chassis. After all, this bar is made from forged spring steel. One thing I noticed is that the brackets that are welded to the axle housing, upon which the lower end of the sway bar link is attached, seem to be made from a forging, and not from a stamping. (My MJ has a late model XJ front axle, and those brackets are made from heavy gauge stampings instead of what OP's axle has.) I am wondering if those thicker brackets are part of the cause here. Is there some sort of difference in sway bar attachment points on the axle that happened over the years, or between 2wd and 4wd front axles?