Eric_Stang13

Hey guys, im decently new to these forums but been working on my cars for several years now. Iv'e ran into a recurring problem...

I have a decently built 347 with a KB. On my street tune(10+/-psi) I can drive all day never burning any oil or have any kind smoking from burning oil. But if I switch out pullies and tune to my track tune(19.5psi) I can maybe complete 3 maybe 4 1/4 passes and I begin getting oil(i believe) out of my rear main seal?

I'm getting rather frustrated with this problem after replacing the seal at least 4 times now hopeing I messed something up the past times.

Thank you in advance for your time, if you need any more details on my vehicle just ask.

nightmare90gt

it can also be your oil pan gasket, what about your pcv valve is it new or working

Eric_Stang13

I replaced the oil pan gasket in between replacing the rear main the 2nd and 3rd time. pcv valve is new with the motor with roughly 12k miles on entire setup

.boB

Every oil leak on a SBF shows up on the front of the block plate. They all look like a RMS leak, but rarely are. The new one piece seals are so good, that they rarely leak. So start looking in other places. Could even be the front seal around the balancer. Use a dye kit, or a smoke machine.

But the real problem is not the seal. You don't get a leak unless you up the boost. You're most likely pressurizing crank case, and blowing oil past a perfectly good seal. You need to improve your venting system. With the added boost, your stock style PCV system can't handle the air volume.

Connect the oil pan to a valve cover with a -10 line. Then use a PCV system that connects to the header collecter. That's a simple passive system that should solve your problem.

A vacuum pump is a great idea. But it can be expensive, and doesn'ty always work. I tried using one on my car. And for the street and drag strip it worked just fine. But on the road course it would suck the oil out and spewed it out the top of the collection tank. What a mess.

jsaleen90

I agree with the above statement that it is probably not the RMS and is due to the extra boost pressure that the PCV system cannot handle the pressure. Remember your adding boost to a car that was never intended to have boost so some of the standard equipment may be inadequate to handle higher levels of boost.