okay, i put a brand new oem thermostat in my b16a (1st gen in a 90 crx). when car is just ideling (not moving), it wont over heat. but when i drive it, it gets hott. like criticaly hot. here is the weird part. if i turn temperature **** for my vent all the way to heat, the temp will go back to normal. if i have it on cold, it will get hot again. WHAT THE F IS CAUSING THIS!!! PLEASE HELP

 

It sounds like you have a blockage in your radiator or lines, Or possibley a bad fan? When you turn the heat on it opens up your heater core and coolant flows thru it, it acts is a seconed radiator and thats why the temp drops. Check over your cooling system, water pump, hoses and the radiator.

-chris

 

nice thanks chris. problem is, this is a new aftermarked radiator i got like 1 year ago and the water pump is brand new oem. it was installed before my swap back liek 4 months ago.

 

fan is switching fine btw

 

you probably need to bleed your coolant

 

i already left the car running for like 30 mins with the cap off. its this the propper way?

 

check the radiator itself, it may look fine where it is, but if you look at the fins inbetween the actual coolant lines in the radiator, see if they are corroded or falling out or even missing. They acutally play an important role in the radiators efficiency by increasing the surface area of the fins. Since they are usually made of copper on a stock radiator they corrode and break and fall out of between the cooling fins. This happened to my 92 si hatch, I replaced the radiator and thermostat and the problem went away.

 

this exact same problem happened to you?

 

yes, not in the same engine/car, but the same example basically, I bought the car and not long after it started to run very hot, so i would drive around w/ the heat on to keep the coolant level from boiling and overheating the engine. I replaced the thermostat with no change, so I replaced the radiator and the problem went away, the radiator was shot, not leaking but the fins were almost all gone or falling out.

 

Removing the rad cap may bleed the air out but it is not the correct way. You have a bleeder screw on your thermo housing, you open it a few turns and run the engine into coolant comes out.
-chris