Ok guys/gals I have a question for ya? I have been having issues with my T/A leaking oil from the rear and I can't tell if it's the rear main seal or the pan gasket at the rear. I replaced the pan gasket about a year ago and the car only get's about 100 miles a year so it's pratically brand new. When I took the pan off (last time) the rear main looked pretty dry, but even now I am seeing oil dripping off the inspection plate on my T56. I will get about 4-5 drops on the ground after I park her and can't figure out if it's the pan or the rear main. The oil seems to look like it's coming from the pan seal as droplets are on the rear pan bolts and front of the inspection plate, but is there a way to tell if it's the main or the pan gasket?

FWIW - I am 100% positive it is not the intake or oil press sending until (no oil back there). Also, I don't have the one piece rear any more as my builder switched to the two piece design back in 99' (what he prefered) with an adaptor - see below pic:

Oilpumppickupweldedtopump.jpg?t=1239029772

Any ways to definitively check and rule one or the other out - oil in bell housing, etc????

Thanks and I appreciate your advise.

 

Any advise guys???

 

I've had problems with both the pan front seal and the rear main seal. Symptoms and observations the same as you have identified (some drops of oil off the inspection cover). My app... 97ss 383 D1 M6 Moser_12 - 15psi.

The LT1 crankcase evacuation system can be the problem. Check the PCV valve and suction if NA aplication. I actually have blown out the front pan seal due to blow-by and crankcase excessive pressure (note to self... always drop the pan when removing the front cover - no hammering/ prying!). Also, my opinion is a GM brand rear seal is better than the Felpro. Also, alignment of the rear seal housing can be off. Concentricity can be off, and be a cause of reduced gap sealing. I pile some Permatex grey in the corners of the pan gasket @ front and rear mains.

I have engineered my own fix with an externally mounted crank driven GZMS vac pump. No leaks now. (Pix on photobucket.com under my ID). Quite an increase in cylinder pressure, and, more fun.

I have never had my clutch (spec_3) contaminated by oil from the inspection plate.
Leaks... we all have them.
HTH B.

 

100 miles a year, wow thats not a whole lot.
anyway when i recently had my engine done it leaked in the rear like you have described, but i couldn't find a definite spot it was leaking from, until i took the inspection cover off and since i have a small torque converter i saw one of the plugs(i think it was a freeze plugs) that was seeping a tiny bit of oil. not a lot just enough over time to leave a few drips on the ground. left it go and about 1500 miles later it finally sealed up.

 

Thanks for the input, I don't think it's the PCV system as I recently replaced my PCV valve and I have a breather as well on my VC (pass side) that should help keep that at bay. I replaced the timing cover seals this weekend to fix the front leaks (WP, Opti and Crank) but the timing cover gasket is bone dry and was sealed up good when they put it back on there during my cam swap 2 months ago. WP seal was put in wrong giving me a leak on the front, but no biggie and easy to fix this weekend. The thing is the rear is really a pain, and I can't tell where it's coming from. I had a clutch go out on me last year and when I pulled the tranny the inside of the bellhousing had some caked greese/oil on the inside but it looked to be my oil pan seal as the crank seal looked to have no oil on it at all. I tightened up the rear bolts on the OP again this weekend (torqued em down real good as I have the felpro gasket with a steel core so not worried about over tightening) as the rears seemed to be not as tight as I'd like. Guess I'll clean it up real good this weekend with some simple green and see if I can spot if from the pan seal or not. Would a pan seal leaking spit oil inside the bellhousing as well and when pulling the inspection plate off is there any tell tale signs to look for if it is the main?

 

Thanks, but not sure it that could be it, as the concentration was from the pan seal location/rear main. No oil above that area.

 

yeah just thought i'd throw that out there to stimulate your brain the way it was leaking down the back of the motor it went to the corner stud on the pan and made it look like the pan gasket was leaking.

 

OK, awesome news!!!!!! Fixed the leak this weekend. Pulled the pan and did the rear main (pretty easy on a 2 piece - once you get the pan off). Used some "The Right Stuff" to seal up the 4 corners of the pan and both side of the rear and front lips of the pan. Let her run for 30 mins on the lift and then drove it for a few miles and let it run for 30 more mins and so far ZERO leaks!!!! I am so glad this is over (for now) as I have been chasing this rear oil leak for years. Also parked her with some cardboard underneath for a couple of days and checked yesterday to find ZERO drips or runs. Thank GOD and thanks for all your help guys.