Rear main seal leak

[bc69]

Fresh motor rebuild and on start up rear main seal leaks (drips) at a steady rate above idle. At idle it will stay dry. Has a new fel-pro 2pc seal, gray one that came with gasket set. Staggered ends with no sealant on ends. Did seal main cap at recommended points.

Brad

[Kelley W King]

We assume you lubed it to prevent dry start up?

[bc69]

Sure did.

[Stingr69]

Rear seal leaking or maybe pan gasket?  Lip in or out?

I always add a tiny amount of sealer to the edges regardless of what it says. They have never leaked.

-Mark

[bc69]

Thought that I might have got it in backwards, dropped pan and it was in right, so now what, went and picked up another seal, this one was blue in color and looked to be a little heavier seal. Rolled it into place and it had more crush than the other. The gray one had next to not pressure on the crank.

[bc69]

Just got it running again and no leaks yet. Gray Fel-pro 2 piece seal was the problem!!!
This crank has never been touched other than being polished just before assembly. So anybody installing a new rear 2 pc seal, I suggest that you roll it in and check that the lips have a good amount of pressure or crush on them before installing the rear cap.


Brad

[sdkar]

Not to get too far off on the rear main seal leak...but for anyone who thinks they have this type of leak, try checking the oil pressure switch that is just behind the distributor and directly above the rear main seal.  I have seen several times where there is a leak and it is thought that the problem is the rear main seal and it's not.  Huge difference in the amount of labor in repairing either of these problems, so I suggest you check first.  Just something I learned the hard way myself and figured I would pass the lesson along.

sdkar

[bc69]

Well.......does anybody have a remedy for a still slightly dripping rear 2 pc seal?
Down to random drip.
After 2 not doing anything else until listening to a number of suggestions.
Do they make a different style of the old two peace?

[JohnZ]

Well.......does anybody have a remedy for a still slightly dripping rear 2 pc seal?
Down to random drip.
After 2 not doing anything else until listening to a number of suggestions.
Do they make a different style of the old two peace?

There are two rear main seals besides the standard silicone one (Fel-Pro #2900). The #2912 is made of fluoroelastomer (more expensive), and the #BS-118291 has an offset double lip if the original seal has worn a groove in the journal (also expensive).

[Dave69x33]

JohnZ,

So would you recommend the Fel-Pro Rear Main Seal #2912 if the journal is fine with no warn grooves?

Anyone else have a good experience with this seal?

My '69 302 was rebuilt about 10 years ago and only has been driven about 2000 miles.  I have developed a rear main seal leak, and a leak from the timing chain cover to oil pan joint.  I used a Fel-Pro blue one piece oil pan seal, but it just started a slight oil leak. The leak appears to be coming from the oil pan side of the seal rather than the timing chain side or seal joint.

I guess it’s time to pull the engine, reseal and detail it again.

Thanks,

Dave

[Charley]

Another thing to do when fighting oil leaks is to make sure the breather system is working correctly. Excessive crankcase pressure can cause all kinds of leaks.

[bc69]

Cost of the seal is the least of my concern. I do not want a leak and after all this, as I said, I want this next time to solve the problem.
 Sounds like the #BS-118291 is the best way having what one might call a backup lip?  Or would one suggest the #2900?

[JohnZ]

Cost of the seal is the least of my concern. I do not want a leak and after all this, as I said, I want this next time to solve the problem.
 Sounds like the #BS-118291 is the best way having what one might call a backup lip?  Or would one suggest the #2900?

If you don't have a groove worn in the main journal, I'd use the #2912 instead of the #2900; it's a better seal.

[bc69]

Will check it out and appreciate the input. Anybody else have anything to add, please do.

[bc69]

Thanks johnZ.
Installed 2912 seal over year ago and still dry!
bc69