I recently replaced thermostat and ECT sensor.

Bravada temp fluctuates while driving. It is anywhere from 210-230. After driving I shut the car off and let it sit a few minutes and turn the car back on and the truck is hotter than it was before approaching the 260degree mark. It cools down eventually to about 220-230 when I drive. If i shut the car off while its hot 220 or up it and leave it, it will overflow and bubble out of the radiator cap.

Fan is on
Radiator full

Is my radiator shot?
Should I try a flush?

I'm lost.

 

Cooling system flush will help if it's restricted. If ethylene glycol, (green coolant) is added to the Dexcool, (orange) coolant, it will cause the cooling system to sludge up and the engine will overheat. The fan clutch may not be engaging or there could be debris in front of the radiator and or AC condenser.

To flush the cooling system: pull both hoses off the heater core, along with the upper and lower radiator hoses from the engine. Flush both directions in the heater hoses until water comes out of the water pump clear. Then flush the heater core in both directions. Then flush both ways through the radiator. Connect all the hoses and fill her up 50/50 water/Dexcool & burp it...... done.

 

+1^ Was it doing this before termostat change? Also temp always goes up after shut-down. Water pump stops engine block still hot.

 

Here's why I changed tthermostat...

I had a lower intake coolant leak two weeks ago and added some block sealant. It fixed the issue and no more leak. Last week driving on freeway truck overheated and stalled. Pulled over looked under hood saw coolant sprayed everywhere, tension pulley snapped, and belt snapped. I replaced belt and pulley but truck would overheat. I discovered the thermostat was froze shut when i tried to turn the heat on and avg temp air came out the vents. Replaced and then all was fine... somewhat..

 

how where the bearings on the water pump did you spin and check for bad bearings on all the other pulleys. maybe that block sealant did more damage then good i could never trust that stuff prob wouldn't hurt to fix the lower intake leak and do a flush

 

Yes water pump spun freely. When its 75 or below the engine temp isn't a problem. When its 75 above it usually is..

 

I agree, fix the intake gasket and do a complete flush... hopefully that block sealer stuff will come out too.