There are a ton of good replies and I appreciate all of them. To my knowledge, the cap is original to the car. Oil looks normal and the head gasket was recently replaced. The water pump has always looked a bit crusty, but the gasket is still holding strong. Only a passing thought, though. I never gave the pump serious consideration until now. Shade tree mechanic in training, here. Getting a pressure test may be my first try; putt putting around town is still safe and practical so I may just run by the radiator shop and see if they can check it out. My next step may be taking it out, replacing the water pump (again, it’s looking rough from the exterior) and flushing it with vinegar. I’ve heard from some friends that may be worth a shot. From there, if there’s no luck, I may double check the head gasket. If that is no use, I’ll see about upgrading the rad and perhaps repairing the old. What do we think?
