aa7kn

I have a 1991 XJ 4.0 6cyl. manual tranny. the oil drain bolt always drips and is making me crazy. I have pressure washed the engine to make sure the valve cover or the oil filter adapter are not what is causing the leak, they are all dry. I was thinking of changing the oil pan. how difficult is this to do with the engine still in the car ? it looks like it should just unbolt and come out since the sump is behind the axle, but I am not sure...any thoughts ? I have already tried changing the drain bolt 3 times with different bolts from the local junk yard, but every one I get, even a new one slides into the hole, mine is a odd size bigger for some reason and I can't seem to find a correct bolt. thanks in advance and I hope to hear from you guys soon.

93_xjcherokee

Have you tried a new gasket on your factory plug?

madmanmarty

Yep,or aluminum crush washer.

Oswalla

If you still have threads to bite, wrap with white plumbers tape plus new gasket. If you can't get it tight, Napa sells oversize aftermarket oil pan bolts.

aa7kn

did all that. I just crawled under the Jeep and it really doesn't look like the drain plug is really leaking, it looks like it is leaking between the transmission and the back of the motor...I hope it isn't the Rear main seal. but it looks like it is. has anyone done it with the motor in the car and how hard of a job is it ? I have seen guys do it on you tube but want to ask here if it is a Do it your self job or should I put it in a shop. I am just concerned that if someone else does it it won't get done correctly so I want to do it my self....how big of a job it is ? Thanks

cruiser54

See how tight your rear valve cover bolts are.

BlueRidgeMark

Everything looks like a rear main seal leak.


Valve cover, oil filter adapter, you name it, it runs down and drips there.


So, Step One is to clean everything from the top of the engine down, and find out where the leak really is.

cruiser54

Hey Mark. Good morning.

That's why I wrote this:




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.

Revised 02-26-2013

BlueRidgeMark

I was hoping you'd post that, but I guess you were sleeping in....

cruiser54

Yeah. LOL. You're welcome to save this stuff and post it or refer folks to the proper Tip at www.cruiser54.com.

aa7kn

well I think the I got it fixed thanks to all of yours comments. I did find several of the valve cover bolts lost( from 1/2 turn to 3 turns loose) I tightened them up and cleaned everything real well, and I don't seem to get the drops on the ground anymore. Thank you all for your input.

cruiser54

Well, imagine that!! LOL.

Always go simple and cheap first.

BlueRidgeMark

That was my wife's motto before she married me.

aa7kn

well although the valve cover bolts were loose they we not the cause of the oil leak...I still had some dripping now and then. I also noticed the oil smelled more like Gear oil and not motor oil. the only source of gear oil leak would be the front input shaft seal on my AX-15 transmission. so I think that is my problem. I will have the seal changed and see if that fix's my problem.