The next time you drive your car after you have replaced the cap, grab the upper radiator hose with the engine off. You will be feeling to see if the system has pressure. Check it again in a few minutes to see if it still has some pressure. It should in both caes. If nto there is a leak in the sytem somewhere.
Make sure the coolant tube and the little fitting it goes on has a clear passage for the coolant as it could be clogged.
Wednesday, January 11th, 2012 AT 4:02 AM