Alright guys I have a 88'dx with ls-vtec with a pr3 ecu. I have a stock LS water pump and oil pump. Ok here is my problem when I drive my car I can drive for a little while and its ok but after about 15min of consistent driving no matter what speed it begins to overheat. When I come to a stop it cools back down to normal temp when I just let it sit and Idle for a min. I have already replaced the thermostat and that didnt fix the prob and I also replaced the radiator cap and flushed out the cooling system and neither of these helped Ither. Anyway if any of you have any input it would be greatly appreciated. I am completely lost. I am going to replace the radiator this coming thursday or friday but does any of you have any other things to try. Oh yea and I also did a compression test to make sure it wasnt a blown head gasket or my head bolts dethreading my block and it wasnt this either PLEASE HELP!!!!!!!!!!!!

 

bump

 

Is your cooling fan coming on? I'd also highly suggest changing the oil pump to a vtec one.

 

even though you replaced your thermostat, have you checked to be sure it is opening? also when your car is running with the radiator cap off check to see if you can see the coolant circulating through the radiator