Volvo: mystery coolant, head gasket, combustion chamber

Question
hello saul here with this problem my 850 runs good but no heat and the reservoir starts empty whe the temperature goes up starts filling up and bubles like is overheating but  is not, i change the thermostat i open the purge to get the air out but still no heat look like the coolant its not pump from the waterpump but the weird this is the car dont overheat  so thats the mistery coolant please advise

Answer
Saul,
If there are bubbles in the cooling system you could have compression leaking into the cooling system. That might be a bad head gasket or warped or cracked head, and the coolant is getting burnt in the combustion chamber. It is time to get the car to the shop for further testing. Sometimes the heater core leaks, and the coolant ends up inside the car.