deanjet

Hello, I wonder if anyone can help. A few weeks ago the truck was running fine, but I noticed the water pump started leaking. I put a new water pump in. The first few times I drove the truck, it would over heat when I stopped, and about 1/2 gallon of water would burp out. It did that a few times, I assume all the air is out of the system now. The truck still over heats at traffic lights. It cools back down when it gets moving again. The radiator is full, it is not leaking, no blockage that I know of. I am guessing a bad fan clutch, what do you think?

Purplehazeir

Pressure test the cooling system, flush the cooling system, replace the T-Stat and try again. If it's still over heating, then look at the fan clutch.

deanjet

Ended up being the fan clutch, it just happened to go out the same time that the water pump went.

kkaterinabella

Glad you found your problem.

However, if you still have the original radiator or have replaced it with the same size radiator, taking off the cap to check your fluids before you drive it, will cause your truck to overheat and consequently cause it to overflow thru the overflow tank. It was explained to me that (as you already seem to know) the air trapped inside the radiator is what causes the thermostat to malfunction and the radiator to overheat.

Be sure to add fluids thru your overflow tank/coolant reservoir tank instead of taking the cap off.

I found that when I replaced my standard radiator with a "super duper heavy duty" radiator, (that is how the worker at the parts store described it to me), I had less problems with over heating. I could even check my fluids without problems before driving it.

Unfortunately, when I replaced the last radiator, I went back with a regular aftermarket radiator. I had forgotten the overheating problem that the regular-sized one caused!!!

Hope you went ahead and replaced the thermostat. In the process of replacing 3 radiators (one unfortunately had a leak when I bought it) I have had to replace 2 water pumps, and 2 thermostats. It has never failed. Every time the water pump has gone out, I have had to replace the thermostat.