re-started the rebuild motor today, BUT
 

the engine got rough run(I have to keep my feet on the gas petal), aslo, the car is running HOT HOT, when I kept it around 2300 rpm. I can hear the coolant in raditor is boiling. but why is that? I reused the previous themostat cuz the motor wasn't overheated, so I assume the themostat is a good one.)

I can think of anything else to check, besides the themostat. any clue?:confused: :confused: :confused:

thanks

Overheating can only be caused by a few things. Is there enough coolant? Pull the t-stat out and either check it or get another one anyways. If coolant isn't leaking(which can be tested by a pressure test from a good shop for less than $50 usually) then it has to be blocked or the fan clutch could be bad.

I say ditch the t-stat first and see if it helps. Check for leaks yourself also. If it doesn't help then check the fan clutch.

Did you bleed the cooling system? Maybe you have air stuck in the system.

tried with another used themostat today, still running HOT. I saw the niddle was raising when I rev about 2000 rpm.

I think there might be some air in the cooling system. how can I burp those air out of the system?

thanks

There is a bleed screw at the top corner of the rad (passenger side). If this is not present, the best way I have found to bleed is to alternatively cover and uncover the coolant filler hole with your hand, while you pump the rad hose...Every few pumps, stop and top off coolant....Also, do a search for the "bubble test" to find out if engine is eating coolant.

thanks, but I don't see any white smoke. if coolant goes into engine, it will white smoke.

possible to leave the rad cap open, and have someone to fill the coolant when I rev the engine inside. I have been testing by myself.

will try again.