Hi all. First post. Thanks for having the forum! Lots of good info.
I have a question with which I hoped someone could help. 1997 Concours. New car for me. Many thanks to the dealer for full disclosure!!! It runs around town just fine all day, but it overheats on hills at interstate speeds. It MOST LIKELY has compromised head gaskets. Everything SEEMS to flow well. Stat/cap are new. Haven't had time to test for gases or look at water pump yet.
So I'm a glutton for punishment and decided to drive it from Arkansas to Cincinnati. Eventually I figure out that it is MUCH less prone to overheating if run in "3" instead of "D", even though RPM much higher. That seemed odd to me. I just rationalized it with the gasket issue by assuming pump more efficient and pushing combustion gases through purge line at a higher rate. The vapor then venting without issue until too much hill stress creates a huge bubble at the pump causing cavitation (when the gauge "runs for the red" the heater stops blowing hot).
Is that a valid assumption? I'd love to find out that the water pump is just crapping out. That thing ran like a champ up to 70 in "3" all through flat Indiana/Illinois, and even cranked up to 80 as I "roller-coastered" the Missouri hills. I had cruise set on 65 in "3" for hours at a time on the flats.
Anyhoo, I was curious about that oddity and thought I'd ask the experts why a compromised head gasket would be LESS finicky at higher RPM's. Thanks for any answers!!
ps- Also, best strategy for pulling temp back was crank heater, slow to ~30 and shift into 2nd. This seemed to bring it back pretty efficiently and prevent the need to stop.