hey guys my engine has about 300 miles on it since rebuild, and the rear main seal is already leaking, only thing different about this bottom end as opposed to the last engine is its a 4 bolt main and the oil cooler was removed for the clearence of kooks headers, im not sure what oil pump or spring in the pump i have at the moment. I currently have almost 80psi oil pressure on a cold start and it goes to about 50 or 60 when warm or cruising warm. Is it possible the high pressure is causing the rear main seal to leak?

 

Thats always a possibility. too much oil pressure, oil will just take the weakest route out. or too much blow-by. Your oil pressure is way outta specs too.

Normal Oil Pressure, PSI Minimum, 6 psi @ 1000 RPM; 18 psi @ 2000 RPM; 24 psi @ 4000 RPM

 

24psi at 4,000rpm? While they may call those values "minimum", they are far from "normal" on an LT1. New, my stock engine made 30+psi at idle, 40psi at 2,000 rpm and ran right up to the relief spring pressure above 5,000rpm.

I run a high pressure pump (80psi) on my current setup with no problems at all. But the engine was built knowing that it would run the high pressure pump.

 

You are quoting factory minimums. However, they are not factory norms for the LT1.

20psi@800rpm is "normal". He should be pushing around 40psi@1500rpm. Stock pressure peaks at around 50-55psi. If he has a high pressure spring in his oil pump now, depending on the oil type used and his clearances....he might run around 50psi@1500rpm.

I have a high pressure spring in mine and I'm 50psi@2000rpm. Cold startup my pressure is 70+psi. I have no oil leaks either.

However, I did develop a rear main seal leak after my rebuild. If you manhandle the rear main seal installing it, it can leak...and that is what mine did. I recently replaced it when I changed out my clutch disk and it's all good now.

I don't think your rear main leak is related to your oil pressure. Excessive crankcase pressure could cause an issue, but I can't speak to that issue well(never had issues with it).

 

Ahhh, he beat me to it, but is right on the money.

 

Many seals, especially double lip seals, can be folded over when installed. I don't know which the rear is but the point made before is install errors are common. I always lift up the outter lip to view inside to look at the inner lip before I'm done with the seals I've installed.

Very much doubt your problem is related to oil pressure issues. However, loss of crankcase vacuum can be your problem. A healthy engine always has a slight vacuum in the crankcase. Without a working PCV, and engine would leak from several areas. The vacuum level can be tested with a manometer. The electronic type are much better than the old water type.

 

I think the first thing to do is be certain it's the rear main seal that is actually leaking. The oil could be leaking at the back of the intake manifold and dripping down, making it look like the rear main is leaking.

If the rear main is leaking I second the opinion that it's likely due to a seal either damaged as received or during installation.

While possible, I think it unlikely that high crancase pressure would lead to a leaking rear main, especially if other, less robust, seals aren't.

If it does turn out to be the rear main seal, look very closely at the crankshaft seal surface for any nicks or scratches...these can tear up a seal on installation. Finally, and I don't mean to insult you, be sure the seal is positioned correctly on installation....double lip seals only go one way.

Good luck!

 

Didn't read all the posts. I have heard the intake rear seal is a tricky one to get right. Many have tried two, three or more to get it sealed.

 

thanks for all the responses guys, i know for sure my intake is not leaking as it felt dry and clean back there. car is going to the shop this week to have it further looked at and fixed