Recently I was driving my truck and noticed that the engine temp wouldnt go above 180. This was abnormal because the truck always runs at 205 reguardless of the temperature outside. Im not positave but I think the thermostat is stuck open, what do you guys think? Thanks

btw its an 05 silverado 1500 5.3L

 

that would be my guess..

 

Does the temp fluctuate depending on speed, load, outside temp, etc?

 

Not at all, once its up to 205 it stays nomatter what. I have never seen it run above 205.

 

No, you've misunderstood. Now, when it doesn't run over 180, does the temp fluctuate?

 

Ohhhh sorry. It does fluctuate some, it will go up to around 185 than go back down to 180. I haven’t had a chance to really drive more than a couple miles because it was wrecked last week and I don’t have headlights or turn signals on the left side and im not trying to get pulled over. This was not a problem caused by the accident, it was happening before also. I will take it out today and keep my eye on the temp. gauge and let you know what happens. Thanks

 

thermostat is reasonably cheap for that truck and easy to get to why not replace it and see what happens?

 

common on chevys. mine on my s10 got stuck open and it threw a check engine light in the winter time for coolant temp to low.

 

It really does sound like a thermostat. They are really cheap, and if it hasn't been replaced in a few years it would be good insurance.

The reason I asked about temp fluctuation is that if the T-stat is stuck open, the temp will go up and down with engine load and radiator airflow, because roughly the same amount of coolant will be flowing regardless of temperature. So under high load the temp will climb, and as speed goes up the temp will come down, because there isn't flow regulation from the T-stat opening and closing like it should. It's just a good indication of what is going on.

 

not if its a 4.8/5.3/6.0. the stat is part of the housing, and its about 40 bucks.


a simple check with a non contact thermometer (aka Raytek gun) will tell you if its stuck open or not.

its somewhat common on them, but its a good ideer to test it before replacing it.

and make sure that the cooling system is bled out after you do it, those engines are bad for getting air pockets that are a bitch to bleed sometimes.