Hello I have a 89 prelude that overheats. I just bought it last week and I'm trying to figure out why it's overheating. I drained the coolant added new coolant, installed a thermostat after it didn't even have one. I'm thinking maybe it has the wrong fan switch, since I haven't seen the car turn on the fan unless I drive, and when I drive it over heats after around 5 minutes of driving. I have no leaks since all hose is 2 years old so I'm stumped. Anyone have any suggestions? Maybe water pumpump?

 

Btw after I drive and park it and turn the car off the fans are on. That's the only time I noticed the fans on when the car isn't moving.

 

compression test to see if the head is warped and letting combustion gases into the coolant

 

The fans turning on after engine is turned off is most likely the rad fan control unit turning them on because oil temp is up.
My guess is the ECT switch is bad, to check, unplug the switch and jump the terminals in the plug, to see it rad fan turns on, if they do, replace the switch, if not check wiring between switch and rad fan relay.

As mentioned a compression test needs to be done, overheating within 5-10 min. is not very common. 94

 

Ok thank you both. I will try these methods out from what you both said.