Impeller

[The Incredible Hull]

So from reading all sorts of forums, everyone seems to recommend changing the impeller\water pump, once every 12months. Apparently the impeller can be become brittle, and perhaps fail\break over 12 months, hence the recommendation.

I then spoke to a couple of friends and cousins etc, who own have owned boats for over 10 years, none of them have heard of changing the impeller so frequently. In fact, one of them has had the impeller in his boat for well over 6 years, and water is still pumping strong out.

Has anyone, actually had a personal experience, where their impeller has failed? If so, please include details on how old it was etc.

Cheers!

[a boat]

So from reading all sorts of forums, everyone seems to recommend changing the impeller\water pump, once every 12months. Apparently the impeller can be become brittle, and perhaps fail\break over 12 months, hence the recommendation.

I then spoke to a couple of friends and cousins etc, who own have owned boats for over 10 years, none of them have heard of changing the impeller so frequently. In fact, one of them has had the impeller in his boat for well over 6 years, and water is still pumping strong out.

Has anyone, actually had a personal experience, where their impeller has failed? If so, please include details on how old it was etc.

Cheers!

Hi, most outboard manufacturers recommend that time frame because they and their dealers make alot of money in spare parts and services. As for if it is needed that is impossible to tell because I have seen less than 12 month impeller shot while some impellers look fine after 10 years. Personally if you are the average user and do about 30-50 hours per year and do not run aground and suck up alot of sand/mud than doing the impeller every 2-3 years is a good practice. Of course with any brand (they are all basically the same below the powerhead) if you do hit a sand bar you should get them checked.

At the end of the day it is your engine so your call and trust me if any impeller decided to completly fail when up on the plane (no matter if you have an overheat alram and SAFE like most modern engines do) than you will have done damage to the powerhead becasue it will get that hot that quick so your mates, with impellers getting onto 6 years are taking a risk. People say here all the time, oh the tell tale is strong so I will wait till it gets weak but rarely does it happen that way and an impeller tends to just fail or some people like to start and run their outboards on the ramp-I saw it just now down at Parsley Bay, a gentleman decided to start his outboard before putting it in the water and he ran it for at about 2 minutes so I can guarentee you he has done damage to his water pump. Any impeller will melt without water even for a very short time.

Cheers,

Huey.

[The Incredible Hull]

Thanks Huey, best explanation I've had so far and does make a lot of sense.

Yes I have also seen a lot of people at Brooklyn, who would start their motors to "warm it up" before putting it into the water.

Another quick one. Can anyone assist in how I disconnect the gear lever, if I was to remove the lower leg.

I have attached 2 pictures below from my 2004 Mercury 40hp.

This is in neutral:

This is in Forward gear:

I think I am some how meant to disconnect it from here before I take off the lower leg, but I can't see anything resembling a bolt or nut. Can anyone point me in the right direction?

Cheers.

[zmk1962]

I run a 200HP EFI Merc and 15HP 4st Mariner as my Aux (and offshore trolling motor - low fuel consumption and no smoke).

I change the impellers every 12-18mths. On the 200HP I notice that as the impeller gets to the 12mth age, the Merc runs hotter in the 2200-2800rpm range but is fine at idle or above 3000rpm.

I don't have a temp gauge on the 15HP but do watch the tell tale as my indicator - but I am lees reliant on this motor than the 200HP and it gets less use than the 200HP so I tend to stretch impeller changes out to the 18mths.

One thing I will mention, in the years I have owned outboards (since 1990s), I noticed one thing that really affects impellers is LACK of use. If you look at the design of the impeller, it is a synthetic compound, with blades(impellers) and it sits off-centre in the housing. Some of the blades are bent in this position. I find that if I do not kick my motors over and run them at least once every month that the impellers wear out sooner. I think the synthetic compound remembers the bent position and the blades become less springy and hence less efficient.

This could explain why folks get such a varied life span out of them - frequent use in clean water is good for the impeller. Regardless, I would not be relying on a 6yr old impeller. Compounds break down overtime - and the manufacturers do not make them to last that long. This is a critical mechanical part in the motor that I just expect to wear and hence plan to change.

[a boat]

Thanks Huey, best explanation I've had so far and does make a lot of sense.

Yes I have also seen a lot of people at Brooklyn, who would start their motors to "warm it up" before putting it into the water.

Another quick one. Can anyone assist in how I disconnect the gear lever, if I was to remove the lower leg.

I have attached 2 pictures below from my 2004 Mercury 40hp.

This is in neutral:

This is in Forward gear:

I think I am some how meant to disconnect it from here before I take off the lower leg, but I can't see anything resembling a bolt or nut. Can anyone point me in the right direction?

Cheers.

Hi, no problem and that your engine is an easy one to do the water pump. Just knock out one of those roll pins and then the lower shift shaft will come away with the gearcase.

Cheers,

Huey.