Mechanics

GMC SIERRA COMPRESSION PROBLEM

1997 GMC Sierra • 150 miles

I had a new short block put in my 97 GMC Sierra and I now have a misfire in cylinders 3 and 5. I have new plugs, wires, and complete distributor assembly. The reason for the new short block is the crank broke on the old one. Could I need new heads?
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Guest
November 2, 2012.



Is it a constant missfire on those two cylinders?

Saturntech9
Nov 2, 2012.
Yes, it almost sounds like an exhaust leak. The oil pressure gauge bottoms out when you stop too. When the shop reassembled it they just bolted the top side back on. They didn't even look at the valvetrain. I haven't pulled the valve cover off yet and looked at it.

Tiny
Bonecollector2012
Nov 3, 2012.
I would do a compression test they should have done a valve job while the heads are off. It is really hard to say. If you had bad head gaskets, you would have other issues like overheating or oil in the coolant. Since there are so many possibilities I am giving you a walk through diagnostic for your situation. Just use the link below to get to it;

http://www.2carpros.com/articles/engine-misfires-or-runs-rough

Saturntech9
Nov 5, 2012.