cylinder heads

[sazamar]

I have a 1991 GMC suburban with a blown head gasket between the last to cylinders on the passanger side. My machanic there are cracks in the middle two cylinders which make the head unusable. How does one tell if these are surface cracks and if so, can the head still be used.

Also, can a head from an '83 6.2 engine be used on a '91 6.2 engine?

Thankyou,

Dick Sazama

[john8662]

An image of what you're seeing (or the mechanic) would be good.

Cracks accross the surface of the head make the head unusable, but the small cracks that start between an intake and exhaust valve are usually not a problem and are repairable with a sleeve kit for peace of mind.

Usually leaking between two cylinders side-by-side indicates a blown head gasket.

The 91 heads are different from the '83 heads. If you swapped them both out and had a matching pair, you could put the '83 heads on.

It's usually a good idea to replace both head gaskets if you find one blown.

J

[More Power]

The 83 heads will also require a set of injector fuel lines produced during the 1982-89 model years. GM changed the injector angles in the cyl heads in about 1990 or 91, which changed the length of the injector fuel lines. The injectors were angled more upright to allow more room for the side-mounted turbocharger they eventually began using in 1992.

To save money, some have bent the lines to fit, but it's not a good idea for both appearance and functionality.

Jim