Coolant problem

I recently replaced the radiator in my 2000 volvo. Now my coolant continues to disappear at the rate of 1/2 gallon for every 60 80 miles. Engine is not running hot, but coolant is disappearing, no sign of leaks under car.

1/2 gallon in less than 100 miles is a LOT of coolant to lose, especially without a visible leak.

Please tell us why you needed to replace the radiator. Was the radiator leaking? Was the engine overheating? Was there some other problem?

You’d better test for a bad head gasket. How does your oil look?

I too am wondering what motivated you to replace the radiator. And I too am wondering if this is a bad headgasket.

If it is the headgasket, that much loss makes me suspect a serious gasket breech. Remove your radiator cap, run the engine, and see if there are bubbles coming up out of the fill hole. If there are, chances are that’ll be the combustion gasses blowing through the breech and migrating up and out the fill hole. Confirmation of a blown headgasket can be done via a simple compression leakdown test. Gump in the or contamination in the coolant are also signs of a possible bad headgasket.