Rear Main Seal. Does it need to seat ??

[gregpro50]

I have my car just about buttoned up after pulling the engine and redoing the gaskets. I put oil in the engine and noticed a small leak coming from the rear main seal. I havent even run the engine yet. Does the seal need to seat against the crank in order to work effectively ?? Also, I've heard talk about installing a sleeve on the crank before you install a seal to help prevent leaks. What is involved in doing this ??

 

[notchback]

is the seal new?

it shouldn't leak , but are you sure it didn't leak b4?

 

[gregpro50]

Yes, it has a new Felpro seal. The original one was leaking so I replaced it. Now the replacement is leaking. I havent even run the engine yet. I sealed the threads to the crank and everything. I was thinking that maybe it just had to seat against the crank from running the engine a little ??

 

[tunedin302]

Is it leaking from where it meets the crank or where it meets the block/oil pan? Also, did you clean out the mating surface prior to install? I had a similar problem and put in a new Felpro teflon seal using black silicone sealant around the outer edge. No more leaks.

 

[Rick 91GT]

It is rare to see the rear seal leak with out any run time, I would take a good look at the oil pan gasket or the intake/valve cover it may be running down.

The sleeve is only used on a damaged crank. I gave the info to tunedin302. Make sure it is all clean, put a very thin film of oil on the crank, put a thin coating of Permatex on the outside of the seal (the part that goes against the block) tap the seal into place easily, make ure it is seated and square, wipe excess permatex off, do not get any between the seal and the crank.

Put it back together, by the time you get it all together it should be set, I like to let them sit a few hours or even overnight....no more leaks

 

[BlackGT89]

If it is leaking at the crank there is a process for sleeving the crankshaft, but the tool kit maybe hard to find and expensive. Maybe you could take the block to a machine shop and let them do it while you have the motor out. Here's a link to Microsleeve: http://www.microsleeve.com/msiv03.pdf

 

[tunedin302]

I gave the info to tunedin302.

Very true. Rick was a great help and his advice solved my rear main seal crisis. Thanks!

 

[Swarzkopf]

I replaced my rear main seal last fall. I used the utmost care and caution.

I think the mother****er is starting to leak again. :rofl: I honestly am starting to think that on 5.0s that are run hard, the seal WILL leak.

If your is leaking while the engine is not running, that is bad and you should reseat it and follow these guys advice.

 

[Mavrick]

I just did mine last night. I cleaned out the recess where the seal goes, and gave it a coat of oil. I soaked the seal in oil for 20 minutes or so, and then taped it in with the old seal, and then a socket/extension to make it flush all the way around. I cleaned the outside with a little brake clean, and put a bead of silicone around the outter edge where the seal meets the block. I got a little sloppy with the silicone, so i'm going to check the rest out today, maybe clean some up if it got near the crank.

This better not leak! I've read so many horror stories about the rear main leaking right after replacement! I didn't scar any surfaces, so hopefully it'll do it's job!

 

[gregpro50]

I cant tell exactly where it is leaking from because the tranny is in but it is definitley the rear main. I took my time putting it in and made sure not to scar the crank. I cleaned the surface all out on the block with prepsol and carefully installed the seal. The only thing I didnt do was to put RTV where the seal touches the block. It doesnt leak real bad but you can see a little trickle starting down the bell housing dust shield in the front. I was just thinking it needed to seat against the crank because the new seal has little grooves where the rubber touches the crank. When I looked at the old one the little grooves were worn down and the rubber was smooth where it touched.

 

[gregpro50]

OMG did I luck out. After further investigation is seems that the crappy $50 chrome ebay oil pan didnt fit quite right to my surprise. All I did was tighten the oil pan bolts some more and NO MORE LEAK !! It must have been leaking from the back of the oil pan gasket. I'm going outside to do cart wheels in the lawn now...

 

[Mavrick]

That must be a relief.. not having to pull the tranny again!

 

[BlackGT89]

OMG did I luck out. After further investigation is seems that the crappy $50 chrome ebay oil pan didnt fit quite right to my surprise. All I did was tighten the oil pan bolts some more and NO MORE LEAK !! It must have been leaking from the back of the oil pan gasket. I'm going outside to do cart wheels in the lawn now...

Oh Lucky Day !