How do you check for internal leaking on a 99 malibu in regards to overheating i have a v-6 3.1 motor i have changed almost everything under the hood could it possibly be the cap on the overflow?

Answer

When a engine consumes coolant and there is no visible leakage on the ground, this can be caused by a leaking head gasket or intake gasket which allows coolant to enter the combustion chamber where it is heated and turned into steam. A pressure cap will generally not cause this type of problem. I would suggest you bring your car to a reputable garage and have them do a leak-down test to the cooling system. This will give you a good idea of the extent of the problem.

Answer 2

This happened to me too. I couldn't see any coolant leak, but could smell coolant under the hood sometimes. Turned out to be a leak in the heater rad core, which is used to heat the car interior. It is located on the firewall IN THE ENGINE COMPARTMENT, not inside the car. When it leaked, it dropped down on the catalytic converter and evaporated, so no leaking fluid was visible.

First answer by 1930fcoupe. Last edit by Tpeters001. Contributor trust: 0 [recommend contributor]. Question popularity: 21 [recommend question]