Impeller for Early Yamaha

[benchrascal]

I was given an early Yamaha the other day ,a P45 2hp which is supposed to be the late 60’s early 70’s model .Yamaha gets very vague on the years before the 1980’s I did a total service and it runs like a top but it will not pump water no matter what I do .The power head is clear and sparkling clean and the impeller is new ,housing good ,no obstructions .The impeller was changed before I got it and I’m not quite sure how it’s done on this particular model but I can access the impeller and it is pliable and seems to be doing it’s job,any ideas.

[Mumbles]

Are you sure the impeller drive pin or key is OK?

[benchrascal]

The impeller drive pin is driving well ,the boss of the impeller is perfect but still no water.I’m wondering if the impeller is too "soft" to push water but I remember these little Japanese motors all seem to use the same "all rubber " construction.

[billw]

If it were me, I’d pull the lower unit off, find a suitable piece of tubing long enough to simulate head pressure to the top of the power head, and see if the pump will pump water to the top of the tubing, when driving the drive shaft by a drill motor, in a bucket of water. I’m sure there was a better way to word that. Anyway, if the water does make it that far, I’d then start looking for a problem from the lower end, up. Could it be as simple as the motor’s water tube not being into the lower unit grommet correctly?

Long live American manufacturing!

[phil]

Check out http://www.oddjobmotors.com
He has an earlier sixties Yamaha, I’m pretty sure if you drop an email at his site he will be glad to answer your questions. He is an AOMCI member Art S.

http://www.omc-boats.org
http://www.aerocraft-boats.org

[benchrascal]

I’ve already proofed out the top end and the water flows through ,also I’ve driven the lower unit with a drill and with everything sealed up tight and the new impeller there is little or no water being pumped out the grommet and there lies the rub .New impeller ,good housing and no water .Is there anyone out there with access to an exploded diagram of the P 45 yamaha lower unit ? That would be a great help ,I’ve looked and can find nothing ,thanks.

[benchrascal]

Looked at this again this morning ,cleaned and resurfaced both sides of the water pump housing ,noticed just a wisp of what could have been an original gasket .No pictures of this anywhere on the net so I’m guessing the gasket was ruined when the po changed the impeller.Used some of my favourite sealer ,created a new grommet and tested it .Pumped like a dream .

[Author]

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