A buddy of mine has an S2000. THe antifreeze will not circulate and his engine over heats. It does not lose antifreeze, unless the engine has been ideling and warmed up, and you remove the radiator cap, the antifreeze will spew out. The water pump has been checked. Its ok. The thermostat has been replaced a few times. The thermostat housing has been removed and cleaned. The sensor has been checked. The radiator has been removed, check, cleaned, flushed, and pressure checked. Its ok. There is not water in the oil. No condensation from the exhaust. And the timeing is on. What could the problem be? He says that when he bleeds the pressure valve, the water circulates, but after a while, the car heats up...the bleeds the valve, and it recirculates, car cools off. What is the deal???

 

You may just have ALOT of air in the system...just keep bleeding it and see if it works, if not, you may have to have a garage use a machine to remove it from the system...that sounds most likely like your problem, i was going to say bad water pump but you said it was fine, so most likely, just ALOT of trapt air in the system.

 

As he has bled the system, has he added any coolant to it? I should hope so if there is that much air in the system.

 

you checked the sensor, but did you check the thermo fan switch sensor? ... if that sensor doesnt work then the fan wouldnt turn on ...

 

Fan turns on. Everything as far as a cooling system works, is functionaly....that is on the external of the engine, such as fans, radiator, thermostat and housing, pressure reliefe valve, hoses, and water pump. and the timeing is on. so dont know?? The whole idea that was mentioned about "having alot of air in the system" is a good suggestion. I do not know if he has ever filled the radiator fluid, released the pressyre, and refilled it, and released the pressure again yet or not? I have to see.

 

Anymore suggestions....

 

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check the overflow lines...a clog in that will cause the car to go bonkers. well, it did in my FD rx-7. also when you burb your car, you should take off the cap...let the car come up to idle for a good 10 minutes. in this time bubbles should come up and you should be filling the car up to the top at all times.

also be sure to use distilled water because if youre using city water or anything with ANY type of calcium it'll stick to your radiator fins in about 2 days time...and then youre buddy will be out 500 bucks.