Hi, I have a 40hp Mercury outboard that sounds an overheating alarm when revs, get over around 4500 rpm, this outboard is a US made 4 cyl 2 stroke 1996 mod,
first of all this outboard does not have a thermostat by design, so i replaced the impeller but the impeller blades were bent only and not realy damaged in any way so i am concerned that i have not fixed the problem, the engine is in very good condition for its age so i am wondering if any one else out there has had a similar problem with this engine and if so was it resolved and how.
regards Mike.