84 Yamaha -70 horse cooling issue

[oneslikfish]

I am overheating so I installed a new water pump. After that same prob. still overheating checked thermostat its ok. took off cover that is near thermostat to see if water was even getting up there and it does in neutral but does not when put in gear unless at high rpm's. Should I replace the wholewhole water pump houseing and all as I cant find any restrictions in the system the motor runs fine other then this

[boats.net]

You probably should recheck the water pump housing. Did it look melted at top around stainless insert? If it did replace it.

[oneslikfish]

No signs of melting on waterpump houseing. However a very small groove has worn in a circle shape on the mettle plate that the impeller runs on. Would that do it?

[Ken]

slik,
A small wear pattern groove in the impeller plate would not cause your problem - but it is best to replace the plate and cup when you do a water pump repair anyway.
I'm thinking your impeller may be installed backwards - and I'm not trying to insult your intelligence - it's an easy thing to do.
Also, all gaskets and any o-rings associated with the water pump should be replaced.
Also, check the input area leading up to the impeller just below the plate - may be clogged with debris.
Good luck [img]smile.gif[/img] ,
Ken K