Started with a leaky oil pan gasket. Changed upper and lower. Then timing cover and seal up front. Did those twice because the shop in Utah did them wrong. Then rear main. Then valve cover gaskets and that gasket on top under the intake. All was great. Made it two days. Just started dripping. Smells like it's that gasket on top again. Dripping back onto the manifold again. Then dripping off the back of the oil pan. That was changed 4 days ago. In the last month I'm over 2k into gasket changes. I've never had so much trouble keeping an engine oil tight in my life. This is crazy. I even went to Chevrolet to have them all done. Simple gasket swaps. Am I an anomaly or is this common?

 

Never heard of such grief...you truly have the patience of a saint. I probably would have deep six that car a long time ago as don't have the time or money. Here is wishing you some good luck....finally. Hope some other guys will comment on your problems as I am interested too.

 

Too bad you're having so many problems getting the oil leaks stopped. I can see where it would not only be costly, but very frustrating.

 

Hang in there. Seems like you've had more than your share of leaks. The rear end and oil pan leaks are pretty common. I've been lucky. I'm on my 3rd C5 and only had the leaky butt on an 02.

 

Sorry to hear of all your problems.
I've had 4 C5s, none have leaked any oil.....so far.
My 02 was leaking antifreeze but I'd be damned if I could find the source of the leak. Somehow, it seems to have solved itself as I no longer see small puddles of antifreeze.

 

I feel your pain. Did you have the leak after changing the oil pan gaskets?

My C5 had the oil pan gaskets changed three times and the rear main seal once by the first owner. The first time a Chevrolet Dealer did the work with the rear main replaced(still leaked). The second and third times she had it done at a local repair shop(still leaked).

When I purchased the car I removed the engine and began looking for the cause. I tore down the motor checking carefully looking for the cause. The oil leak was coming from the upper oil pan gasket on both right and left rear corners and dripping onto the exhaust.

I did not see any problems with the upper gasket at all. It looked good as a new gasket.

I then thought about the surface of the sealing side of the upper pan.
I took a straight edge and checked the flatness of the rear of the upper pan. I also checked the sealing surface of the block and it was flat and true.

The straight edge would hit in the center of the back section of the upper pan and rock back and forth showing that the surface was warped very badly.

I took the pan to my machine shop and they surfaced the upper sealing surface. The machinist noted that the surface was way out of flatness and no way could it have been sealing properly.

I rebuilt the engine and reinstalled the rear oil pan and now two years later no leaks whatsoever. The warped rear sealing surface of the pan was the problem all along. I do not know how this surface could have been warped, it definitely was the problem.

I would say that this would be easy to over look this problem and three times it was for the first owner.

I hope that you can get it fixed. I hated the mess on the garage floor and the smell of burning oil every time I drove the car.

I am not saying that this is your problem but it is something that should be checked before just changing another gasket.

 

I've had 4 C-5s and two other LS engines without any leaks.
In fact that is one f the reasons I love the LS engines after having numerous small block cars and a couple of Northstars.

Is it possible that the harmonic balancers is causing the leaks?

 

New harmonic balancer too.

 

mine is bone dry !!! having them run so hot does not help, I like mine running at 192 !!!!!

 

Have you checked the PCV system. If not working it can cause leaks. Good Luck

 

Buddy I feel your pain!!!

While changing my PS rack it took the opportunity to fix all the leaks you mentioned. Thought I was good but then noticed oil on my driveway...the only part I didn't change was the rear main seal. But I'm not going to do it until next spring...that being said, you shouldn't have these re-occur. Either the car needs to sit longer to make sure the seals have settled or it could be improper install, or even bad gaskets. Hope you can sort it out!!!

 

Were all the fasteners torqued to specs & proper sequence?

Also did you check to see if your oil pressure switch is causing the leak at back of the manifold?

 

I was talking to a friend who is rebuilding a C3 and he mentioned to check the oil filter adapter gasket. I have a similar issue, oil on the exhaust, dripping from the filter area. Checked the topside and the oil pressure sending unit was good. PCV hoses were all gone, replaced but still leaking.

I think the adapters are normally on there with two bolts if we have them on C5s. Anyone ever do one of these?

 

I would definitely check this also. If your PCV system is not venting the crank case, it will pressurize and push oil past whatever gaskets it can.

 

Yes. And yes.

 

That is likely it. Guess I need to change it. This would make sense that it only leaks when I get on it too. If I gently cruise there is no leak.

 

I feel your pain my friend. I am swapping out oil pans on my 02. Caught a rock and punched a hole in my pan right behind the leaf spring. I was leaking oil before that so I'm going to change out all gaskets and seals top to bottom. Adding a oil pressure sensor relocation kit also.

 

Wish I had thought to do the relocation kit at the time.

 

Holy crap. I think it worked. New PCV setup. Drove it hard. For 2 days. So far nothing. Amazing.

 

I’m stunned that the problem was a PCV valve. At least it’s clean inside. Can you tell I change oil?