Pressure in Coolant Tank

Volvos have some screwy system with a main tank and an overflow tank. With a bad compressor, it blows all the coolant from the main tank to the overflow, then it shuts down because of low coolant.

The truck I am driving blew it out through the cap, and every other day I would have that problem. Putting a head gasket on a compressor is as expensive as putting a reman on.

 

Start cheap and replace your pressure relief cap. Make sure if you do a pressure test you use that spot where the pressure relief cap is to hook it up. If you use the fill cap location and build the required psi the pressure relief cap will let it out if it's working right and you won't get accurate results.

 

Have your coolant pressure tested. A bad head gasket should build pressure in tank to above 15 lbs in less than 30 seconds. As mentooned earlier check compressor first. Its cheap and easy.
And yes, i had same thing happed on a 14 liter detroit. Good luck

 

Did you ever find the problem?