when to change impeller

[Zuumer]

There are two different types of impellers. The one for the Alpha drive is in the lower unit and is identical to the outboards. This should be changed at least every two years with moderate use or once a year for heavy use. Make sure you install the whole kit rather than just the impeller. The kit has a metal rub plate that replaces the installed one which will more than likely have a groove worn in it resulting in a loss of water pressure. It's kinda like changing a clutch...while it's apart change the throw-out bearing.
The Bravo drive has no internal impeller but rather a belt driven pump on the front of the engine on the lower starboard side. This impeller should be changed when "a decrease in water pressure is noted" according to Mercury. If you're pumping good water and the engine temp is within normal limits...you should be good to go. However, if the boat sits for long periods of time, the impeller on either the Alpha or the Bravo pumps will "take a set" and not push as much water as with a new one.
As with all of our boating stuff...if you have a doubt..change it. It's cheap insurance.

[lovemyultra]

Thanks for the help it was no big deal to change and only around 65 bucks THANKS AGAIN

[Fat Chance]

Thanks for clear'n that up Zuumer.
[ April 22, 2003, 10:11 PM: Message edited by: Fat Chance ]

[Zuumer]

Fat Chance:
Thanks for clear'n that up Zuumer. Glad to help