You will be much better off going to this site. There are some fairly sharp people over there.

http://ths.gardenweb.com/forums/cars/

OK, you bought a used car with a cracked coolant overflow tank and probably a failing/leaking water pump. It is possible that before you bought the car or during one of your 'low coolant light' episodes, the engine could have overheated enough to slightly warp the cylinder head causing a small internal coolant leak. This could give you the symptoms of no external leak but constant coolant loss. A good mechanic should be able to diagnose this condition. This type of repair isn't cheap, though. There is also the off chance that it might also be some other, different problem.

There are some very important things to remember now:
- Adding coolant just to the coolant overflow tank won't protect your engine - you will have to add coolant directly to the radiator. Adding coolant to the external reservoir only puts coolant back into the engine slowly, and that is only if there is no big leak in the engine cooling system. With a known engine leak, when you need coolant, the engine needs coolant NOW, so you need to add it directly to the radiator first, and then top up the overflow tank.
- Only add coolant to a cool engine/radiator. Opening a radiator cap immediately after driving is potentially very dangerous due to hot steam that can severely burn you. Wait a half hour after driving to fill the radiator or fill it first thing in the morning.
- With winter approaching, use a 50/50 mix of antifreeze and water to fill the radiator. Filling the cooling system with water and then experiencing freezing weather can lead to a frozen and cracked radiator or engine block. A new radiator isn't too much $$, but an engine is!

Both my daughters had Grand AM GT's ('96 & '02') with 3.8L engines and both had this same problem. Chances are that the intake manifold gasket leaks. Engine heat will dissipate the fluid but it may eventually become a leak that will cause the antifreeze to mix with your engine oil. This was a common problem with the 3.8L engine until fairly recently.

I haven't messed with a grans am in a while but most new cars do not have a fill port on the radiator anymore. To ad coolant to your system you will need to fill the coolant tank, this is not an over flow reservoir like on the older cars. Most of the time there is an air bleeder somewhere on the top of your engine that looks kind of like a greese fitting, usually where the upper radiator hose connects to the engine. If your coolant level has gotten to low you will need to loosen this fitten while the engine is running to bleed any air out of the system, you should notice the level in your coolant tank going down as you do this.
As for the lose of coolant but no drip? Most likely cracked or warped head, or a intake manifold gasket. If it is a head problem you should smell the antifreeze burning, a sweet smell coming from your tail pipe and/or notice the oil looking milky. If the intake seal is the problem you should be able to see steam coming from the engine or notice the oil looking milky

I dont think grand ams came with the 3800 engine. The grand prix's and bonnevilles did. But you are correct...the intake manifolds were a weak point in this engine. Its about $700 to replace the manifold which is made out of some kind of synthetic material.

Hi, I have a 2001 Grand Am SE. Does my Grand Am have a fill port on the radiator. I put the 50/50 coolant in the plastic coolant tank. I hope I did the right thing. The guy over at Auto Zone said that was right. Thank You.

Ok, first off, what engine do you have? 3.1, 3.8, 2.4? I am going to guess 2.4L 4 cyl. I worked for several years as a GM dealer service tech. If you have the 2.4L then you probalby have a blown head gasket/cracked head. These engines are known for that. Not as much as their predecessors, the Quad Four, but they do have the same problems. They are just a slightly updated version the the Quad Four, but with the name 2.4 Twin Cam on top instead. This will most likely be expensive, but you should get it checked out and if needed repaired soon. Water will not damage bearings imeadietly, but the glycol in the coolant most certainly will.

If you have the 3.1L then you probalby have a blown intake gasket. These are known to leak oil externally as well as water both externally and internally. If the water/coolant mix gets in the oil, thats bad for the engine bearings. This will not be as expensive to fix, but will be about 6 hrs labor.

If you have the 3.8L, there is a plastic fitting, I think on the passenger side, on the engine for the heater hose to connect to the intake manifold. These will crack and leak. Sometimes the come completely off. If this is the case, take the old one off and take it with you to the dealer's parts department. The counter man will probably know what is came off of without you even telling him (that's how common this is). The new one is steel and costs $10 or so. It won't break like the old on. The only trick here is that you may need an easy-out to get the part that is broken out of the engine. The 3.8L also had some issues with the intake gasket, similar to the 3.1L. I have also see the upper intake plenum crack on these and leak water into the engine making you think you have a bad head gasket.

Anyhow, check the oil for coolant contamination. If it has coolant in it, it will be foamy or look like a chocholate milk shake. If is looks like this, this is bad. Get it fixed NOW. You will damage the engine. Otherwise, you should probably buy/borrow/rent a pressure tester and check the system for leaks. With this aparatus, you remove the radiator cap and pump up the tester to pressurize the system. There is a gauge on the tester, 16-18 psi sould be good. Them watch the gauge for the pressure to drop. If it does the you have a leak somewhere. Look all around for any seepage or drips. While is is rare and would not be likely on this new of a car, be sure to check for cooland dripping around the starter/flywheel area. There are two freeze plugs in the rear of the engine block, behind the flywheel. If one is leaking you must remove either the engine or transmission to access them for repairs.

When you add coolant, do so with the engine cold. Then remove the radiator cap. Fill the radiator completely full. If there is air in the radiator, then the engine can't suck coolant from the overflow tank. Put the cap back on the radiator. Then check the overflow tank and fill it to the cold mark as needed.

Good luck, and please let us know what engine you have.

I have the oposite problem in my 1999 trans am. I did not know that there was a coolant low light. I bought the car 7 years ago and had to open the filler cap to see if I had antifreeze, because you can't see through the plastic of the tank. Shorting the contacts on the sensor can't turn off a light that already is off. So now what is next?