1997 850 mystery ( coolant system)

Hippiechick1976 · Post by **Hippiechick1976** » 22 Jul 2012, 20:39

Here's the story. My heater core went. We replaced the heater core and thermostat and we let the car sit and idle to get air out of the coolant system. Air seems to leave and it quiets down. We then took it for a ride and it instantly overheats, coolant bubbles and steams out of reservoir. We did this 2 times. You can hear the thermostat kick on and when the fan kicks on we get more bubble action but it quiets down. Kinda lost..our next guess would be a new reservoir cap but I don't think thats it. It does bubble and steam out when cap is on tight. It's not overfilled, once it cools down the reservoir is empty.....Any ideas?

sit22II · Post by **sit22II** » 22 Jul 2012, 20:52

Sounds like your head gasket is bad

Post by **rspi** » 22 Jul 2012, 21:10

I would 2nd that statement. When the core went, did the car overheat? If it overheats just once it can blow the gasket or cause it to leak. I just replaced a gasket on our S70. It was causing the coolant to boil out of the res tank and was low when the car was cool.

If you need a good cap I have one.

Hippiechick1976 · Post by **Hippiechick1976** » 24 Jul 2012, 09:36

The head gasket has no leaks and no oil and antifreeze mixing. It did overheat but as soon as temp gage went up i turned car off and it cooled down instantly. Literally the temp gage went down as soon as I parked it.

Post by **jblackburn** » 24 Jul 2012, 10:09

How do you know? I would try a combustion gases test on the coolant to make sure that the head gasket is in fact NOT leaking.

A car doesn't cool off as soon as you shut the motor off - it actually gets hotter for up to 30 minutes after being shut off.