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This is from my 2001 Silverado LM7 that I recently purchased.
Pulled it apart and found the Valley cover was what was leaking.
Luckily my knock sensors came out with no problems.
I changed;knock sensor,cam sensor,oil pressure sensor,valley gasket,valve cover gaskets,intake gasket,PCV.
Seams to have fixed the leak.
Intake was a mess on the inside,pressured washed it at the local car wash.
Will be adding a catch can.
I believe the oil leak is fixed. I only add a quart about every 2000 miles now. I was adding a quart every 500 miles. I don't think it was the cam position sensor, or the oil pressure sensor though. Once I got the valley cover off, I could see a lot of oil along the rear section. The way it's designed, you won't see that portion of the valley cover leaking. It will just look like the cam sensor or oil press sensor leaking.
Changing the valley cover seal really should be an easy task. I had hell with the knock sensors. That's why it was difficult for me. If you know you have a leak in that area, I would recommend replacing the valley cover seal while you have the intake off. The seal is cheap, and it *normally* doesn't take long to replace. The cam sensor is also really easy to replace, so you might as well replace it too while you're in there.
Thanks ... I think that's my next step. I crawled under it over the weekend and for the life of me couldn't tell where the leak was coming from. I had my UV glasses and the drop seems to be coming from above the starter but also at the center of the block and the bell housing. I'm adding about a quart per week which is about 500 miles, which is where you were.
Yep, mine was leaking/dripping from the same spots. The valley cover gasket will let it go down both sides of the block. That's why it's hard to pin-point the source. Just tear into it and replace everything at once. That way, you won't have to go back in there again.
You know the reason the dye could be getting up into the intake runners is due to reversion. One of the members suggested this as reason why my intake was getting oil residue up into the runners. I'm venting to atmosphere so no PCV here but I'll eventually be making the move over to a vacuum pump and breather can set up. I never did clean the damn intake after replacing the heads and I should have. I'll get around to it one of these days when business permits.
I agree with the reversion idea. One of these days, I plan to fix this problem by adding a positive pressure source to the intake. I'm thinking 8-12psi should do it.
