92 Grand Prix loosing collant but not leaking anywhere, what could be the problem?

Question

Okay I have a 92 Pontiac Grand Prix, recently our low coolant dummy light came on, then turned off. I checked the coolant level and it was fine. It did this for two days then a leak developed at the water pump where it connects to a set of hosing leading to the throttle body and back around to where I can't see. I fixed this leak and waited 24 hours for the RTV Blue Sealant to cure. I started the car today and it fired up quickly. As I drove down the street the water temp gauge shot up past the red and the low collant dummy light came on. I pulled over, turned of the engine, and checked the collant level, perfectly fine. I waited ten minutes fired the car back up and drove home. When I got home I check the fluid levels again and found I lost alot of coolant but there is no steam coming from the exhaust and no collant in the oil and no leaks anywhere. My question, what could be the problem? Can a bad water pump exhibit the signs described and loose collant without other signs?

I'll also add that when I shut off the car there was a burping like sound from the upper radiator hose where it connects to the thermostat.

I did check for the heater core (as I have an 85 Corwn Vic that had this problem), no leaks and no smells. I checked the oil there is no bubbles or any indication there is coolant in the oil. Just an unexplained large loss of coolant. Thanks in advance.

Answer 1

first you might have had a air pocket in the cooling system.
second, check under the passenger side floor matte for a possible heater core leak. third. you probably have fixed the problem when you found the leak and repaired but as i mentioned before you had an air pocket and by getting it hot and then shutting it off it bled itself out showing signs of coolant loss, hope this helps

Answer 2

You may have a blown head gasket. Check the oil. If there is bubbly oil, then you are loosing the coolant into the oil.

Go to a mechanic. They have a thing that they put onto your radiator fill spout.
They pump it up like a bike tire pump. If there are any leaks anywhere, the pressure will drop, and if you are lucky, you will be able to see exactly where the leak is.

Answer 3

Any smell of antifreeze in the car? Maybe a leaking heater core, could even be a leaking head gasket (you won't always see smoke). Go to NAPA and buy a cooling system tester, you pump it up and pressurize the cooling system. That's how I check for leaks.

Answer 4

check that thermostat!!