2006 Avalanche Overheating ISSUE!
2006 Avalanche, 5.3. Replaced Water pump, Thermostat, Engine Coolant
Temp. Sensor, properly filled with correct fluid, NO WATER in oil. (Typically
rules out head gasket). Hoses appear to be fine, both are warm to hot, not
collapsed. There appears to be flow, when heated. Runs fine at idle for up to
25 or 30 minutes, after driving a few miles, Temp will jump from 165-170, to
redline in mere seconds!!!
Clarifications: Just removed the NEW Thermostat, dropped it into boiling water, after about 20 seconds it started to open. I let it fully open, then using pliers, I pulled it out and watched it slowly close. T-Stat not the problem. Flushed entire system this morning. Pulled all hoses and checked for collapse and/or any damage. They all look great, and system had no blockage or debris inside it as I was flushing. I am completely stumped, unless the NEW Coolant Temp. Sensor is bad. I have removed that, and taking it back for a replacement. We'll see if that is the issue. Keep your fingers crossed.