Is my rear main seal leaking?

[bjk_typhoon]

I have been battling with my engine builder after I removed my motor for the second time (he used the wrong head gaskets and the passenger side went). When I brought the assembled engine to him I told him that I believed that the rear main seal was leaking. He stated that it was impossible that a one piece seal could ever leak and said that he found what he believed was the leak, one of the rear plugs. After he used a large amount of epoxy on them he said that there should be no more leak (he never checked the rear main seal) now that the motor is back in I am still having the same problem.

Here is a picture after the engine was running (normal operating temp) and I wiped the bottom of the seal clean.

Here is a picture after waiting for 1 minute.

Here is a picture after 5 minutes…

Any one else experience this problem. I am not looking forward to pulling the engine for the third time just to fix an oil leak. I even took a chance and tried an oil additive to stop the leak and no luck.

 

[jwaller]

Re: Is my rear main seal leaking?

if he used a new seal that should never happen. also the rear of the crank where the seal rides must be perfect. if the old seal cut a groove in the crank that has to be fixed first. it looks like you might have to pull the eng or trans again to fix this issue. you want to be absolutly sure it's not the pan though.

 

[bjk_typhoon]

Re: Is my rear main seal leaking?

Yes, it is definetly comming from the back of the engine not the pan

 

[Try Me]

Re: Is my rear main seal leaking?

i have seen and read about engine builders using the wrong size rear cam plug. silicone will never solve that problem. engine builders user a 3/32 plug because they are super popular and they usually have a ton of them laying around. a 4.3 should have a 7/64 plug. mine had this problem when i first go the truck. i changed the plug on the last trip to the machine shop (had block decked smooth for cometics) and have not had anymore leakage from the back of the block. if yours is the wrong size, it will leak.

now, its also completely possible that a 1 peice rear seal could leak. like waller said, the crank has to be in good shape. there are actually kits that machine shops use to "sleeve" the back of the crank where the seal rides if it has been turned down for any reason. :2cents:

 

[Don W.]

Re: Is my rear main seal leaking?

Haven't done a Sy but have done others, including the old style rope seal. Done right they won't leak. The part about the correct size plug has been posted before also. Gonna have to check ;em both I reckon, sorry.

 

[UR50SLO]

Re: Is my rear main seal leaking?

BJK... I'm having the same trouble...

I had a small groove in the crank where the seal had been riding. I tried to replace the regular Fel-pro seal with the "Teflon" Fel-pro seal and it's twice as bad of a leak!!!!

I am searching for the repair sleeve that go's over the end of the crankshaft that re-news the surface so it won't leak anymore.
I just pull the transmission back and take the flexplate off. I pop the seal out and press the sleeve on. I'm searching for the sleeve now Once I get a part number I'll post it for you.

I'm talking the EXACT same problem you've got... I did a search looked at your pic's and went.. DAMN... that's what I've got going on! I just built this engine and thought I might have torn the new seal putting it in... Once I took it out I could find NO tears or flaws in the way I put it in. But it leaked. And the Teflon one leaks worse! Drips exactly like yours... then when the drip falls it splashes on the flex plate throwing it on the starter and all over the bell housing. Big mess.

So... I'll post a Part number for the fix when I find it!
Your not alone!
~Scott

 

[UR50SLO]

Re: Is my rear main seal leaking?

Ok......

After two rounds with the rear main seal issue it's solved...

There is two ways to correct this problem.

1) Felpro PN: 16258 (Crankshaft repair sleeve) and PN:16301 (Repair sleeve install tool)

2) .40 tighter rear main seal that is super soft. Made by Silver Seal products. I carry 2 here now incase any one needs one.

I installed the sleeve and new Fel-Pro rear main seal... You won't need the tight seal with the sleeve. Just a new Felpro seal is it.

I'm going to make a new thread with pics of sleeve and install tool so people can find it easy.
I keep a sleeve in stock now.. If you need one e-mail me.. I'll put the tool in if you promise to send it back
~Scott