2004 GMC Sierra Car keeps overheating

2004 GMC SIERRA
57,000 MILES • V8 • 4WD • AUTOMATIC
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TOBYSMOM2
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Recently my truck has been overheating. I replaced the thermostat and still overheated. So I replaced the water pump, still overheating. I disconnected the upper radiator hose and flushed water from in the upper radiator until it was clear in the upper radiator hose. It's still over heating! Any ideas?
Mar 26, 2008 at 11:21 PM
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RASMATAZ
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Have it block and pressure tested-do the block first to pinpoint a combustion leaking into the cooling system or a gas analyzer to sniff for hydrocarbons at the radiator fill neck.

Pressure test: do not do a pressure test if there's leakage at the headgasket this might cause coolant into the cylinders and lock it up or bend a connecting rod if cranked thereafter. The headgasket should be repaired before doing the pressure test.

If the block and pressure test passes check the following: Thermostat,Pressure test the Rad. cap,Clogged radiator,Fan clutch,Radiator electrical fan,collaspe hoses,water pump.
Mar 27, 2008 at 7:15 AM