My V6 Jimmy, 1999, is losing coolant through the overflow tanks overflow tube. After a short drive, the coolant backs up and overflows. I have a new 16 lb radiator cap. I've noticed the coolant is very dark, almost black. It loses approx. 1/2 gallon each time. No other leaks. The oil is clean and clear. What could be causing this?
Tuesday, May 8th, 2007 AT 9:40 PM