Oil pan gasket

[northplainsdrifter]

I'm having a hell of a time trying getting the rear of the oil pan to seal up. I can't get the rear rubber seal to stop leaking. I've been putting gasket sealer on the edges where the cork and the rubber come together. I'm begining to think it's the gaskets themselves, I've been using NAPA brand. If anyone has some hints or a better brand, I'm all ears.

[jeepsr4ever]

Loosen the pan and make sure you have no oil on the back rail. Run a thick bead of silicone on the back radius of the oil pan and let it completely hardned and then tighten up.

[northplainsdrifter]

Thanks, I'll give it a try!

Edit - Do you still use the rubber gasket?

[Patf10]

i think they make 1 piece gaskets for everything but amc V8s id kill for one of them

[jeepsr4ever]

Depends on the build. I really dont like to use rubber in front or rear of the oil pan or intake.

[tufcj]

Are you sure it's the gasket and not the rear main seal? The leaks they cause look a lot the same. I had a rear main go on a 304 once.

The rubber end gaskets go in first. I set the cork gaskets on the block with Permatex weather strip adhesive, then a dab of RTV where the cork and rubber meet. Never had a problem with leaking.

Also, make sure the bolt holes aren't "pulled" from over tightening. If they are, hammer them back to flat. It doesn't take a lot of torque on the pan bolts, just enough to see the cork squeeze a bit.

Bob
tufcj

[northplainsdrifter]

I thought it was the rear main too, I replaced that at the same time. I even hammered the bolt holes flat. The rear rubber gasket from NAPA is almost too short, either that it's such a tight fit into the bearing cap that I didn't get it in all the way. That's why I was wondering if they are all that way or just NAPA.

[AMX69PHATTY]

When installing the Crank Rear Main Bearing Cap, there is a small chamfer at both ends of the bearing cap along the outer bottom forward to aft running edges where the cap meets the machined pocket in the block. The TSM says to use a small amount of sealant (silicon) along both of those small "lead-in" chamfers. Another area to Seal besides the Rear Main Seal and the Rear Oil Pan Seal. Just a guess.

[northplainsdrifter]

Thanks for all the tips, I'll try it again this weekend. I'm thinking the rubber gasket must have slipped during the install. It's really difficult to see because of the plate between the block and bellhousing. I replaced it a couple years ago and it was just getting too bad, so I'll try it a 3rd time... I've looked for 2 days and I think Felpro is the only maker of AMC pan gaskets, now that's weird!

[northplainsdrifter]

I'm still having a hell of a time getting the rear of engine to quit puking oil! I redid the oil pan gasket AGAIN and the same result. Oil just pours out the back. It looks like it's coming from the oil pan but I can't see why it would as I was really careful putting everything back together. I read an old manual and it stated that I should use Permatex #2 on the bearing cap being careful not to get any on the ends of the rear main seal. I did replace the seals but did not use any type of sealer on the rear main cap. Could this be my problem?

[AMX69PHATTY]

Other possible areas in the rear of the block are the two oil galley pipe plugs and camshaft freezeplug ?
Or maybe the rear intake to block horizontal seal ?
just guessing

[northplainsdrifter]

I looked at the intake and it's fine. It doesn't look like it's coming from above the crank but it's really tough to see up there. I pulled the inspection plate off and the oil is dripping from the bottom side of the oil pan where the rubber gasket sits, it's running down to that point. Someone suggested to me that the crank could be wore out and a groove has formed where the main seal is letting it leak past the new seal. I will look at that when I pull it apart AGAIN.

[tufcj]

The 2 rear mains that I've seen go bad have both been the top (block) half. You have to be very careful and use plenty of lube when replacing it so it isn't damaged while sliding in. Also, are you sure it's installed facing the right direction (lip toward the inside of the motor)? The top half can be installed facing either way.

Bob
tufcj

[northplainsdrifter]

I swear I put the top one in correctly, but will recheck it. I DIDN'T loosen all the main caps and drop the crank a bit to slide the seal in. Is that necessary?

[tufcj]

I've done it with just the rear main cap off. Just need lots of lube and ease it in. Wait... what are we talking about.... :shock: :shock: :-| :-|

Bob
tufcj

[JERSEYJOE]

I always loosen all the mains caps to drop the crank enough to take the pressure off the upper main seal. With the pressure on you could rip the seal, plus withth ecrank dropped a few thousands it will then push in with your finger as opposed to banging it in. Someone mentioned the use of sealer on the edge of the main cap where it fits in the block. VERY IMPORTANT. This is one of the most challenging aspects of the AMC V8: GETTING THE REAR SEAL AND PAN TO NOT LEAK. LOL LOL LOL.

I have been working on these since 1975 and every once in a while a have to redo one. Most difficult in the chassis.

Use lots of brake cleen and make sure there is no oil residue where you put the silicone.

[northplainsdrifter]

Thanks for all the tips!
I put a new rear main and pan gasket in a few years ago with good luck the FIRST time. This is really starting to tick me off as I have been VERY careful putting things back together. I didn't know about the sealer on the main cap and suspect that is where my problem is. I'm going to start from scratch AGAIN and very carefuly inspect all surfaces and use the proper sealant where needed. Hopefully next time you hear from me it will either be fixed or in a million damn pieces! ](*,)

[JERSEYJOE]

Don't feel bad. As I said I have had to redo these from time to time and I am sure any experienced AMC mechanic if he is honest will admit that he has had to redo a leaker.

Let us know how you make out.

[northplainsdrifter]

:!: :!: :lo1l: :lo1l:

Yippe yahoo and all that crap! The other night I crawled back under the CJ to attack that damn oil leak for the 3 third time and by gawd I fixed it! It's about damn time too, not a single drop after I drove for about 20 minutes! :?

This time I loosened ALL the rod caps and popped the crank down a bit then slid the new upper rear main in. I used Permatex #2 and put a small bead in the rear bearing cap where the lower main seal goes paying lots attention to how everything was lining up. Then put a small amount on the bearing cap being careful not to put any on the ends of the rubber rear main seal ends. I also used the #2 sealant on the rear rubber pan gasket between the bearing and the seal. Put the cork seals in place with silicone in the corners where it all meets. Put the pan on and waited, no wait, I prayed for 24 hours and then took it for a spin last night and no leaks! :t:

[tufcj]

:lo1l: :lo1l: :lo1l: :t: :t: :t: :t: :!: :!: :!: :!:

[JERSEYJOE]

Glad to hear it has stopped. It's that little bit of sealer on the chamfer that does the trick.

[nico]

any pic of this? I put on new seal and new gasket , ran for å few miles then started to leak. Going to put in new seal now.

[northplainsdrifter]

Sorry, I didn't get any pics because the oil kept getting on the lens. :smile:

If you read one of my last posts, I started from scratch and made sure everything was lined up. I also learned that if you use TOO much gasket sealer that it just makes things worse as it all just sldes around.

Good luck!