Lower unit removal and water pump replacement

[Birchbark]

I am still looking to solve my problem with the removal of the lower unit from my 150Hp 4 stroke 2006 yahama engine. I want to inspect the water pump and replace it. I have removed he four bolts and it will not budge. How does the trim rudder come off? The nut looks like it is below the upper unit and is in the lower unit. This has been driving me nuts. I want to purchase parts, but need to see what I need first! My manual is of no use.
Birchbark

[robert graham]

Pry up with a screwdriver and remove that square black plastic piece, remove bolt down in there that holds on the zinc trim tab, remove trim tab, then up in there remove that 5th bolt holding your lower unit on. Good Luck!

[robert graham]

Google: Yamaha Maintenance Tips Andy, for instructions with photos for water pump replacement and several other maintenance/repair procedures...very helpful!

[Birchbark]

Thanks Robert! I tried all of this and I could not get socket around nut in shaft! Seems to be something between nut and housing. I am in the process of cutting the very hard zinc of with drill bits and cutting tool! Once this is off I can get at the 5th bolt.
Thanks

[robert graham]

Sometimes in tight/close quarters may need to grind down circumference of a socket so it fits into area. Sounds like this job is trying to give you a hard time, but keep at it!

[Birchbark]

Thanks Robert, the tip about the the site Yamaha Maintenance was very helpful. Once I had a god understanding of just what I was looking at I knew what I had to do. My last resort was to drill out an area of the zinc so I could get at the last lower unit bolt. Now I have the unit apart. After all of that the water pump looks great, but maybe I should replace it anyways? Now the question is, why was the warning buzzer going off? I had the water muff on and water on.

Thanks Robert,
Do you have any more good suggestions?

[robert graham]

While you have the lower unit off,go ahead and replace the entire water pump(kit about $55), then inspect/replace thermostat and pressure control valve. You'll need to install a new zinc trim fin. Good Luck!

[Birchbark]

Thanks again Robert. Nothing was easy, the impeller would not pry up from the shaft. There was a piece at the top of the impeller (metal) that would not budge, I had to use a hack saw to cut it loose. I hope it was part of the impeller. I am off to the Yamaha dealer today for parts. I hope the impeller has the same metal top piece on it. I am taking you suggestion on purchasing the pump. The do not have the complete unit but they have a complete rebuilding kit including the housing. Thanks for keeping me on the right track.

[robert graham]

That stainless piece you hack-sawed should go on over those 3 spring washers to take the up and down play out of the driveshaft....you pull up on the driveshaft while tapping the piece down, thereby removing the play. better get you a new one and the 3 spring washers to go with your new water pump kit. A 3M scrubber pad and wire brushes are good to clean everything up for re-assembly. I used marine grease on most surfaces including bolt threads to help keep water and corrosion out. Good Luck!

[Birchbark]

You are the man! Thanks again. In looking at the parts catalog at the marine store it shows this part on top of the metal cup. On my water pump this unit was directly on top of the impeller! It looks like this might have been installed wrong from day one? The spring washers and other part had to be ordered. Thanks again. It is amazing just what you can find on Youtube!
Thanks again, I'll keep you posted!