water problems

okay, I have a 1994 Grand Am, Quad 4,2.3L with a water problem. I am fixing to put in my 5th heater core. started tearing it down, and going deeper this time. I have replaced the water pump thermostat at the pump, the H hose that connects to the heater core (2 times). Found out tonite that there is another thermostat at the top of the engine where the big radiator hose connects. Is this right? 2 thermostats? Also the resivor has 3 hoses coming off of it. 2 small ones at the top, and one larger one at the bottom. The bottom one goes to the bottom of the radiator by way of a T hose, and one of the top ones go to the top of the radiator. The other is a vent, or so I thought. I found on the underside of the top inlet that a steel line had been pinched of and brazed together. A GM parts guy keep telling me that the line had to circulate back thru the engine, and that it didn't need a vent. (closed system). Will fixing this cure my heater core problem? Give me some answers please. The car runs like a top. Just can't keep fluids in it. Help

okay, I talked with a GM mechanic freind of mine. He said it only had 1 thermostat, and it was at the water pump. Also said it was a common mistake that people put one on top. He said that if it were put in the way you would normally think, it would be backwards, thus causing a blockage.
He also said that the flow was revese from what you would think. It has been removed and on the road for a day and a half. so far no leaks. I'm keeping my fingers crossed.

sounds like you found your problem, there should not be a thermostat on the quad 4 anywhere but below the water pump! The two were fighting each other, making your car overheat & drop the coolant. Did you fix the steel line that runs along the back side of the motor to the water inlet (plastic piece on the drivers side of the head that attaches to the top radiator hose)? That line should be open, not sure what affects that would have if it were crimped off, but its designed to be open.

yes we did. We took a piece of steel gas line and ran it back to the hose it was suppose to be attached to. Had a little more air in the system this morning, it was the first time since we have been chasing this problem that I have ever seen the pressure cap work. I think (hope) we have finally fixed this thing. I know it has about drove all involed nuts. thanks for your response.