Rear Main Seal and Oil Filter Adapter Question
 

Rear main seal was replaced a few months ago.

Now, oil is dripping from the back of the oil pan where it covers the rear main bearing cap, and down on to the bell housing.

I've seen the post about eliminating the other leaks first before assuming it's the rear main seal. IF IT'S DRIPPING FROM WHERE THE OIL PAN COVERS THE BEARING CAP, DOESN'T IT HAVE TO BE EITHER THE REAR MAIN SEAL OR THE OIL PAN GASKET THAT IS LEAKING????

When we did the rear main seal, we did not wait 24 hours for the RTV to dry. Could this be the problem?

Are you saying you have NOT eliminated the oil filter adaptor o-rings ?

this potential source of leak must be eliminated before anything else, and if not changed out, should be assumed to be leaking

the suspect areas should be made utterly clean with degreaser and cloth

run the engine for a minute or two...examine for leak source

the oil filter adapter seems to be seeping, not dripping. I dont think its possible that a leak from the oil filter adapter can drip from the middle of the oil pan where it covers the rear main bearing cap ????? Is that possible??

Fix the adapter leak and find out! It could be coming down the back of the block from the valve cover where you can't see it.

Valve cover is a real possibility.

But, I'm in the camp that says do the obvious first. and the easier stuff, especially if it's leaking there. ever read my little diddy on diagnosing oil leaks?

If you do the adapter oring and use a retching wrench use one that's reverse-able that bolt is longer than what you think. Ask me how I know lol!

Very possible. The engine sits with a downward tilt to the rear. Nearly every oil leaks runs down to the rear of the engine and can look like a rear main seal leak.

Oil leaks from the valve cover will eventually collect on the bell housing, rear main, oil pan, and even the oil filter adapter. Anywhere, really. Like said, the engine sits nose up so leaks will work thier way back, and down. Thats gravity at work. When you drive, the rush of air blows the oil around so finding oil on one or the other doesnt mean much. You still have to find out where its coming from. It could be a leaking valve cover doing it all, and the rush of air is redistributing it. Same with any vehicle.

If you clean the adapter area well...you should be able to see a leak big enough to drip off the bellhousing...that's not to say don't replace as precaution but sometimes that doesn't go to well if its really not leaking. the back of the valve cover is definitely a possibility...its very hard to see. Did you use the really nice blue felpro or something else . Pull the access cover off the bellhousing plate to see the flexplate...if that's really wet it could be the rms or it still could be the valve cover...the valve cover gasket is WAY less expensive to try than fixing the rms so I would try that first...there a two bolts at the back of the valve cover that are tough to get at...are they loose

X2 on valve cover leaking looking like a rear main seal. Stick you hand behind the engine and see if it's oily between the trans and the valve cover.

My XJs valve cover was leaking so bad that it left a 3" diameter spot on the tarmac every time I parked it, but I didn't see any oil around the cover. It was leaking just in the back where I couldn't see it at all. After fixing that AND the adapter, it doesn't leak anywhere.

Do I need to post this again?CRUISER'S MOSTLY RENIX TIPS

REAR MAIN SEAL DIAGNOSIS

OCTOBER 31, 2015 SALAD 3 COMMENTS EDIT

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. A little tip here. Rather than use a dizzy gasket, use an o ring instead. NAPA #727-2024. Tips 12 and 13 will help you get your distributor back in place correctly.

If you do end up replacing the VC gasket, I highly recommend Fel-Pro #VS50522T PermaDry. I used it on my 91 4.0 and never had a leak at the VC again. Costs a little more but lasts WAY longer and really seals the VC to the head surface.