overheat problem on 2004 Buick Park Avenue

HELP! Fast and excessive heating > 225. Thermostat & hose replaced (top hose was split but themostat didn't appear that bad)....no detectible leaks now. heATER THrOWS HEAT ok AND WATER IN RADIATOR HEATS QUICKLY....so it seems like water is circulating through the engine. While driving, temp gets to > 225 quickly and varies several degrees for no apparent reason. After driving a while the preignition begins (engine rattling) and engine dies. I can't see where or if water is getting into the oil (bad head gasket?)..it seems ok but need positive check. What else could cause this? thanks RT

by in Fort Worth, TX on August 04, 2010
1 answer
ANSWER by , August 05, 2010
Could be the water pump but head gaskets will definitely do that as well and water don't always have to mix with the oil to have a bad head gasket do a compression test that'll tell it all.