1969 evinrude overheating at high rpm

[alschrimpf]

i replaced the water pump and works at low rpm but doesn't work at all at high rpm. there is no thermostat what else could be problem.

[russeller]

what kind of motor ?

[alschrimpf]

[alschrimpf]

1969 33 hp evinrude

[Paul Moir]

Did you replace the whole water pump, or just the impeller?Is there a chance that exhaust is getting under the base of the water pump and into the cooling system? Or perhaps through a crack in the casting along the aft end of the 'tower' on which the water pump sits, letting exhaust in that way?Did you use sealant between the impeller wear plate (stainless) and the exhaust housing? Was the pump and impeller the same as the one you switched out?Since reving the engine up in neutral is a quick way of destroying it, I assume you're testing this on the boat at speed. Where is the anti-ventilation (cavitation) plate relitive to the bottom of the boat? 1 or 2 inches below it?How did it work before you changed the waterpump?Please forgive all the questions!

[Namcali]

Just make sure hoses are not clogged.Nam

[Dhadley]

I seen several of those that would overheat without the t-stat. The water dumped so fast it didnt fill/cool the block.

[Paul Moir]

This engine didn't come with a t-stat and there's no place for it - it's the same basic block and head as a '56 30hp to my understanding. It's the last big one that didn't.

[Namcali]

Oh, by the way, how do you know it's overheating?Thanks,Nam