I recently fixed a water leak on the driver side of the Quad 4 engine of my Grand Am. To all who may come up against this problem, I have a couple of suggestions you may wish to read. The P Gr Am has plastic piece of crap water neck on the driver side of the car that breaks down and deteriorates after a few years. the O-ring that seals the coolant from leaking does the best it can, but eventually the plastic piece of crap water neck housing just disintegrates. I faced replacing the water neck with a factory part and waiting until next weekend to complete the repair or making do on July 4th weekend. Coolant had been leaking out for awhile but I just refilled until it got so bad it was leaking out on the driveway overnight. First of all, ensure the leak is from the drivers side, not the passenger side. If it is from the passenger side, you probably have a water pump leak and I cannot help you with that. If you are a brave soul, then replace the water pump and do the timing chain as well while you're in there... Save a buck or two. Anyways, if the leak is from the drivers side, your water neck is probably broken down. You will need to drain the coolant (quick way is the remove the lower radiator hose into a gallon or so clean catch pan so you can reuse the coolant) the freaking drain plug is hidden like the low pressure valve on the AC (we build excitement? I think they build mystery...) Once the coolant is mostly drained, you're ready to go. Struggle with the stupid spring clamps and get them off of the upper radiator hose and the upper heater hose, taking care not to ruin either of them OR the plastic piece of crap water neck housing, no matter the temptation to do so anyway (replace with gear clamps! Tighten snuggly but do not be over tuff). Unbolt the 10 mm mounting bolt for the pipe that goes some damn where on the other side of the engine and into the water neck housing. I unbolted the 14mm nut/stud that held the whole pipe thing down and removed the whole pipe thing, but later decided that might not be necessary. Once the water neck is removed, if there is still some 'tube' left on it (I had 3/4 inches of plastic tube still left, where the indentation for the O-ring was supposed to go, there was also still fully 1/4 inch of plastic tube that fitted into the engine left), clean it up with several clean rags, cloths, etc. until it is clean and dry, ensure there is no coolant trickling out of the engine where the housing will be installed, if so, absorb it all with a rag, clean with rubbing alcohol, lacquer thinner, etc. Clean and dry is the rule. Then use a product named "The Right Stuff" It's about $ 13 bucks but well worth the cost, Slather it (ignore the intrux, put about 1/2 inch all the way around the thing) onto the water neck and all around it and then stick it back onto the engine, replace the water neck bolts , torque 'em, then go have cold one or do dinner, and let the "sealing" begin. It will "squish" out all over the place. Ignore that. Enjoy the brew or the dinner. Come back in 30 minutes or so and buckle down all remaining bolts, etc. I used high temp RTV sealant for the tube that goes over to the other side of the engine, and it seemed to work well.
Anyways, that's my fix for a leaking piece of crap plastic Pontiac water neck housing that should add a couple of years life to your Grand Am water neck. No Caveats from my end, my middle kid is driving the car right now and no complaints, I hope it is working, hope it works for you as well... Good night!

 

im facing the same problem..i broke the replacement one and had to get new one..it dont take kindly to being messed with too much..like hose removal and stuff. i need to replace the gasket i hope..but i wish they would put more than 2 bolts to hold it or at least make a gasket that works..ie t-stat type..ill try ur idea and see how it works..