Here's the deal. I have a JDM B16. The motor was running on cold while driving. So I replaced the thermostat, or lack there of, with a jackson racing 160 degree thermostat. My car didn't have a thermostat when I pulled the housing apart. Now I can let my car idle all day long and the temp reads normal. I start driving for a little while and the temp goes up. As soon as I crank the heat to high it drops immediatly. I hard wired the fan and it does the same thing. I have bled the system numerous times and that has not help either. Any ideas????

 

IF its not leaking/losing fluid is it ?assuming there are no leaks & the cooling fan is working,check the water pump for leakage,Also be sure that the radiator is circulating antifreeze & has nothing blocking the the fins on the radiator.....

 

if theres no leaks my guess would be something is clogged. u dont see honda water pumps break very often.

 

Ummmmmmm, Keith.... I believe he said right there that he already did that.... Its ok we know that skimming is better than actually reading the post.....

 

I did that tard! There are no fluid leaks. And it is still doing it. This is going to drive me to drink.

 

water temp sensor?

 

I thought that too. but it doesn't make sense that when i turn the heat on the temp drops off.

 

This maybe stupid, but are you SURE the thermo you got isn't faulty?

 

That was the next step. I have an extra one os I'm going to change it this weekend. It's just strange that the motor didn't have one at all.