I have a 1996 Pontiac Bonneville started to run terrible and finally we discovered hydro lock. We stripped the top half of the engine and replaced all the top half gaskets. Replaced the EGR valve, replaced the Plenum, new PVC valve and fixed all the vacuum lines. We have new plugs and wires.

After replacing all these the motor runs well for about 15 minutes until the temperature gets high, then I hear a click sound and a horrible noise starts. The sound is similar to a screaming slipping belt. When I take off the oil cap, I hear/feel suction and the noise disappears. This happens only when the car warms up, if it's cold, this does not happen.

Does anyone have a solution or idea why or how to fix this. Please help me! I have dumped $750 into the car and a mechanic can't even tell me what the problem is without tearing the car apart again for another $700. Thank you!

I have a 1996 Pontiac Bonneville with the same problem with a melting intake manifold due to the plastic gasket. After replacing the intake manifold the motor runs well for about 15 minutes until the temperature gets high, then I hear a click sound and a horrible noise starts. The sound is similar to a screaming slipping belt. When I take off the oil cap, I hear/feel suction and the noise disappears. This happens only when the car warms up, if it's cold, this does not happen. Does anyone have a solution or idea why or how to fix this. Please help me! Thank you!

P. S. There is a new PVC valve and sensor