Posts: 3480
Location: Elk River, Minnesota | Hiya!!
The main rule that many follow is about every 3 years, depending on use. I have seen impellers that failed within 5 years of use, and others (like a previous post had stated) go years without replacement. On my father's 1973 Johnson 20hp, it never had an impeller change until I converted it to a long shaft motor for him back in 2008 or so. It was still in great shape, and still had original paint residue on it from when the lower unit was painted in 1973.
The big issue with the impeller is that after years of use, it will dry out and lose flexibility. When this happens, the fins will have a "memory" so to speak...it will be very evident when the impeller is pulled out. When this has happened, there is always a chance that the impeller will not maintain a tight seal against the walls of the impeller, and this reduces the pressure within your cooling system...not a good thing to have, especially if the impeller fails entirely. That can lead to more issues, like a clogged system. If it clogs and that clog happens before the heads on your motor, your motor will be fried in short order.
At a minimum, I would suggest a 3 year plan...
Steve |
