fst100

iTrader: (5)

late last year I had a stall converter swapped out done by my mechanic and he had told me that the rear main seal was leaking and I had him replace it. fast forward a few weeks and while pulling out of my garage I noticed fresh oil spots on the ground (layed the area with cardboard to prevent staining the concrete floor). I tried looking for where the leak was coming from but wiping down the oil pan and trans pan from the grime and oil splatter makes it difficult to narrow down after driving it a few more times and putting it on jackstands again.

IF the rear main seal is fixed, and I had already replaced my oil pressure sending unit, is there any other place(s) that would cause a slow oil leak?

matt02ws.6

I had an oil leak that I fixed where I originally thought was coming from the rear main but it was actually coming from the cover that the rear main sits in. There is a valley in the cover that sends oil for the lifters from one side of the engine to the other and since that is pressurized it is more prone to leakage. After putting over 25,000 miles on the car since replacing the cover seal, it is still totally dry.

ddnspider

iTrader: (26)

I had something similar and it was the valley cover gasket.

fst100

iTrader: (5)

Matt and ddnspider, are you both saying the same thing or 2 separate areas? lol

ddnspider

iTrader: (26)

No. He is saying the leak is from the rear cover itself which has a gasket. I am saying my leak is from the valley cover under the intake manifold.

LS_ELKO41

iTrader: (6)

My car is currently leaking as well near the oil filter so have been researching. It could also be the oil bypass adapter near the filter or the oil pan leaking. I am replacing my entire rear main cover which includes the rear main seal and gasket for the cover as well as my oil pan gasket. Thinking about changing out to an LS6 valley cover now since I have an 02 and won't have to clearance the block along with a new seal there too.

fst100

iTrader: (5)

gotcha. when I replaced my OPSU I checked around the valley cover lid and didn't see any leaks around there as well as around the OPSU. it was dry.

I would assume if the rear cover gasket was leaking my mechanic would of suggested changing that gasket instead of the rear main seal itself.

I had came across some older posts about the oil bypass adapter leaking but I haven't done an in-depth search on what's all involved.

LS_ELKO41

iTrader: (6)

I think the bypass adapter is just 2 10mm bolts and a small gasket that is pretty cheap iirc.

bammax

Mechanics that work on old engines don't always know that the rear cover is removable. If he used a seal puller and yanked the main seal the old fashioned way it could have caused the cover gasket to fail. If he pulled the cover and knocked the seal out on the bench then he already replaced the cover gasket when he put it back together.

matt02ws.6

I found this picture online and this explains is exactly where mine was leaking and the route it trickled down from.

bammax

That's what you call a diagnostic nightmare. Most would change the pan gasket and wonder why it's still leaking.

LS1121

iTrader: (17)

When I replaced my rear main seal I bought the entire setup, he did the oil pan gasket at the same time, no more issues.

https://www.ebay.com/itm/Chevy-GMC-B...!-1:rk:15:pf:0

LS_ELKO41

iTrader: (6)

This is the route I am taking.

sjsingle1

iTrader: (1)

That circled item in the pic is the O ring on the cam sensor....common leak point

LilJayV10

iTrader: (39)

Some LS engines had a block porosity issue on the rear of the block. I think GM actually has a TSB on it
their fix is to RTV it IIRC. also I was not aware of the cam sensor leaking in the rear. Makes sense though