86 pro v 150 still burning up water pumps.

[2mark1965]

Started it up today after the conversion to pre-mix last winter. Cranked right over smooth as silk. Had it on muffs would not pump water. Got alarm, shut it down. Pulled the lower unit, impeller had melted again, clogging up the pump housing. Gonna order factory Yami pump. Hope this does it. Ran pressured air from Intake to pee hole and back the other way. No clogs. I have heard these motors don't like muffs. Cant figure though. How are you supposed to check and service. I am totally confused. Any help appreciated, and feel free to call me a dumb butt. This is my first big boat motor.

[99yam40]

get new kit and housing
make sure you never crank it up without water hooked up.
May need to rig up a tank to run it or find a different set of muffs to give more water

[2mark1965]

Thats kinda what I'm thinking. Eyeing a 50 gallon trash can and thinking how to put a drain in the bottom. The motor runs strong, but it will not pick up on muffs. The impeller just melts and clogs everything. Just ordered a complete Kit from premiere marine out of Fla. Yamaha has discontinued these parts from the factory. Like you said, Think I need to rig up a tank, never had a problem on the water. Thanks for the. Advice.

[99yam40]

housing does not come with kit, has to be ordered seperatly

[2mark1965]

I did also buy the housing with the Kit, complete new water pump and components. I do have a question though. I hooked up a hose straight to the inlet tube where the the actual pump slides on. Had good pee, started engine and after about five minutes got alarm again. Is it because the impeller is not there and not pushing enough water through fast enough? I shut it down when it buzzed. Engine starts first crank, smooth Idle, so I must have got the premix conversion right. Just Curious,do these engines have a thermostat? I live in a rural area and dont have access to good techs. Scratching my head. Thanks.

[madharchod]

mate when you say the water pump melted and clogged up the line i would be opening the exhaust chamber to remove the bits and pieces of debry that is stuck in the beehive water cooler if one piece gets stuck it will cause the alarm on these motors
cheers

[2mark1965]

Everything seems clean. There are 2 seals between the waterpump housing and water tube. Mine didnt have those when I replaced the pump before. Bet I was sucking air which would not allow the pump to" pump" efficiently. Kinda makes sense. Sucking air , not pumping. BTW the water jackets are clean. Compressed air through them. Thanks Brah.

[99yam40]

should have stats on top of each head

[2mark1965]

Yup, found them. Looked pretty cruddy. 2 new ones with gaskets on the way. Gonna back flush through the stat holes. Any other advise while I've got it apart?

[99yam40]

check PRV to make sure it is not sticking open or cruded up like the stats

[jb123]

are you telling us you got a better deal on parts elsewhere? i doubt it....

[2mark1965]

No not at all, ordered what I could from you but it showed the waterpump kit was discontinued.

[2mark1965]

99yam40, Is the PRV there on the back of the engine below the exhaust plate? If so I'll order a new one and gasket from you guys. Better safe than sorry.

[BQUICK]

There is a block off piece between the exhaust housing and water pump. If missing exhaust can get to the water pump.

[2mark1965]

Is that close to the PRV? What would that part # be? If I can replace it I will because I want to go through everything while I have it apart. That would make sense, because I always run double muffs on it before I ever start it, and it seems that something is causing them to melt down. Thanks.