Cadillac Jim Posted June 6, 2007 Report Share Posted June 6, 2007 Occasionally some mechanic pulls down a Northstar that is overheating because of less than 50% anitifreeze or a slipping water pump belt or leaves covering the raidiator or whatever, then drops one of the cams and wants the owner to pay for it all. The things to look for in a head gasket diagnosis are: Coolant not changed for a period exceeding the warnings (5 years for red, 2 years for green) Another few months to a year without incident, Gradually increasing loss of coolant in freeway driving without discernible leaks, Temperature spikes about 30 seconds after topping a hill or passing a truck on a 2-lane road, Gradually increasing sensitivity to overheating after topping a hill or whatever, and, finally, Failing a pressure test and testing positive for combustion products in the coolant. If it's overheating at traffic lights while stopped, it probably isn't a head gasket. If it's leaking coolant, it probably isn't a head gasket. Any good radiator shop or general purpose mechanic can test for combustion products in the coolant and rule out head leakage in a few minutes. If it's a possibility, that's a good idea because it either ends the diagnosis process or gets you into the overheating checklist in the FSM. Never pull down an engine unless the coolant tests positive for combustion products. If it doesn't, then the head gaskets are just fine. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
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