I also have a 150 Yamaha 2-stroke. Last fall I went to my local Yamaha dealer for a price on
replacing my waterpump. They said they do not replace just waterpump components. They
said If I wanted them to do the job, they would have to replace the waterpump, thermostats,
popit valve, and run a complete diagnostic test of the engine. The cost estimate was $400.
plus additional costs for any other problems found. The point I'm trying to make is that it
does seem that some dealers will only work this way; they want the whole job or nothing.

I wasn't prepared to spend that much money so I decided to do the job myself. I replaced
the waterpump components with Sierra brand parts for about $42. and the thermostats I had to buy from Yamaha for about $30. each. I didn't replace anything in the popit valve; just took
it apart and cleaned the parts and put it back together. So far, everything is working fine.

Working on outboards is new to me, and there was a fair amount of labor involved, but I,m
glad I did it as I have gained valuable experience and knowledge as to how outboards work.