First, an exhaust valve will not cause pressure to be forced into the radiator. If you have a burnt exhaust valve, it will allow the leak to enter the exhaust. Also, an intake will allow compression to enter the intake and not the cooling system. If you have pressure from the engine entering the cooling system, you have a bad head gasket.
As far as the radiator leak, it sounds just like it is. Chances are there is a leak that is in the radiator and running down the rad and on to the floor. When you removed the lid from the overflow, you allowed air to enter the system and thus, more coolant could leak.
What I recommend is this. To identify where the coolant leak is coming from, have the cooling system pressurized. Check the radiator for where the leak is coming from. If you can't tell, they make a dye that can be added. Place the dye in the radiator, drive the car for awhile, then using a black light, check for signs of where the coolant is coming from.
Honestly, a burnt valve will not cause pressure to enter the cooling system. It couldn't. The exhaust valve ports to the exhaust system and the intake valve to the intake manifold. Neither of which should have coolant in them. 99.9% of the time, it is a bad head gasket.
Let me know what you find. The leak is either the radiator, a radiator hose, or a heater core hose.
ALSO: Your heading mentioned transmission fluid leaking, but you didn't mention it in the posting. Is there a problem there too?
Thursday, November 19th, 2009 AT 10:59 PM