Expert: chris Wethered - 5/11/2008

Question
what is the procedure for installing a new water pump impeller in my 90's 25 hp yamaha outboard

Answer
Hi Joe,

use your manual if you've got it, but here are some instructions to

follow for replacing the impeller.

Put gear lever in reverse
remove rubber cover on leg
loosen the shift rod connector 3 turns

Remove bolts for gear box housing
clean the anode which is ahead of the rear bolt

Slide gear housing from the leg
once the lower unit starts to move it can be drawn off the leg as the water feed tube, shift rod and drive shaft become disconnected within the leg.

Put the lower unit on a bench
remove the 4 bolts along the support plates
slide the pump housing and impeller up the drive shaft

Remove dowel pin from drive shaft and water pump gasket plus face plate
Replace impeller with new as reassembling
check for corrosion or deposit built up.

Clean beneath the face plate and passages with wire wool. If the face plate is pitted then you should replace it.

gently smear the gasket with grease

Fit the new dowel pin and slid the impeller down the shaft on to the pin

Lightly smear the outside of the pump unit with grease

Refit support plates and fixing bolts.

Best Wishes

Chris