Cracked Manifolds

Tahoe933 · June 7, 2001

A friend of mine has an 88 GMC with a 454. He can't get it inspected due to cracks in the exhaust manifolds.

Anyone hear of these troubles before?

Can they be fixed or should he just replace?

What causes it?

Mike

June 8, 2001

I have heard of exhaust manifolds cracking, but it has always been something extreme, like racing on a cold day or putting water on a hot manifold.

What is much more common and harder to diagnose by the high school drop-out that works at the inspection place is blown gaskets. The exhaust manifold to head gasket could have deteriorated or the exhaust manifold to pipe(donut) gasket has blown out.

When the motor is cold, fire it up and run your hand along the exhaust manifold. You should be able to feel the leaks.

76BBSub · June 8, 2001

Friz is right...

The only thing I'll add is that if his FI is off somehow, maybe a bad O2 sensor or the timing is WAY off, either of those things can cause excessive exhaust gas temps that can damage manifolds without showing excessive temps on the coolant temp gauge.

Jeff

Eric Bryant · January 13, 2002

I can't say anything about this specific vehicle, but some GMs have had problems with cracked exhaust manifolds under heavy-duty use (towing, off-roading, etc.). I had a manifold replaced on my Impala back in its stock days - it's a fairly common problem with the '91-up B-bodies.

Just look at it as a good excuse to install headers

lsu-sec · January 17, 2002

I know someone who had a GMC based motorhome with a 454. It had a cracked exhaust manifold.

January 18, 2002

I know someone who had a GMC based motorhome with a 454. It had a cracked exhaust manifold.

That is a problem with motorhomes. However, the very few motorhomes that I have looked at all had headers on them. They're still called exhaust manifolds, but they all looked like tubular headers to me.

(Gas engines only)