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I have an 89 Yamaha 40 h.p. outboard that needs the impeller replaced. I removed the 4 bolts which appear to hold the lower unit but it won't budge. What is the procedure for removing the lower unit to access the impeller? I appreciate any help. Thanks.
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I think there is five bolts... # 5 is holding the trim tab on by the prop (remove rubber plug above tab to access bolt ) -
jeff,
On my 2000 Yamaha 115 there is an extra bolt under the trim tab - it is separate from the bolt that holds the trim tab. You really need a Yamaha shop manual for your model - go to www.yamahapubs.com and they will deliver to your door. Get your water pump kit at boats.net - good service and good price.
Good luck,
Ken KComment
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You guys were correct. There was another bolt under the trim tab. I also had to disconnect the shift mechanism which was easily done. The lower unit came down with no problem. A lot of gunk and grit in there. The impeller goes into the housing really tight and the blades become curved. Am I correct in assuming this is what's supposed to happen and the blades will bend in the opposite direction when shifted into reverse? Also, while it's apart I plan on flushing the unit with water. Is there anything else I should do? Thanks again for everyones help. JeffComment
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The impeller only turns in one direction, it does not turn backwards when the engine is in reverse. Make sure you bend the blades the same direction of engine rotation.
I would also suggest you use some Sil-Glyde rubber lubricant on the impeller when installing it. Sil-Glyde is a silicon rubber lubricant (silicon grease). You can get Sil-Glyde at NAPA.
You can put additional Sil-Glyde on the backside of the impeller blades to help keep the water pump lubricated.
I have used it for years and have never had a problem with my water pump or cooling system.Comment
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jeff,
Be sure and use a bolt thread sealer where indicated in the manual (lower unit and water pump and trim tab bolts). The Yamaha shop manual calls for Loctite 572, but it is hard to find in small quantities. I use Permatex 14A Thread Sealer with Teflon - found it at a local hardware store in small tube for around four bucks - smells great, too!
Also, torque all bolts per spec in manual. And put a little marine grease on the splines of the drive shaft (as well as the impeller). Make sure the remote gear shift is in neutral as well as the shift rod of the lower unit when you reassemble - best to have two people to stab the lower unit - one to hold the lower unit in place, and another down at eye level to align everything up - first, the speedo tube goes thru the upper casing hole, then align the gear shift rod and the water pump tube, and keep your fingers out of the way that last inch so you don't get pinched.
Good luck,
Ken KComment
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