Thread: Intake manfold oil leak

Tweet

Hi everyone,
I got about 400 miles on the new ZZ4 now, and after a nice cruise today I smelled that distinct odor of burning oil. I crawled under the car and saw some oil dripping off the starter and conveniently right onto my exhause pipe. I tracked the leak up to where the block, head, and intake meet...Of course in a spot where I cannot see, but only feel the oil with my hand. GM uses grey sealant there. My question is, are there any good tech articles out there on how to change the gaskets and sealant? Ive never done it before so any good articles, tips, advise would be much appreciated.
Thanks in advance.

Are you running a PCV and breather?

Originally Posted by Stu Cool

Are you running a PCV and breather?

Good point. Also, it might be your oil pressure sending unit.

Yes, Im running a pcv on driver side front, and breather on passenber side rear. Oil sender is just above filter, no leaks there.

Can high oil pressure cause the seal to blow out? I have 25 psi at idle and 55 at 3000 rpm, sounds high but I think thats normal for the ZZ4.

Originally Posted by 63BoxNova

Can high oil pressure cause the seal to blow out?

No. Blow by will cause seals and gaskets to blow out.

Ive heard the term blow by before , what exactly is it? Im sure its something with the rings wearing. Its a new motor, is it possible that I could have blow by? Also, just thought Id mention it, but the grommets in the valve covers holding the PCV valve and oil cap also spray a little oil from around the edges too.

Blow by is pressure created in the crank case by compression sneaking past the rings. In a brand new motor where the rings have not seated completely yet, this could happen and should go away as the motor breaks in. That said, the PCV and the breather should take care of that problem. Make sure the PCV is pulling vacuum when the motor is running. The other thing to check for a leak in that area is the distributor gasket. Make sure it has a good seal and is seating down tight. I have seen distrobutors that sit just slightly too tall and need an extra gasket to seal. Can you get an inspection mirror back in there? Maybe clean it up was well as possible, then run it again and get back there with the mirror before you stick your fingers back there. That way the path of the oil will not be disturbed. Would be good to know where it is coming from for sure before tearing it apart.

One more thing, if this is a new crate motor would there be a warranty?

Pat

Thanks Stu. Tomorrow I'll clean it up and stick my inspection mirror back there. Its a tight squeeze between the engine and firewall, so I hope I can get a good view. Ill check the distributor gasket too, I hope its that simple.

By the way, I replaced the grommets on the valve covers today and that worked to stop the oil spray. That little problem is solved. Also checked PCV and it pulls vacuum.

The motor is under warranty, but Id hate to bring it to a shop to have the leak fixed. Im the guy who would rather learn and do it himself, its a pride thing. But I guess sometimes you have to swallow your pride.

I had a similar issue when i first fired mine up for break in......just use RTV black silicone inplace of the cork rail gaskets, 1/4" bead slightly overlapping the intake gasket. drop the intake on and torque it down tight. I didnt use enough near where the head gasket met the end rail and I had a leak, puked oil all over my ceramic coated exhaust.....was'nt nice.