I start my truck drive about 10 minutes while watching the thermo go up past the 180 mark to about 210 then drops to 180 till i shut it off.It is a 180 thermostat I thought it was the thermostat so i replaced it and the new one did the same thing what could it be. Please advise on what to do to fix this I dont want ti to keep geting to hot it didnt always do that I was trying to figure out what i did different I think it might of started when i took the raidiator out and had it rotted out Iam not shure Thanks for any input.
Thermostat Woes This is interesting as you say the temperature peaks then drops back to normal . It is often helpful to drill one tiny hole on the flange part of the thermostat as this allows air & steam to flow past reducing the possibility of air pockets in the cylinder head . Have you placed your hand on the radiator core with the engine running ? (you'll need to remove the upper baffle to do this) because this is a simple way to see if the radiator has clogged tubes or other restriction ~ maybe they left some crud on it that's restricting the flow .
thermostat pin hole thanks nate when you say flange do you mean the circular part of the thermostat and if so ill try that thats easy enough. thanks
Thermostat Mod Yes , the flat(ish) part between the sealing edge and the working center valve part . One tiny little hole does the trick ! . Some modern thermostats have a wobbly rivet there for just this purpose .
