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Significant Oil Leak after new RMS

M

Matthew89

NAXJA Forum User
Location
Mississippi
'99 w/ inline 6. Lots of heartbreak today as I just wrapped up my RMS job and realized I have a pretty bad leak. It was a small drip before so figured I'd finally take care of it (right before a big trip like a dumbarse) and now it's quite a bit worse. Wish I had just left it alone.

To save some time, here's what I did once I had access to my bearing caps: I dropped the rear one and gave the upper seal some light taps with a small flat punch. It didn't move and I was really afraid of my punch slipping and damaging the crankshaft. So I loosened up on the next few bearing caps until I was able to simply push the upper seal out by hand with the punch. I then moved to the lower seal. When I pulled it out it left a lot of material behind. I very carefully scraped out the groove with my pocket knife (the edge, not the point). Wondering if I screwed up here, but I was really tedious and didn't gouge the metal.. But I'm obviously questioning it now.

On to install: I soaped the backside of the upper seal and applied motor oil to the inside. Installed it as instructed without much trouble. On the bottom seal, i lightly soaped it's outside as well, applied a small amount of RTV to the ends, and put a light coat of oil on the contact portion. I put assembly lube on the bearing and put it all back together. 80 ft lbs on the bearing caps.

I put it all back together, filled her up, and started it. I let it run for several minutes. Oil pressure looked great and there was not a single sign of leaking below. However when I went for my victory drive, I returned to find a really steady drip coming from between the transmission and the cover plate that sits between the engine and tranny. I threw a pan under it and went to get a beer and cry a bit.

The leak subsided within about 10 minutes of letting it rest, but I feel pretty confident it'll come right back if I drive it again. Although I'm willing to test that if any of you think I should for some reason.

What could I have done so wrong? I really took my time and followed several resources- Haynes and the write up by 5-90 on here. This is not my first big job, but it was my first RMS.

I've still got time to do it again before the trip, but apparently I'm missing something here. If anyone has ideas, suggestions, questions, etc. I'll be watching closely. I've got to either get this straightened out or book a flight, and I hate flying.

Thanks guys.

Edit: one other thing is I may have let the RTV setup too long before putting the lower cap back on. It was still tacky but not right out of the tube. Also wondering if I used enough. I didn't goop it on. Could a poor RTV job be the culprit, I wonder? Just a thought.
 
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Yeah I'm positive. It had a leaky VC when I bought it. I replaced it with a Felpro 2 years ago and it's been perfect since. Plus the oil is very clearly pouring from the tranny bell housing. It also used to show signs of oil on the flywheel after setting up for a while (crappy clutch engagement on first few takeoffs).

Edit: to be quadruple sure, I just went and ran my hand behind the valve cover and it's bone dry.
 
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Mis-aligned rear Pan gasket leak? Loose, or missing a pan bolt?
 
Thanks for the response. Definitely no missing bolts. But I'll be sure to inspect the rear part of that gasket when I drop the pan in the morning. I could definitely see it potentially getting misaligned. I've kind of got doubts though because the oil is pretty obviously coming from behind that bell housing plate rather than trickling down the front. Now if it could come from the oil pan gasket and get behind the plate, then it's a possibility. What I will say is I can't see oil spinning off the output shaft when I look through the tiny gap into the bell housing with a flashlight (while it's running and leaking) so that would kind of support the oil pan thought.. But everything is moving so fast I probably wouldn't see much anyway and again I kind of figured oil pan leak would run down the front of the plate not from behind. This leak is freaking huge whatever it is. Like teaspoon per minute.
 
Looks like a re-do, perhaps
 
Already picked up a new seal and took off work tomorrow in preparation of that possibility.

Any other comments on the feasibility of an oil pan leak making it into the bell housing? I'm trying to remember the exact layout of things in that area.
 
Did the follow the instructions in the Fel Pro oil pan gasket package? I did not read where you put Mopar gasket maker or equivalent at the 4 required places on the oil pan gasket. Two of those places are where it bends up and around over the rear main bearing cap. The other two are where the block ends and the timing cover starts.
 
Matthew89 said:
On to install: I soaped the backside of the upper seal and applied motor oil to the inside. Installed it as instructed without much trouble. On the bottom seal, i lightly soaped it's outside as well, applied a small amount of RTV to the ends, and put a light coat of oil on the contact portion. beer and cry a bit.
Click to expand...

Soaped? Never heard of that! Did you seal the ends of the seal or stagger them?
 
RedHeep said:
I did a rear main seal once and royally screwed up the pan gasket. Oil poured out of it.

It's easy to get that pan gasket screwed up.
Click to expand...

This! PO on the wife's Jeep did exactly that. It puked. The only other thing is to make sure you put the rear main in the correct orientation, or it'll leak like crazy.
 
md21722 said:
Did the follow the instructions in the Fel Pro oil pan gasket package? I did not read where you put Mopar gasket maker or equivalent at the 4 required places on the oil pan gasket. Two of those places are where it bends up and around over the rear main bearing cap. The other two are where the block ends and the timing cover starts.
Click to expand...

My gasket instructions said to put RTV around the 4 corners. I didn't use nearly enough though. I re-did the oil pan gasket yesterday and just went ahead and did an entire bead around the top and bottom of the gasket, like user 5-90 suggested in his write up. It's had 24 hours to cure now so as soon as I leave work I'm going to test it out again.
 
trippled said:
This! PO on the wife's Jeep did exactly that. It puked. The only other thing is to make sure you put the rear main in the correct orientation, or it'll leak like crazy.
Click to expand...

I've realized this is potentially what I did as well, so I took it back apart yesterday but just re-did the oil pan gasket, with more attention to detail. I admit I kind of rushed that part the first time. I'm going to rule that out before I tear back into the RMS.
 
Green XJ Jeep said:
I made the mistake of not using black silicone one time which led to a redo.
It sucks but sometimes it happens

Make sure your pcv system is functional.
Click to expand...


Thanks, I am keeping the PCV system in mind as I troubleshoot. In hindsight I think I used very insufficient amounts of RTV. I re did the gasket yesterday, new gasket and full bead of black RTV on top and bottom. Was very careful placing the gasket. I left the RMS alone for now. We'll (hopefully) find out tonight if it was just the oil pan or something more.
 
Thanks for all the responses. Looking back, I didnt use very much RTV on the corners and may have misaligned the rear portion of the gasket. When I took the pan back off I could see what appeared to be signs of oil seeping out of the back. I went and bought a new OP gasket and a full tube of black RTV and re-did the oil pan. This time I ran a continuous bead on top and bottom of the gasket, and was very careful installing it. I'm about to leave work and go test it out now that the RTV is done curing. I'll let you guys know what I find.
 
Update (Solved):

Hey everybody, it was the oil pan, not the new main seal. I bought a new pan gasket and redid it with a full bead of RTV on both sides of the gasket. Then I used the included pegs to install the gasket and then very carefully slipped the pan on last then let the RTV cure. I filled it back up with oil this evening and have now driven about 15 miles and it is no longer leaking. I'll keep putting miles on it and watching it but it's holding good so far. I just did a really crappy job installing the oil pan the first time. I've gotten spoiled using Felpro gaskets elsewhere with no RTV and didn't take it very seriously when they "recommended" it here. I put some small dabs on the corners but nothing like what should have been there. I can't see any reason now not to recommend others do a full bead too, but that's just me. Maybe it's not necessary. As I'm sure you all know, it also takes a lot of attention to keep the rear part of the gasket aligned properly, even with the pegs. I'm not sure I had that right either the first time. It's so good to have my Jeep healthy again. Thanks for everyone's input, I really appreciate the knowledge base here on NAXJA.
 
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