What would cause the starboard manifold to be hotter than the port. The port one I can touch forever but the starboard one is close to too hit to touch. Temp gauge reads 140. I replaced the raw water impeller and raw water belt. No improvement. Removed thermostat no difference. A circulating pump can't quit working right? Its just a metal impeller that spins true? 1986 raw water cooled fresh water lake Erie boat. The impeller I replaced had all its fins.