I'm the original owner of an 89 SC with ~90,000 miles and original head gaskets. I have noticed that I'm getting unburned carbon in the coolant overflow tank that's coating the inside - also collects on the radiator cap. However, I notice no exhaust gas bubbles in the coolant or coolant in the oil which would be typical for a blown HG. There is some consumption of coolant which is steadily getting worse the past few thousand miles- no external leaks.
Is this a definite sign of a impending HG failure? Note that I had the supercharger top off recently and noticed some unburned carbon and oil in the housing which was probably coming from the PCV system. Gas mileage is bad currently which probably contributes to the carbon. Have replaced both O2 sensors and tested the coolant and ACT sensors. Checked the fuel press regulator for leakage into vacuum line. Can't seem to find reason for why gas mileage has dropped recently from 19-20 avg to 13-14 but the car is running rich even though the engine idles smooth (although low manifold vacuum at Denver's elevation) and I have plenty of power...
Any help is appreciated - I would like to keep this car in my garage and on the road.
Is this a definite sign of a impending HG failure? Note that I had the supercharger top off recently and noticed some unburned carbon and oil in the housing which was probably coming from the PCV system. Gas mileage is bad currently which probably contributes to the carbon. Have replaced both O2 sensors and tested the coolant and ACT sensors. Checked the fuel press regulator for leakage into vacuum line. Can't seem to find reason for why gas mileage has dropped recently from 19-20 avg to 13-14 but the car is running rich even though the engine idles smooth (although low manifold vacuum at Denver's elevation) and I have plenty of power...
Any help is appreciated - I would like to keep this car in my garage and on the road.