08WhiteC6

Hello all… New crossover from the Mustang world..

I purchased a 2008 C6 back in July. The car had 29K miles. It had a bad oil leak when I purchased it and took it to the Chevy house to have it looked at. First they changed the oil pan gasket, took it home and still leaked. Took it back, they changed the gasket again, but then realized the leak was coming from the rear main seal. So they replaced it and fixed the leak.

All has been fine until last week. Took it in for the rear end clunking / popping and they performed the diff oil TSB. Picked it up and half way home I started smelling burning oil. Let it sit over night and had a nice 6” diameter puddle below the car. Check the oil and it was a little low so I added a ˝ qt. On my way back to the dealership, I was experiencing oil pressure as high as 74 when the rpms reached about 4500-5000. Never notice it that high before. Oil pressure and oil temp are two of the three main parameters I always keep an eye on.

Anyway, dealership just called and said the rear seal appears the be leaking again and they are concerned about the high oil pressure causing the leak. They are waiting to hear back from Chevy engineers before doing any work, although they think it has something to do with a pressure relief valve in the oil pump. I have read about this before, but everything I read was about the valve getting stuck and having no or low oil pressure, not high oil pressure.

So,,,,,,, my question now that I wrote a book… What could cause the high oil pressure????

Thanks
Jeremie

Gearhead Jim

If the pressure is normal at low rpm but gets too high at higher rpm, I'd be wondering about the relief valve.

I suppose it could have a spun bearing (can a LS3 do that?) but much less likely.

Or simply a bad gage/sender, and the oil leak is a coincidence.

The experts should be here soon...

AORoads

well I'm not the expert jim's mentioning, but if you ask me, something's wrong with that dealership. to go out leaking, and high pressure next means someone's not minding the work they're doing and just fixing things. used to be called throwing parts at it.

got another qualified dealer and tech nearby?

Gearhead Jim

Bill has a good point, the experts are not at that dealership.

08WhiteC6

Have many to choose from, however, this one provides free loaners. I'll see what they come back with and go from there.

If any experts have something to add about the high OP, please post away.

Thanks,
Jeremie

roscoe118

Not an expert by any means, but just went through a similar, but opposite problem with our '08. The oil pressure was too low IMO at idle, when hot.

As I understand it the LS3 has a relief valve in the oil filter, and in the pump itself. My pressure was reading ~8 - 9 PSI, when the oil temperature got to 200+ degrees. Not uncommon in these Texas summers, especially this one... It would go to normal ~40+ PSI when you accelerated and the RPM's went up. Believe it, or not, 8 - 9 PSI is above the minimum GM spec of 6 PSI (I believe)...

I read somewhere on here where either of these valves could stick open when hot. I replaced the filter with no luck, so I talked to a local Chevy dealer, and got them to replace the pump under the 5/100 warranty. The idle pressure has been "normal" (~28 - 32 PSI) ever since.

Perhaps one of yours is stuck closed??? Easy and cheap to try the filter. If that doesn't fix it, perhaps you can convince a dealer to replace the pump, if they haven't fixed it already.

Bill Dearborn

There are several places where they can leak oil. The pan gasket, the front cover seal, the main bearing cross bolts and the rear seal. If the front cover seal is leaking you can get oil all over the bottom of the car with oil dripping from the oil filter, etc. Same goes for one of the cross bolts. These leaks seem to be much worse once the rpms reach the 5K level. You can run the car for a long time at lower rpms and get little to no oil leaking and then just let it rip for a few minutes above 5K and you start smelling oil and leaving puddles of oil on the ground. Been there experienced the mess, didn't get a T Shirt and it took from October through May to finally solve the problem. On my LS7 they replaced the oil cooler line, the pan gasket and finally the front cover seal which finally stopped the leak.


Bill