Volvo overheat

Overheating Volvo My.o2 cents 1. First thing I would do is check the sea water pump impeller. A brand new impeller could be damaged in just a few minutes without water. Maybe a plastic bag got stuck on the intake? 2. Where did the pieces of the old damaged impeller go? They maybe trapped behind the thermostat (I assume your engine has one). I had an impeller that burned up and 60% of the rubber went into the water jackets and 40% "fell into" the intake side of the sea water pump. I didn't see these pieces that "fell into" the 90 degree hose on the intake side. I removed the thermostat and reversed flushed all the rubber from the engine. I thought I was good to go. The engine overheated at higher rpm. Cooled great at lower RPM. I took the heads off, new impeller again. This drove me nuts. The rubber would suck up against the intake at higher RPM and drop away when idling. I lucked out and found the problem. 3. Vinegar soak and flush. Maybe someone like Joe might recommend how long to leave the Vinegar in the engine? I left it in for a couple hours? I did notice a lot of rust. 4. It wouldn't hurt to test your thermostat. Throw it in hot water. Use a turkey temperature gauge? 5. I created a fresh water flushing system, after each trip I would use my onboard fresh water to flush out the salt water from the engine. This was a pain, but it made me feel better. There are lots of flushing systems.