i read somebodys post and they said,they changed their cap,and the car ran cooler ,is this possible?if so please xplain. thanks T.T

 

Well, if the cap is not a tight fit or doesn't actually seal the rad to the 15 lb. per square inch advertised limit (that is just a number off the top of my head) then the system will have a lower boiling point and can't cool to its design parameters.

 

Well mines 16psi but Bull is right a bad cap can cause cooling problems by venting off coolant that needs to stay in the system. Less coolant=less heat removed=hotter engine.

 

Actually, it is the increased boiling point of water under pressure that lets it cool better without boiling over. The boiling point will go from 100*C to say 120*C if the system is kept at 16 pounds per square inch by a cap that won't vent until it hits 17 pounds.

Numbers aren't exact but you get the idea.

 

Actually Bull I got the idea when I took my Heat Transfer and Fluid Flow classes......but not everyone has been through that so I try to keep my explanations simple.

 

OK