Impeller change

To me it depends somewhat on the turbidity and suspended particulates in the water where you run. I put a little more than that amount of hours on my 50 each year and I waited till the second year to change it. They are pretty durable. But if you ever had a plugged water intake for a short period or ran in some really shallow sandy water I would probably do it for peace of mind.
 
I recently changed the impellar in my 50 Mercury which is a 2003 model and probably has 500 hours on it. I did it as preventative maintenance as I wasn't having any trouble with it. I was surprised to find it looked almost new and I run in a lot of shallow sandy water. I think the modern materials impellars are made of today are far superior to what they were years ago. One OB mechanic told me one of the reasons for changing the impellar every other season is to insure the bolts on the lower unit don't get froze and to lube them well when reinstalling to prevent future problems.
 
Agreed Marvin, sounds like the best reason. I ran a 35 merc for over 20 years and changed the impeller myself, probably three times. I know, not much for maintenance, but the times I did change it it didn't show much wear. The only wear problem I have ever had was the impeller housing on a Yanmar diesel. The impellar can be perfectly fine but if the housing is scored where it contacts the back of the impellar it won't pump adequate water.
 
Considering the issue of machine screws/bolts freezing up:

1. I assume the issue is much worse for motors used in salt water than those used in fresh water.

and

2. I wonder if one of the silicone based greases like SuperLube might do a better job of protecting the threads on the bolts and shaft housing than petroleum based greases?

Anybody hazard a guess?

Larry H?

Gary Johnson?

anyone else?
 
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