Water pump impeller lifespan

Storyline

Storyline

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On our previous boat I religiously changed the Jabsco water pump impeller every year and never found signs of wear. On Storyline I have changed it once in 5 years and again it looked like new.

How often do people change their's ?
Also, has anyone fitted one of those replacement covers (the ones with the butterfly type screws that are easy to undo/do up by hand) ? If so, any opinions as to whether it was worth it ?
 
I have changed the impeller on TG every spring for 23 years. I have found one damaged in that time. I now have 19 spares (the others I gave away).

I also have a Speedseal. Excellent bit of kit which even if I hadn't needed to check the impeller once in a seaway, gets rid of those awful little screws.
 
tillergirl said:
I have changed the impeller on TG every spring for 23 years. I have found one damaged in that time. I now have 19 spares (the others I gave away).

I also have a Speedseal. Excellent bit of kit which even if I hadn't needed to check the impeller once in a seaway, gets rid of those awful little screws.
Click to expand...
Yes, Speedseal, that is what I was thinking of. Do you still need the paper gasket that is supplied with new impellers ?
 
Water pump failed on my 3YM30 after 500 hours, a known problem

First impeller failed at 42 hours.
Next one got changed with the new water pump at 500 hours
Currently showing 930 hours, but I am going to change it this season. I am expecting the water pump to start leaking again in 1-200 hours.

Personally, I can change an impeller in around 6 minutes, so I am not really that bothered about changing religiously
 
I change every other year. They come out as new.

I suspect it will depend on number of hours use and above all what kind of water you motor in.
I.e. in a muddy canal I would expect them to wear much faster.

It is a spare you should carry - and in an emergency you should be able to change it yourself. However, mine is very difficult to get to if you are any bigger than a midget.
 
Whilst the Speedseal is an intriguing piece of kit I'd rather put its cost to a spare waterpump.

I change impellers when they go, between 500-800 hours running on Johnson pumps and about half that on Jabsco. On the Johnson pumps it's as likely they'll need a rebuild by their 2nd impeller - with Jabsco far less frequently.
Hence the spare pump rather than a Speedseal. The O-ring (on Johnson pumps only) seem to last indefinitely, but the paper gasket on the Jabsco usually needs replacement with each impeller.
 
Not very long without any water supply

Years with a clean water supply




I have seen several knackered ones (blades missing cracks etc ) that that worked effectively and some seemingly faultless that just didn't
However as a professional we never put any back in except brand new as the cost of getting wrong was usually out of proportion to the cost of the impeller
 
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I take mine out over the winter, to let it see the light:D
My pump is easy to get to. It has screws with big knurled heads. If required, I just make a new paper gasket. If it looks OK, last year's impeller goes back in. However, I always carry two spares.
 
charles_reed said:
The O-ring (on Johnson pumps only) seem to last indefinitely, but the paper gasket on the Jabsco usually needs replacement with each impeller.
Click to expand...

I have a Jabsco pump with an O-ring, changed the impeller after seven years, slight wear visible, but then it only runs 50-60 hours a year.
This is on a Beta 20 hp from 2006. (Beta engines mostly have Johnson pumps, which as far as I know use paper gaskets).
 
I change mine after two years. I also take the impeller out over winter while the boat is ashore. There is no visible wear to the impeller but I have found that after that time, the pump has difficulty priming the cooling system at re-launch. The frantic sucking and blowing through pipes, salty water squirting everywhere but where you want it and boatyard hands standing around sucking their teeth is just not worth it!
 
I replace mine every 2years. Still I got caught out, the center bush separated from the rubber fins, resulting in a call for a tow in 52 knots of wind on the nose and a hole in my wallet on the last day in the water. So when you check the impeller look beyond the fins.
 
cid said:
I replace mine every 2years. Still I got caught out, the center bush separated from the rubber fins, resulting in a call for a tow in 52 knots of wind on the nose and a hole in my wallet on the last day in the water. So when you check the impeller look beyond the fins.
Click to expand...

On my Johnson impellers there is a rod which goes from the outer side of the bush through the centre hole and through to the outer side of the bush on the other side. I don't see how the bush could ever turn separately from the fins so I am guessing that yours is a different design. Or does the rod snap or something?

Richard
 
The biggest cause of short impeller life is usually down to installation (followed by suspended solids). Any restriction on the inlet pipe work such as 90 degree elbows, small gauge pipework, fine gauge filters etc.. can cause a cavitation in the pump which will damage the impeller vanes and in severe cases cause a cavitation corrosion in the bronze of the pump internals. Even the engine manufacturers have been known to supply some of the engines with a 90 degree elbow screwed into the pump body. Smooth pipework curves, minimum restictions on the inlet pipework will increase impeller/pump life. Suspended solids come second, basically the pump was designed to pump liquid with suspended solids, and are regularly used in industrial applications for pumping liquids with suspended solids, with little effect to the pump...

Jon
 
I change mine every year.
Not because it's unserviceable but because I don't want to worry about it when out in the briny miles from help.
:-)
 
I change mine every 300 hrs and they tend to show the starting of cracks at the impeller blade roots at this level of use. At 500 hrs they are starting to look distinctly cracked but still intact and work ok. This is a main outboard but seems to be about the same when I had a Yanmar IB.
 
When I had my first Yanmar, there was a tendency for some impellers to fail.
Some failed by the metal centre spinning in the rubber body.
Once, I was on a boat where this happened after we'd fitted the spare.
Fixed by superglue, it allegedly lasted another two years!
I went for the school of thought that if you had a good one it would probably last many years.

Particularly weekend use by someone who'd rather use the sails.
It's good to whip it out twice a year, to be sure it's not corroded to the shaft, but it is possible to damage the impeller removing it.

I think it's well up the list of spares to carry.
300hrs sounds sensible too.
 
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