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

[cozye]

Ok,

What did I do wrong? A couple months ago I replaced the clutch, put a brand new rear main seal in as preventative maintenance at the same time. The old one wasn't even leaking. How it appears that I have oil seeping down between the aluminum bell housing shield plate, and the block right behind the oil pan. It's a slight possibility that my oil pan gasket is leaking on the back edge, but I don't think so. The oil is running down that back corner and dripping off the bottom of the tranny.

The old gasket I pried out with a screwdriver. The new seal I lined up and gently walked it around with a socket extension and tapping.

It does leak just sitting still, but I don't know if thats because oil pressure fills up the area behind the block in between the plate and the block while running, and then it just seeps out while sitting.

What can I do to ensure that a replacement will not leak again? If I'd have left the old one in there, I would be good

Also, whats the olds that my new clutch will get oil soaked? I figure that plate behind the fly wheel is designed to keep oil from blowing back up in the clutch anyway, that it's probably just seeping down behind the plate.

[sblake01]

Did you point the sealing lip toward the inside of the engine? Or put a little silicone sealer on the rear main cap?

Edited December 30, 2010 by sblake01

[cozye]

Did you point the sealing lip toward the inside of the engine? Or put a little silicone sealer on the rear main cap?

Are you referring to the orientation? New one went in the same way as the old one.

Rear main cap? I don't think I have one? It was just the seal.

I should quantify the amount of leakage. We are talking about a dime to quarter size spot per day, so it's not huge. It wasn't leaking at all before the replacement though.

[cozye]

Also, the replacement was from MSA.

[steve91tt]

Could be the rear main seal but there are a couple of other things to consider...

Are you sure it's engine oil? I had a transmission input shaft leak that produced oil in the same way with the exception that a transmission leak will generally not produce oil unless the car is run.

There are also oil seals around the rear main cap that can leak engine oil from that part of the drive line. I've had that leak too. When mine started leaking I thought that it was my rear main seal but it wasn't the case. It was just the two little rubber seals. Unfortunately to get at them you have to drop the oil pan and pull the rear main cap. Not as bad as it sounds.

just my $0.02

[sblake01]

Are you referring to the orientation? New one went in the same way as the old one.

Rear main cap? I don't think I have one? It was just the seal.

I should quantify the amount of leakage. We are talking about a dime to quarter size spot per day, so it's not huge. It wasn't leaking at all before the replacement though.

It's been a while since I've done a Datsun rear main. I'm probably thinking V8 in my response but it should be about the same. Main cap is part of the engine. The seal seals against it. Edited December 30, 2010 by sblake01

[cozye]

Could be the rear main seal but there are a couple of other things to consider...

Are you sure it's engine oil? I had a transmission input shaft leak that produced oil in the same way with the exception that a transmission leak will generally not produce oil unless the car is run.

There are also oil seals around the rear main cap that can leak engine oil from that part of the drive line. I've had that leak too. When mine started leaking I thought that it was my rear main seal but it wasn't the case. It was just the two little rubber seals. Unfortunately to get at them you have to drop the oil pan and pull the rear main cap. Not as bad as it sounds.

just my $0.02

Steve,

It's oil. Also the tranny shaft was dry when I got it out, and if it was the tranny I think the leak would be comig out the weep hole in the bottom of the bell housing. It's definitely coming from the front side of the aluminum shield against the block.

Those two little rubber seals. MSA recommended getting them, so I have them. But when I did the clutch job I couldn't find the "side seals" and moved on. I do have an oil pan gasket I plan on replacing first. Will I be able to replace these side seals then, and would that leak come from the rear main seal area? This is a possibility I reckon. Could driving the rear main seal in disturb these side seals ?

ON the oil pan, I thought it was an easy job? I figured just putting #1 at TDC to get the crank lined up and i should be able to pull the pan without much effort right?

[Jeff G 78]

Stephen, if he was just doing a main seal, he shouldn't need any sealer. It is only needed when the pan or main caps are removed.

cozye, my only guess is that the lip got knicked when you put it in. If it IS engine oil and not gear oil, you are pretty much screwed and will have to pull the trans again. Rear main leaks only get worse and the oil can ruin your new clutch. It really sucks, but you should pull it soon.

[sblake01]

The side oil seals will be accessible when the pan is off. Driving the rear main seal wouldn't disturb them. I'm pretty sure you'll have to lift the engine off the mounts to remove the pan. I would check the seal again, as Jeff suggested, before doing that.

Edited December 30, 2010 by sblake01

[cozye]

Ok. Thanks for the input guys.

Any other tips or suggestions for making sure I get good results on the reinstall of the seal? Should I try another brand other than the one provided by MSA ?

[Jeff G 78]

The MSA seal should be fine, but you might also check with www.rockauto.com. I have been buying all my parts there lately with great success.

Before you install the new seal, run your finger around the crank and feel for any burrs or grooves. If you find any burrs, sand them off. If you find grooves, install the seal slightly inboard or outboard to avoid them.

[cozye]

I've bought quite a few parts from Rock Auto lately too. They list Beck Arnley, Felpro, and National (which is what the MSA one was I believe). Which brand would be the best ?