2001 Grand Prix GT coolant issue

[carguy9927]

I have a 2001 Grand Prix GT 3800 V6 with 199,000 miles on it. Recently the low coolant light has been coming on. I filled it with coolant earlier and drove it and when I stopped it was low again. The cap wasnt even hot and when I opened it the pressure bubbled. The intake gaskets and plenum were replaced last fall professionally. What could cause this problem. Any suggestions are appreciated. Thanks

[Tech II]

Well, obviously you have a leak somewhere.......sounds like a pressure test is in order....

[Koscoe]

Elbows...??

[carguy9927]

No its not the coolant elbows. I took it in earlier for a pressure test and they said they couldnt find the leak. They told me just drive it and see if it gets worse.

[Stealthee]

A faulty cap could cause pressure loss and coolant to evaporate.

[carguy9927]

You know, you might be right Stealthee. Because come to think of it the cap wasnt even hot after driving it so I opened it up for a minute and next thing you know, it was hot. I'll try that first and see if it helps. Thanks!!

[FISH96]

please explain how the coolant evaporates because of a radiator cap malfunctioning.

does the coolant in the 'bottle' evaporate? the bottle is vented to the atmosphere.

[Stealthee]

A cooling system is pressurized. If a cap does not seal properly it will cause overheating and the vapors will get past the cap not allowing them to cool and return to liquid form.

The bottle is an overflow only and is not pressurized.