MacGregorSailors.com

Great summary, Mastreb

Obelix

JohnCFI wrote:To sneak in another question, if I run at 3000-3500 RPM or more I get an overheat buzzer after a while, slow down to less that 2750 and it goes away, and will run happily all day. Any suggestions as to cause, someone locally suggested wrong oil type (Tohatsu 50HP don't know exactly but probably only a couple hundred hours up).

What is the motor speed at WOT? It's possible you're overpropped, and lugging the engine at higher speeds. Or there are clogged passages. Or the impeller has lost a lobe or three. Or the thermostat is stuck in a partially open position. Lots of possibilities, but you need to start with the engine being propped correctly for the boat.[/quote]

Thanks for replying. I dont think she gets much above 4000-4500 RPM, but I will need to confirm that next launch, I will have a look at the prop tomorrow and report size etc, be a bugger if its wrong I have a BN spare!!

That was a great synopsis Matt. I'll have a good spring post for you to comment on!
John
I think you'd be really trying hard to trigger an overheat alarm with a mis-matched prop. As previously stated, the problem must lie within the cooling system.
Ross