I have a 1988 350 TPI engine that has 55,000miles on it . It has had head work done by the previous owner, who knows why and now it has what sounds like piston slap when driving, accelerating, but quiet when warm and idling or not under load. It has no compression on #3 cylinder, but no signs of coolant seepage, oil or any sign of a head leak . I am ready to pull the head and see what is really wrong, but before I do that, any ideas on other tests or possible problems?

I need this engine for my project car. I have recently acquired a 1988 Iroc Convertible with 36,000miles, stored winters and never seen rain. One problem, no engine! The previous owner went too far with high performance and blew the motor, and pulled it. Now, I am trying to restore it to its original configuration.

Thanks in advance for any assistance!

Marty

 

Sounds like a burned exhaust valve...

Turn the engine to #3 firing, hook an air chuck up to the cylinder and pressurize it, and see where the compression is going. It should be fairly obvious: it can go into the crankcase (pressure coming out the dipstick), cooling system (pressure in the radiator), intake, or exhaust.

 

That's the beauty of a cylinder leakage test. Not only do you know the condition of the cylinder, but you get a better idea of what's wrong.

 

disconnect the rocker arms and test the compression again. Mine did the same thing yours is when i broke a valve springs.

 

Thank you all for your assistance. Running this test has made me discover that the original compression test was incorrect. When I pressurize cylinder 3, it comes out cylinder 5. If I put the air into 3 and the compression tester on 5, it pressurizes! I can now assume that I have a blown head gasket between 3 & 5.

I am going to pull the engine first and then change the gaskets before putting it into the convertible. I am also considering have the heads ported and polished first.