Good Morning Ladies and Gents!


I have a 99 Cherokee 4.0L Automatic
I have a small oil leak coming from where the trans and engine meet
If I did my research properly I assume it is the rear mail oil seal
Ive already had a couple people agree with that, but Id like some more input
If that is actually what the problem is, how hard is repairing that myself?
Can anyone give me detailed list of steps on what to do?


Thanks for taking the time to read this!

 

Also, I know there is a guide for the replacement in the How-Tos section. I read through it and it doesn't seem that difficult but the guide states its a hard task. So that's a bit confusing.

 

Good morning to you too. The RMS is a common source of an oil leak, the valve cover is also a common culprit. Clean everything up the best you can to see if you can track the exact source. The RMS difficulty is relative to your mechanical aptitude. I consider myself a novice and this task was pretty simple and straightforward. Dropping the oil pan takes some time because the front axle needs to be at more than a full droop, I was doing a lift on mine at the time so I already had the axle disconnected. As far as the RMS itself, you've already seen the how-to so I won't get into that. But it was pretty easy in itself.

 

@jay sco
So disconnecting the front axle is a must before dropping the oil pan? When I replace the RMS Ill be going to the local auto hobby shop where I can use a lift and have all the tools necessary.
What else might I need to disconnect and move to get this done?




A buddy of mine who drives the same year and make said Ill have to disconnect brake lines, drive lines, drive shaft, drop the engine, axle, and the trans to get this done. Between that and reading "how-tos" that all say different things, Im all sorts of confused!!!

 

1

 

I have a 3.5" lift on mine, and just had to jack the front end up a bit to be able to clear the oil pan. I didn't take off anything besides the oil pan.

The hardest part for me was taking off the oil pan, and cleaning the gasket off. It was probably the original gasket from 1989, and it was like cement, and I ended up damaging my pan and having to replace it.

my rear main was so old and dried out it literally fell out but some people have a hard time getting theirs out.

I would highly recommend watching a how to video online on how to do the work. I think Bleepin jeep has at least one, and so does nickintime. that way you are familiar with how to do it before you get under there.

the

 

When I did mine, I already had the shocks out, brake lines off, and had the passenger lower control arm disconnected, and it was still pretty tight sliding the pan out. I guess YMMV. Your buddy that has the same year is sadly mistaken. That is the case on some vehicles, not the XJ.
Around has it right, watch videos, a few; and google it, there are many how-to's on this.

 

On a 99 chances are its not a RMS but another issue and needs a better look into it.


Most likely it will be a oil filter adapter o-ring that is bad, a dist. gasket, valve cover gasket for a few. That area around the RMS is the lowest point on the engine and any oil will run to that point. You need to clean everything on the engine very well and then keep checking where the oil is coming from.

 

I just finished my RMS and while not difficult it was not a fun job. I would absolutely check the items above before getting into the RMS.

For my RMS I had the front up on jackstands, wheels off, shocks undone, sway bar undone and still didn't have enough droop. I slid a 2x6 between the top of the brake caliper and frame rail and had someone leverage down on it, that just barely gave me enough clearance to get the pan out.

As far as other things I took off or disassembled: removed the starter motor, disconnected the steering damper and removed the lower bell housing shield. The trans lines had enough flex to move out of the way once the brackets were unbolted from the pan.

I used the FelPro one piece pan gasket that came with plastic studs to hold it and the pan in place, they worked great.

Good luck!

 

I didn't have to lift my car as I have a 3" lift. I put a junk rubber backed rug from a Goodwill store and crawled under. Pan removal wasn't hard but had to fiddle with the fit between starter exhaust. I didn't have to remove any suspension parts or brake lines; it was straight to oil pan.

 

I'd suggest making 100% sure that's where it is leaking from first. There are several far more common places XJ's leak oil from and it works it's way down small cracks and ledges and eventually drips out right in the area you are describing. I would bet 7 out of 10 rear main seal leaks I've had people ask me about turned out to be from somewhere else.

 

From Cruiser


Are YOU absolutely positive it's the rear main seal?

Here's why I bring this to your attention.

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, people on Jeep forums who can’t see your Jeep from where they’re at, 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. "$hit 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.