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Engine operating temp under extreme conditions

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Hello all


i have a question about engine cooling on these trucks... might need a new radiator. idk.


2004 sierra 1500 4x4 5.3


scenario 1- sitting in the shade with the AC on during 103 weather.... engine reached 230. had to shut the AC off and drive the truck to cool it back down.


scenario 2- tuck pulling a 5,000lb trailer up a hill at 3,500 rmps 60mph.... truck reached 230, then cooled back down once the hill was taken and started cursing again


scenario 3- going 90 mph at 3000 rpms with the AC on and 90+ degree heat outside..... truck reached 230, shut off ac and slowed down to cool engine.


someone USED to make a high flow racing thermostat housing for these engines... but i think the rona & CA laws killed them....

but does this sound like a radiator issue?

water pump works well. only 1 year old.

fan clutch is good.


how can i make this engine stay at 180. period. ???





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so you might want to replace your thermostat, and since you will need to drain the coolant to do so, go ahead and flush your Hvac w/ a garden hose on light water, putting the water through the return, basically reverse the way it would normally flow. Then Also flush your radiator with water.  Put everything back together, and be sure to bleed the system very good.  Dont lose patients on the bleeding procedure.  

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Iron block? If so feel the bottom of the radiator.. and check that it is not solid with rust from the engine collecting there..if it is clogged it will be cooler than the top half of the radiator.. then replace it.

Edited by PPK
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