Hi all,

I was tuning my car on the street the other day all seems to be ok, went back home, in the way back I stop at a friends house for about 15-20 stop the car, once i started the car, maybe 5 minutes later, I saw my Hondata showingECT at 200 f which is getting past my normal temp. I have set my fan to come on at 180 F so temp, rises to 190-195, so as soon as i could, I stop, by then my temp went up to 216-220, I wait till the fan cooled the motor down,

check both rad, hoses and noticed, upper was hot and lower was cool, So I suspect a bad thermostat, (Honda oem, only 6 months old) So I replaced it with a new Honda Thermostat, and went out to test it, no overheating issue, til, yesterday that after i did some pulls, finish them and park, motor running and out of a sudden temp began to rise again, out of my normal temp. to 21 F this time. same deal upper hose hot, lower cool. Overflow tank spilled coolant just like the thermostat was fully closed.

When I replaced my Thermostat I test both old/new and both open up, old just a tad less but nothing major,

Things I did, replace thermostat, bleed cooling system, check for leaks, changed my radiator cap. and just today I removed the thermostat. and my temps were around 177 F so I set my fan control to switch the fan on at 185 F instead of 180F went out to keep tuning my WOT part, and temps remain at 183-185 F which are ok,

Do you guys have any idea what is causing this weird issue? I mean I thought it was either my water pump or a blown gasket due to excess of PSI (20) but was leaning towards the water pump. but today both were ruled out leaving the thermostat as the bad guy, but hey it was 1 or 2 days old. Honda OEM.

Hope someone can have some positive feedback as i do not want to put another thermostat and a day later it wont open.

Thanks

 

How did you rule out that it wasn't the water pump? How did you rule out that it wasn't the head gasket?
Also, if you're concerned about any thermostat, boil it in water and watch it open and close after you turn the heat off.

 

I ruled out the water pump, as i removed the thermostat fired up the engine, remove rad, cap and saw a good coolant flowing, thus water pump working, as for the thermostat, I already heat up and let them cool down, they both open and close as heat rises and lowers, as for the head gasket, I just think as I run some test pulls with no thermostat, and car did not overheat then thought Head Gasket was ok.

Any more ideas?

Thanks

 

Try to see if you have obstruction from any buildup in the radiator first. Perhaps flush out the radiator or swap a radiator before attempting head gasket.