Over heating when still

[dylan94sierra]

Iv been having an over heating problem recently. When ever I'm idling or sitting at a light for a long time it can rise to 240-250. Then I start going down the road and it drops back to around normal 210 or even cooler. I just replaced the fan clutch thinking that was it but it's still doing it. Thanks

 

[kennythewelder]

Most likely the radiator needs to be rodded out, or replaced if there are no leaks in the system.

 

[Big D]

Iv been having an over heating problem recently. When ever I'm idling or sitting at a light for a long time it can rise to 240-250. Then I start going down the road and it drops back to around normal 210 or even cooler. I just replaced the fan clutch thinking that was it but it's still doing it. Thanks

I had a similar problem and I didnt have leaks in the system. I changed out the thermostat and thoroughly flushed the system, Put in new universal Green coolant and water.... and it never goes above operating temperature.

the coolant in my radiator had been in there a loooonnng time...

 

[dylan94sierra]

I flushed my system a little while ago (less than 5000 miles ago) and more recently replaced my thermostat with a failsafe one that should stick open if it were bad

 

[kennythewelder]

I flushed my system a little while ago (less than 5000 miles ago) and more recently replaced my thermostat with a failsafe one that should stick open if it were bad

This conforms a radiator issue. The cooling tubes are slightly pluged up, and need to be cleaned out with a rod that fits inside the cooling tubes, just flushing the radiator out isn't enough to unplug the cooling tubs sometimes. As the truck sits still and the engine is running at operating temp, it only has the air flow that the fan is pulling across it, and the coolant is flowing at a slower rate then when you are driving down the road. As you drive, the air flow and speed of the coolant flow picks up making the radiator more efficient. I have had this issue my self several times. Pull it and have it rodded out at a radiator shop should fix your issue.

 

[90halfton]

Had this problem and tried everything. Pulled radiator out and thoroughly washed out the fins (very time consuming if doing correctly), flushed radiator and motor/ heater core, new thermostat, new fan clutch, rinsed out and straightened condenser fins. Still overheated. Swapped out the radiator cap, never overheated again. Will idle on a 100 degree day with ac on and never go over 185. Not saying this is your problem, but a lot of people have fixed their overheating issues this way, only after trying everything else.

 

[dylan94sierra]

Had the radiator rodded and turns out that wasn't it only about 25% blocked. I believe it's the gauge in the dash they put the heat gun to it and it read around 190-200 and the dash said 230