ok so i got a 89 f150, runs good and runs cool ruless you drive it for a while then let it sit running then it will get too hot somtimes but i think the electric fan i put in isnt strong enough.

anyway when i drive it runs great and doesnt overheat but the cooling system seems to build way too much pressure in the hoses and blow into the overflow. i replaced the cap froma 13 to a 16 and it still does it. ive alrady repalced the pump and thermostat. so im really confused. I was thinking head gasket but i dunno i have no indicators of a blown gasket. I do knwo that the heater doesnt work either heh

 

Is the electric fan truning the correct direction? Why was it installed, was it getting hot before? Have a qualified guy do a block check to see if there is CO2 in the coolant.