For about 2 or 3 years now my pickup has been overheating every once in a while. Usually it will temporarily overheat and then the gage will go back to normal (pressure build up). Ive replaced the thermostat twice, and got the water pump and radiator replaced, but it still happens. This last time the gage didn't go down so I had to pull over and shut it off for a while. I let the truck sit for a day at my house and now its working fine....until the next time it occurs again. Im not sure my mechanic knows the answer and i dont want him to keep guessing and dump money into it. What else could be the problem? Thanks in advance for your help.

 

Make sure ALL the air has been bled from the cooling system.

 

Has the hole system been fully & properly back flushed? Replace the thermostat & radiator cap with genuine parts. Maybe install a secondary temp gauge to verify temps.

 

Yes. When the problem initially started happening and changing the thermostat didnt work my mechanic flushed it and replaced the cap, then the water pump and radiator were replaced and the thermostat again. After I drive it for a while (even if it doesn't over heat) when I shut the car off you can hear a gurgling noise. Obviously pressure is being build up. Could it be the thermostat housing?

 

Does it have an electric radiator fan or a viscous fan run off the engine?

If eletric, check that is working, if its Viscous, check the friction of the fan hub when cold v's hot.

I've seen vehicles randomly overheat due to worn out viscous hub on the fan.