I had a new short block put in my 97 GMC Sierra.

ANONYMOUS

MEMBER
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?

Friday, November 2nd, 2012 AT 4:49 AM

3 Replies

SATURNTECH9

MECHANIC
30,870 POSTS

Is it a constant missfire on those two cylinders?

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Friday, November 2nd, 2012 AT 5:15 AM

BONECOLLECTOR2012

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14 POSTS

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.

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Saturday, November 3rd, 2012 AT 1:12 PM

SATURNTECH9

MECHANIC
30,870 POSTS

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;

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

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Monday, November 5th, 2012 AT 3:00 AM

I had a new short block put in my 97 GMC Sierra.

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