Cadillac: over heating, head gasket leak, seville sts

Question
I have a 1996 seville sts with a 4.6 eng.I put a new rad in it a new thermostat a new cap.at idle or low rpm's it is fine,but at higher rpm'S IT BLOWS THE WATER OUT OF THE OVERFLOW TANK.DO YOU HAVE ANY IDEA HOW TO FIX THE PROBLEM

Answer
Did you install a NEW radiator or just have yours CLEANED, RODDED and FLUSHED by a radiator shop ?.

Did you TEST the new THERMOSTAT BEFORE you installed it ?. Most likely NOT.

Did you check the cooling fan for proper operation whether it being a standard clutch fan or an electric fan ?.

Have you had the cooling system PRESSURE TESTED for an internal head gasket leak ?. Most likely NOT.

If you have a small braek in a head gasket between the cooling chambers and the combustion chamber(s) Combustion pressure will buildup within the cooling chambers, Thus causing cooling flow to stop and expulsion of the coolant results.


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