Loss of Water Pressure

[mibowman]

Greetings,
Have 1989 Yamaha Pro V 150hp. Recently I notice that I would loose all water presure when exceeding 4500 rpm. Changed Impeller and PRV. Seemed to fix the water dump issue. New issue: lose of water pressure when on plane. Have strong PEE at idle and perfect pressure at take off. Pressure steadly decreases under way. Would thermostats be next? I also noticed the woodruff key had wear for the impeller.

Thanks for the advice and help.

Brian

 

[robert graham]

Re: Loss of Water Pressure

The thermostat would be the next item to check/replace. I just changed mine and it had a good bit of mineral/corrosion deposits in and around it, possibly causing sticking...Has your thermostat ever been checked or replaced? I know that I tend to forget things like thermostats and pressure control valve as long as "everything is working fine". Mine had been in the motor since I bought it new in 1999 but I'll not wait 13 more years before at least checking it! Good Luck!

 

[99yam40]

Re: Loss of Water Pressure

I also noticed the woodruff key had wear for the impeller.

Not sure what this statement means.

Only things I can think of that would cause loss of water pressure when on plane would be impeller rubber coming loose from collar that keys to shaft( seen that once), sucking exhaust into the water pump( bad/corroded damper), or something disturbing the water before it hits the water intake allowing air into the pump.
Have you added anything to hull or changed motor height?

 

[mibowman]

Re: Loss of Water Pressure

Thanks for the responses,

Nothing has changed to the set up since the jack plate was installed(long time ago)