F*&k, I think my brand new rear main seal is leaking!!

[gryt57]

I did not replace the side seals. I've got some, looked at them and opted not to disturb them. This rear main seal wasn't leaking until I proactively replaced it during my clutch install a few months back. If I'm looking at it correctly, I don't think the cap is leaking on the seems that I would presume the side seals to seal. Once I got the fly wheel off, it was very obvious that the rear main is the culprit.

On the crank, you can't feel any wear, but I can see a dull area that i presume is where the seal was riding.

Another thing. On the last seal install I didn't think to smear a bit of oil around the inside of the seal that rides on the crank. I wondered if a little friction on it on first start up caused any issue? Again, there is no visible indication on the new seal for why it was leaking.

This time I would clean the end of the crankshaft, with some type of a solvent. Put some type of lubricant on the inside of the seal, and the outer edge, moly grease or petrolleum jelly, according to the book I am using to rebuild my engine. Its possible with no lubricant the inside of the seal lip it tore slightly, or maybe the lip did roll slightly.

[cozye]

Got it all put back together tonight.

I'll say this. I compared the new/leaking seal against the brand new felpro I got to replace it. The new leaking one is thinner, and the sealing lip that rides on the crank is like half the size. the diameter of the opening is wider as well. When I held the felpro against it with the old one in front, there is a lot more lip material on the felpro. In addition the lip is wider and the whole seal is thicker/deeper. I'm fairly confident it will do a better job.

The new/leaking/old one, whatever you want to call it, came from MSA and is the national brand.

It will probably be a couple weeks before I can puts some miles on it to find out, we had some more snow and there is still a slight amount of salt on the roads. I'm waiting for a rain to wash it off before I drive the car some more.

[gryt57]

Got it all put back together tonight.

I'll say this. I compared the new/leaking seal against the brand new felpro I got to replace it. The new leaking one is thinner, and the sealing lip that rides on the crank is like half the size. the diameter of the opening is wider as well. When I held the felpro against it with the old one in front, there is a lot more lip material on the felpro. In addition the lip is wider and the whole seal is thicker/deeper. I'm fairly confident it will do a better job.

The new/leaking/old one, whatever you want to call it, came from MSA and is the national brand.

It will probably be a couple weeks before I can puts some miles on it to find out, we had some more snow and there is still a slight amount of salt on the roads. I'm waiting for a rain to wash it off before I drive the car some more.

Coyze,

I purchased a complete Itm rebuild gasket kit from the machine shop that did all my machine work on my motor. The side seals in that kit were not a tight fit and did not come with the expanders either, I bought a felpro rear main seal kit.

The side seals in felpro kit fit so snug, I could not even put the expanders in, I installed the rear main seal from the itm kit, and was thinking of pulling the itm seal and installing the felpro seal when the motor is off the stand. After reading your post I will use the felpro rear main seal.

[cozye]

gryt, I'll post back up as soon as I'm sure it's not leaking. Last time I put the seal in I looked at the clymers manual and it didn't say anything special. This time I looked at the FSM and as you suggested, it recommended oiling the crank surface, the outer edge of the seal, and used lithium grease on the inside lip of the seal. I'm sure it will hold up now..

[gryt57]

gryt, I'll post back up as soon as I'm sure it's not leaking. Last time I put the seal in I looked at the clymers manual and it didn't say anything special. This time I looked at the FSM and as you suggested, it recommended oiling the crank surface, the outer edge of the seal, and used lithium grease on the inside lip of the seal. I'm sure it will hold up now..

That would be great, I am probably a week away from installing the motor back into the car. Then, what I think will be my biggest challenge, wiring everything back to make it start and run properly. I am rebuilding a 82 280z turbo motor to put into my 78 280z.

[madkaw]

Well my leak was also the dreaded rear main. When I got the flywheel off I could see oil puddled on the bottom of the seal. What I also noticed was that the inside diameter of the seal was actually cracking-like as in dry rotting. There was cracks all the way around the inner diameter which certainly weakened the seal. I have 3000 miles on this rebuild, so i guess the seal was bad from the get-go. There was no scarring on the crank-until i pryed off the seal and then i knicked up the crank near the end. Fortunetly, it should not be anywhere where the seal rides.

Bo, you said you don't bottom the seal out or push it all the way in? It seems to me that the seal was made to be pushed all the way in against the block-that way you know you have it in squarely.

[cozye]

Jury is still out on mine. It did leak a little on my long test drive, but I had a smear of lithium grease on it that may have allowed a little to seep out until it wore off. I haven't been able to drive for over a week. I'll probably get to drive it some later this week though.

[cozye]

Still leaking slightly. I give. I'll drive it for a while and see how it goes. I still have the seal that just came out and can see no reason why it leaked. The new one did have a smear of lithium grease in the grove between the lips where the crank rides (as suggested by the FSM for installation), I thought maybe while that grease was in there it was allowing oil to seep out.

It shouldn't be that difficult. This should be a simple thing.. sigh.

[cozye]

Just to close the thread for future searches. It was the side seals on the rear main cap that were leaking. Replaced them earlier this week and problem is finally solved.

[madkaw]

Well I guess i am on the same path as you because my car is still lealing in that corner, so it must be the side seals---which for life of me can't remember anything about them. So I need to pull the oil pan to fix these??????-someone enlighten me please.

[cozye]

Yes, you will have to pull the oil pan. The side seals are on the back part of the block, pushed into 2 square slots in the rear main cap. You can probably dig out a little of the rubber, and grap ahold of the "nail" with some needle nose pliers and they should slide right out. If you fail to get them out that way, you have to pull the rear main cap off which may require a puller or some ingenuity. It's pressed in pretty tight but has two bolt holes that you can thread into and use a home made puller.

I obtained some OEM style side seals from MSA. I would recommend these as they are made with the rubber molded to the nail. The nail is a small piece of steel that runs the center of the seal to hold it's shape while you tap it in. The Felpro oil pan gaskets come with side seals, but they are a flimsy rubber seal that comes with a separate flat piece of metal that you have to wedge in. It would be much harder and possibly not work correctly if you tried to install these. They may work ok, but I was real glad I had the OEM style once I got in there and figured it out.

I've been able to remove my oil pan twice without raising the motor. It may not be the same on the 240, but on the 280 if you put #1 piston a TDC to get the crank out of the way, you can loosen the oil pan and turn it sideways slightly and drop it right out. The oil pan gasket sticks to the block like glue, so once you remove all of the bolts, it will take some patience with a putty knife to break the seal loose and work the pan off. Both times I've put my oil pan gasket back on "dry" without any cement. I think the primary purpose for the cement is to hold the gasket in place while you put the pan back on, but it's not really necessary IMO if you just make sure you line up all the bolt holes and put the bolts in loose until everything is lined up.

It's a 2 hour job total including cleaning the old gasket off, etc..

[cozye]

also, when you pull the old ones out, pay attention to the orientation. The nail is not exactly in the center and the seals have some groves in that are directional. There is a correct orientation.