97 Pontiac Grand Am -- periodically dumping coolant

I have a 1997 Pontiac Grand Am, 2.4L 4 cyl 135K, that periodically spills coolant on the ground.

My son reported that the “coolant low light” illuminated. The temperature guage remained in the normal range. I checked the coolant level in the surge tank (the only possible check) and added nearly one gallon of dexcool. Surge tank was full but low coolant level light would not go out.

Two days later I replaced the low coolant level sensor but still the light would not go out. Coolant level was OK. Son drove car two days and then reported temperature guage was creeping up toward the red. He pulled over fast and shut down the car. Cooling fans were spinning.

I arrive 15 minutes later with a gallon of water. We add the water, start the car (temperture is in the normal range) and drive to the mechanic (10 minutes). The mechanic kept the car one day and “checked it out.” No problem found. He adds 1/2 gallon of dexcool and says don’t worry. We leave the mechanic and drive to the gas station (3 miles). The car spills about 1/2 pint of coolant on the ground at the gas station, but no overheating. I have since replaced the radiator cap. Hoses appear to be sound (mechanic would have caught that?).

What do I do next? Thanks for any help.

Has there been any check engine light? If so, have the codes read and post them here. (Just the letters and numbers)

Hopefully you are only filling the coolant reservoir to the FULL COLD mark only.

The ‘mechanic’ says he found nothing wrong, but adds 1/2 gallon of coolant anyway. What’s going on here?

If there is coolant on the ground under the engine you CAN find the external leak. Come on now.

You have one of three possibilities.

  1. A leaking intake manifold gasket. If leaking EXternally, it’s likely leaking INternally too.

  2. A leaking head gasket which is pushing the coolant out of the coolant reservoir or,

  3. a leaking water pump or hose.

I wouldn’t trust this ‘mechanic’. Take the vehicle somewhere else and get another opinion.

No check engine light.

Would (1) leak all the time? I had that problem with another car and the leak started slow, but was steady.

Would (2) push coolant all the time or just when the engine got hot?

Regarding (3), the top and bottom hoses look good and get hot. Not sure about the heater hoses…

Thanks Roadrunner. I’ll try the second opinion.

Did the mechanic pressure test it, and test the rad cap? You might have fixed it with the cap replacement.

I’m not sure he pressure tested it… He is not the most verbal of people. (Language issues.) He does seem very trustworthy; he doesn’t squeeze the wallet or pressure for fluff services… I would like to prevent a major failure and BIG expense.
Thanks Beads!

  1. Once an intake manifold leak starts it won’t stop

  2. To be honest, I’m not sure if the blown head gasket would eject the coolant all the time (I imagine it would if the leak were bad).
    When the engine is very hot the coolant will almost be boiling and will be forced out the coolant reservoir (overflow).

Someone else with better knowledge on this subject would know and hopefully respond.

2nd opinion and diagnosis – bad heater core $,$$$.

If it is the heater core leaking, you don’t have to change the heater core, now. You don’t have to change it ever, if you don’t want heat. The mechanic can plug the hoses going to the heater core. Problem stopped.

Have the problems with Dex-Cool been solved. I remember when this coolant left a sandy residue and could really affect heater efficency? An extensive flush with neutralizing chemicals and heater hose and thermostat removal was required to get your heater back (per GM)