HighOnLift

Is my rear main seal bad?





OK yes, that is for a laugh, but what is not funny is that really is my XJ...

To get serious... how bad is it exactly? Is that gap okay (is that just the plate?) Can a bearing be completely shot to where it can never be sealed up again? Or does it look much worse than it actually is.

I plan on doing this work myself. If this was your jeep, what would you do? What is my next step here in diagnosing / repairing this? Or is it fubar?

(I'd be really surprised if anything on a jeep looks worse than it ever is)


My jeep is lifted, but this is all stock stuff going bad here so if I truly posted this in the wrong section I am sorry and will have a moderator move it.

EZEARL

The gap is how the cover is suppose to be.
http://cruiser54.com/?p=96

5-Speed

There is a chance its the rear main but a lot better of a chance that its something else. Clean everything as good as you can first. Then start with a new valve cover gasket. The one piece Felpro. Its the most common thing that leaks and looks like a bad rear main. Could also be the oil filter adapter or the oil psi sending unit.

HighOnLift

Yeah, It's super caked and messy under there so you may be right.

Any suggestions as to what to use to clean it? I do not want to use a high pressure washer since could lead to water in the motor. Any magic wipe on and wipe off stuff?

fb97xj1

The 4.0L sits at an angle, so start from the top and work your way down. This includes:

valve cover
oil filter adapter
oil pressure switch
distributor
oil pan gasket
front crank seal
rear main seal

Until you find the leak, they are all suspect. Doublecheck the transmission lines. Keep in mind that the fan will blow some of it around as you drive. So check everything.

awg

I work on greasy old engines a bit, and to ID oil leaks, it makes sense to clean the engine up. Its a mongrel of a job tho, and time consuming.

am very careful with the power washer, cover electrics in plastic and dont use it on harnesses

wipe down repeatedly with degreaser, wire brushes, rags, toothbrushes etc etc

For an engine like that, a nice warm day, you will get filthy

I understand now why mechanics sometimes become enraged when they encounter really oily engine bays

One should aspire to an engine bay that you can eat your lunch from lol

5-Speed

I used superclean in a spray bottle, wire brush for the extra nasty places and then pressure washed it. Came pretty clean after the first time but I did it twice just to make it spotless.

Whenever I pressure wash an engine, I always let it sit overnight before turning the key on and firing it up. Let's things dry out as a safety precaution.

HighOnLift

Interestingly enough, it normally sits parked at an incline and very little oil drops, but since putting inside a level floor garage, it seems that the drops are more frequent, and just sitting there not even running. I'll get a piece of cardboard under it tonight to see how much it collects.

I'm waiting for my face shield to arrive tomorrow before getting to the nitty gritty.

fb97xj1

I like the way you think. Protect them eyeballs! Got a piece of dirt in my eye once doing that without eye protection. Once.

SirCyber

Ooo engine bay cleaning! Subscribed, as I have been wondering the exact same thing with a near exact copy of what yours looks like. Only thing I have done yet to fix was my oil filter adapter (problem was successfully diagnosed and reduced drippage to virtually nil) and I have that persistant dollop of oil same place as yours and also on oil pan. Mine needs new valve cover gasket and oil pan gasket, I think

cruiser54

Just to reiterate.........

I’d be looking up ABOVE first, and VERIFYING the source of the oil leak YOURSELF.

Everybody, who doesn’t own or have to pay for or perform your vehicle repairs, loves to poke their noggin UNDER the Jeep and come out bearing the false bad news that your RMS is leaking. Many mechanics, friends, and good old Uncle Bob seem to enjoy telling you it’s the rear main seal. Has a catastrophic ring to it, doesn’t it?

A simple leak at the back of the valve cover or other source could produce the same symptoms. You don’t need to be a mechanic to figure this out. If you have good eyesight and a dim flashlight, you’re good to go on your own. Don’t jump on the RMS/oil pan gasket bandwagon right off the bat.

Almost any oil leak on your 4.0 is gonna drip from the RMS area for two simple reasons:

First off, the engine sits nose-up and any oil will run back to the RMS area.

Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber’s adage apply here: “Crap flows downhill”.

Valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket, in that order, have to be eliminated as possibilities first.

DFlintstone

Don't get the TPS wet. Both of mine had hardened adapter O rings BTW. Watch closely right away after cleaning. If you drive a few blocks oil can blow all over and you are back near where you started.