O.K. sorry I have not posted in forever. Well on to the problem.

Driving around, she is fine. If I sit idle for over 5 minutes or so she starts to overheat. If I kick the heater on she cools right back off.

I thought that if the heater cooled it down it was not the thermostat. Any ideas?

98 EX d16y8

 

Trouble-Shooting Guide: Car Overheating

Overheating at idle is easy to figure out IMO.

Does your fan come on? If the heat coming from the climate control is warm/hot, I would assume that the Tstat is functioning just fine.

 

Got it figured out. The switch on the t-stat housing is bad. I broke out the multimeter and some jumper wires. Tested everything and its the switch. Relay is working fine, the upper radiator hose is hot just the like the manual said it should be. No head gasket leak after raising the front, removing the radiator cap, and reving the engine.

When I jumper the t-stat housing switch the fan kicks on like a champ. So I am off to grab a new one. Thanks for the reply. HCF is still the best.

 

Overheating only at idle is usually because the radiator fan doesn't come on. Bypass the fan switch on the thermostat housing (unplug it and put a jumper wire in the plug on the car side). Confirm that the fan now starts immediately when you turn the key on. If not, check the fan motor, fuse, and relay. Test drive with the fan running all the time. If no overheating, replace fan switch.

 

I've got this same problem, but i jumpered the switch, the fan is continuously running, and the car is still overheating during idle only. thermostat has been replaced and is working.