I'm having a problem with my cooling system. I have a 2003 Volvo S60 2.4t. I pulled into a messed up parking space the other day and cracked my radiator on an elevated parking block. I shut the car off, towed it.. Replaced the radiator, filled it with fluid. Everything looks good, no apparent leaks.. But after it warms up a bit, coolant will leak out of the reservoir cap.. I replaced the cap, still overflowing. Temperature looks good on the dash.. I didn't have this problem before the radiator cracked the other day, and I have no reason to assume that it would have overheated.. Anybody know why it's doing this?

 

First pressure test the cooling system to find and solve any leaks. If you have a leak from the cap - either the cap is bad/reservoir is cracked or too much pressure is being built up in the cooling system. Too much pressure comes from combustion gasses getting into the cooling system from a damaged head gasket or cracked cylinders on some cars. A combustion gas leak detector (borrowed/rented) from your local auto parts store can easily test for that.

 

The system needs to be burped OR bled to remove air. IF your temp gauge is slowly going up and down during driving, it means your head gasket might be bad.