Replace leaking rear main seal after new build

[drdano]

I have to laugh, the "definitive guide" to FE rear main seal installation was 8 years ago.  I've learned a few things since then...

Those two tips would be good additions to that thread for folks researching how to try to do it right the first time.  ;-)

[fairlaniac]

I have to laugh, the "definitive guide" to FE rear main seal installation was 8 years ago.  I've learned a few things since then...

One of them (which isn't going to help you Doug, but I thought I'd throw it out there), is that with the engine on the stand upside down, these days I always install the crank and then the rear main cap first.  Once that is all done and sealed up, I fill the little breather hole for the seal in the rear main cap with oil.  Then I let it sit overnight.  Some of the oil can leak by the main bearing, but what you are really looking for is oil that leaks by the seal, and comes out at the rear of the block.  If you get a little puddle on the floor that came from outside the block, you have to tear the #5 cap off and do it again.  Kurt Neighbor turned me on to this method, and it really seems to help.  Kurt told me he's about 50% on this one; about half the time they leak the first time, and they have to be redone.

A couple years ago when I was assembly the dyno mule to test my intake adapters, I had to do this three times and still had a minor drip after the test.  I was pretty tired of tearing apart the #5 cap at that point, scraping away all the sealer and reinstalling, etc., so the last time I did it I smeared TA-31 on the outside of the rear main seal.  The way the seal fits in the groove in the block and the cap, I don't think oil should be getting around it, but I thought it may be possible so I put some sealer on the outside of the seal and tried one more time.  No leaks that time.  I don't know if this was due to a sub standard seal, or a block or cap that had the groove machined a little big, or what, but for whatever reason sealer on the back side of the seal solved the problem.  I imagine other people may do this on a regular basis, but I never did up to that time.  Now I do it on every engine...

Jay, when you say apply sealer to "outside of seal". Do you mean the outside diameter or the outside of the engine as shown in the picture? Thanks!

[jayb]

I mean the outside diameter of the neoprene seal, so that oil can't sneak around the back side of the seal and leak out.

[fairlaniac]

Ok, I have seen this once...
A 427 crankshaft from a CC rotation marine engine has the wee hash marks facing the wrong direction for an automotive engine. The only thing for it was to polish them right off the crank...

It's a new Scat stroker crank.

Thanks,

[My427stang]

I think the dye will guide you.

I assume the path will be pretty clear, may even want to check it before you put it on the stand, hanging there, flywheel and starter plate off, should tell you all you need to know

[fairlaniac]

I mean the outside diameter of the neoprene seal, so that oil can't sneak around the back side of the seal and leak out.

I wonder if this is something I could accomplish with the crank still installed but loosened? I'm thinking if I put sealant on the seal and fish it around the seal groove that the sealant may "squeegee" at the edge of the block?

Thanks!

[blykins]

I mean the outside diameter of the neoprene seal, so that oil can't sneak around the back side of the seal and leak out.

I wonder if this is something I could accomplish with the crank still installed but loosened? I'm thinking if I put sealant on the seal and fish it around the seal groove that the sealant may "squeegee" at the edge of the block?

Thanks!

I don't think you'd be able to apply any kind of sealant to the back side of the seal without wiping it off before you get where you going.  The seal companies supply a little cardboard tab to lay against the block so that you don't hurt the seal as you spin it around.  I could be wrong, because I don't use sealant on the back side, but I don't see it staying intact while you roll the seal in. 

[My427stang]

You could pull the crank too.  Of course that means timing cover has to come off, but not as huge deal.

I still say, come up with the plan after you see what was leaking. Thinking ahead is awesome, but the engine gets a vote

[fairlaniac]

You could pull the crank too.  Of course that means timing cover has to come off, but not as huge deal.

I still say, come up with the plan after you see what was leaking. Thinking ahead is awesome, but the engine gets a vote

Pulling the crank was my first thought until others started talking about just loosening up the crank and I like that idea a tab better. If I pull the crank and push the pistons all the way in the bore. Can I swing the rod past the journals? I'd hate to be putting the seal in, thinking I having it right and see a rod swung on the other side of the journal and I cannot get it back unless I lift the crank?

Thanks,