Impeller/Water Pump

[LittleSkipper]

Gidday one & all

Could someone with the knowledge and know how tell me how often that small little rubber impeller/water pump buried inside the lower leg has to be replaced? Some years ago I was told every 12 month's as the rubber weakens and cracks over time, or are they manufactured to a standard alot higher now than they used to be so can have a longer service/replacement lifespan. My outboard is an 09 Mercury 75hp.

Regards
Wayne.

[peterbo3]

If you are still under warranty I would get it replaced every year as part of the service schedule if that is required to maintain warranty cover. But in the real world you should be able to get at least two years use provided you run in clean water. If you are in creeks & polishing the skeg on sandbanks then the entire pump housing & impeller may only last six months.
It really depends on how, where & frequency of use. I would still check it yearly though as dropping the lower unit allows the drive shaft to be greased, pump seals checked & bolts treated with anti seize. Plus you need to pull the prop to grease the prop shaft & check the shaft seal & gearbox oil.

[LittleSkipper]

Thanks for the info Guys.

Regards
Wayne.

[Roughasguts]

They can last absolutely years if hardly used and in clean water.
Just monitor there output and steadyness of the stream.

But run in a dry motor! with out water to lube and keep it cool and in around 20 seconds and they melt!!! just as you see some people start there motors on trailers before dunking has to be the worst thing for a dry rubber impellor.

Cheers.

[FNQCairns]

Don't think they have changed any in the last 3 years, they will last 8-10 years but it is solely dependent on the use the engine see's. Mine see's offshore almost exclusively so I have my 5 year old impeller still working quite ok, the pressure has dropped off at lower rpms (read via pressure guage) so I am about to renew. If i dredge some shallow water on the way home at low tide I red flag it in my mind, nothing kills them faster than this, done this to a minor degree twice.

Years ago they where a lot worse, more silicone in them today?? I dunno just that they are more robust.

[LittleSkipper]

Thanks for the info Guys,one last question? That flusher hose that is fitted to new outboards? Does it only circulate water around the engine and not the impeller. I have only used the flusher hose once, as I was told at the Brisbane Boat Show last year this does not circulate water around the impeller and since then I have been using one of those over 200 litre plastic drums (Cut down of course) to drop the lower unit into.

Regards
Wayne.

[BM]

The flush hose attachment directly to the engine block is designed to flush the engine without the engine running.

Far better to run on muffs or in a tank to flush out the waterpump as well as the engine and of course the engine can run up to operating temp on the muffs and flush the engine fully.

Cheers