99 Grand Am coolant problem

[A_Shaw49030]

Alright here's the problem Im having right now with a 99 grand am se, v6 version. Earlier in the summer I was having a problem where the car would over heat, and my coolant would boil over because the cooling fans wherent kicking on do to a faulty relay circut up in the comptuer. Well the problem that has occured now is for some reason, it keeps dumping my entire coolant tank whenever the car reachs temperatures of 200 degree's farenheit which is where it always usually runs at. I know its dumping the coolant because with the heater on and blowers running the air suddenly goes ice cold and then the car's temperature starts rising rapidly. I do know that it is dumping the coolant onto the ground, but havent checked the oil yet to see if it's dumped any into it, mainly because by the time i got done dealing with the first bit my hands where frozen solid due to the 8 degree temperatures northern michigan is experincing right now. Anyways, Im stumped at what could be causing this, as its utterly bizzare, and almost like my car is suicidal and trying to kill itself. So any one who might have had problems like this before or knows what could be causing it, please let me know as this tempermental car is starting to get on my nerves.

[GTP Dad]

Welcome to AF!!

Make sure to check the oil for coolant as this seems like it could be a leaking intake gasket. If that proves incorrect, bleed the coolant system using the bleeder screw on the thermostat housing. It sounds like you have a large quantity of air in the system and it is causing the coolant not to circulate and that is why the heater is going cold on you.

[A_Shaw49030]

I know why the heater is going cold, its becuase my car keeps dumping my coolant, whenever it reaches 200 degree's fareneheit, what I suspect is the problem is a faulty thermostat.

[A_Shaw49030]

This isnt a slow leak or anything either, its a instant boil over at 200 degree's every time.

[A_Shaw49030]

And just checked the oil supply its completly fine, no coolant in the oil, which leads me to believe perhaps the thermostat is stuck. Any one got any other idea's or suggestions?

[xeroinfinity]

Your heater , the hot to cold or no heat, is because thier's an air pocket trapped in the heater core. Normal when youre loosing coolant.

I'd say youve got some bad gaskets!

[J-Ri]

Check the pressure cap. The system shouldn't boil until over ~260 degrees (even plain water at atmospheric pressure doesn't boil until 212, so an antifreeze mix IS NOT boiling at 200) if the cap is holding pressure. If I remember right, the fans are supposed to kick in at ~220 degrees. If the cap isn't holding pressure, the coolant will boil before the fans kick in. Also, bleed all the air out of the system. There is a bleed screw on the bypass pipe (right above the water pump), and one on the thermostat housing. It may have a line coming off the thermostat housing that goes into the coolant reservoir, if so, you only need to bleed the W/P one. A spill free funnel is great for this (about $12).

[xeroinfinity]

Originally Posted by A_Shaw49030

And just checked the oil supply its completly fine, no coolant in the oil, which leads me to believe perhaps the thermostat is stuck. Any one got any other idea's or suggestions?

It might not hurt to have your cooling system flushed and see if that along with bleeding the air out of the cooling system helps.
A new thermostat would be worth trying too, if it hasnt been replaced in the last couple years.

If you have the proper antifreeze mix you shouldn't be boiling at all.
Here are how the fans are set...

The PCM commands Low Speed Fans ON under the following conditions:

The engine coolant temperature exceeds approximately 106°C (223°F).
The A/C refrigerant pressure exceeds 1310 kPa (190 psi).
The vehicle is shut off when the engine coolant temperature is greater than 140°C (284°F) and system voltage is more than 12 volts. The fans will stay ON for approximately 3 minutes.

The PCM commands High Speed Fans on under the following conditions:

The engine coolant temperature reaches 110°C (230°F).
The A/C refrigerant pressure exceeds 1655 kPa (240 psi).
When certain DTCs set.

Good Luck

[A_Shaw49030]

Yea, after working with a mechanic friend on it for a bit, we found out I simply had a very large pocket of air in the coolant lines which we bled out, and also to the pressure cap on the resevior tank wasn't fittting tightly which was causing the pressure problems and the coolant to flush out through the resevior tank simply because i had no pressure, well its on tight now, the airs been bled out and I havent had any problems recently but still watching it like a hawk watched dinner lol. Anyways thanks for the help and advice everyone. -Andrew-

[xeroinfinity]

Glad to hear you got it fixed !!