Remove the impeller over the winter?

FlyingDutchman said:
Again, many thanks.
Although the thoughts vary, I think I will take it out and carefully inspect it next year. If it looks immaculate, I will put it back and see what happens. I do carry a spare impeller anyway...
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It isn't just the lack of coolant that concerns me it is where the bits of a broken impellor go if it fails. Even if you carry a spare and are able to fit it in a panic (in heavy weather on a lee shore for example) the broken bits could be downstream in the system causing further problems.

Of course fitting a new impellor doesn't completely eliminate the possibility of a failure but best practice routine maintenance is supposed to reduce, to a minimum, the possibility of an inconvenient failure .
 
Reputable impellers are designed to withstand commercial use all year round use, and are batch tested, either by the original manufacturer [rarely the same as the reputable brand name on the box] or by the reputable re-brander, to ensure far in excess of 1000 hours life.
But many leisure users will not even reach 100 hours/year! and probably at relatively low cruising rpm rather than at the engine manufacturers max continuous rpm.
So if you're a typical yachtie with a small 1-4 cylinder auxilary engine, remove it, clean it in hot water [which will also soften it for inspection], inspect it carefully with naked eye,and if there's any visible damage [bits of blade missing, splits, cracks at the roots of the blades] then throw it away.
Otherwise, dry store it; it will dry out [shrinking back to original size, because all impellers absorb water over time and swell, but not so as to be visible to naked eye], and if the blades have straightened out, and remain pliable and flexible, re-use it with confidence next season. If despite being undamaged, it is stiff and age hardened [like an old pencil rubber], then replace it!
Jabsco have a great visual guide as to what signs of damage to look for, and what you can safely do with your existing impeller go to the end of this link:
http://www.xylemflowcontrol.com/files/artdoc4851.pdf
When you reckon it's done a 1000 hours, consider changing it as a precautionary measure - you'll have had good value from it by then, but it's still worth keeping as a spare for emergencies...
And the lower pressure impellers [fewer, thinner, softer, longer blades] found in many smaller, engines are more more forgiving of dry running than the higher pressure impellers [more, thicker, harder, shorter blades] found in larger higher speed engines.
With small impellers, you're very unlikely to damage the impeller as you pull it out with a pair of pliers or lever it out with a screw driver, but you can all too easily damage the inside of the pump chamber or its edges - which will damage whatever impeller that you put in it next!
 
Must admit I have never touched impellor in seven years of ownership.
However given the nature of the piping I suspect the impellor remains filled with water.
Oh well something I will check tommorow just in case!
 
I've always gone with the advice I was given with my first yacht.
Always have a spare or two on board.
Remove the impeller every year, clean the shaft and metal boss, lightly apply anti-seize, replace.

Otherwise the salt or corrosion may mean the impeller won't come off the shaft easily in a crisis.
Apparently some years ago, there was a dodgy batch of Yanmar impellers where the rubber bit came loose from the metal boss after a few tens of hours. So you were better off with a known good, tried and tested one, until it starts to crack up.
No reason why it should not last 5 years of normal use or even more.
Equally, if it looks suspect, change it.
 
lw395 said:
I've always gone with the advice I was given with my first yacht.
Always have a spare or two on board.
Remove the impeller every year, clean the shaft and metal boss, lightly apply anti-seize, replace.

Otherwise the salt or corrosion may mean the impeller won't come off the shaft easily in a crisis.
Apparently some years ago, there was a dodgy batch of Yanmar impellers where the rubber bit came loose from the metal boss after a few tens of hours. So you were better off with a known good, tried and tested one, until it starts to crack up.
No reason why it should not last 5 years of normal use or even more.
Equally, if it looks suspect, change it.
Click to expand...

You silly boy, THAT is far to sensible :D
 
The impellers seem to be fairly bombproof (500 hours and looks new) but some pump covers suffer from corrosion if the impeller is left in place over the winter. On my Yanmar the cover plate was badly corroded with an impeller pattern when I left it in place over the winter. I can't explain this as the engine had been well flushed with preserving oil and antifreeze.
 
If the boat is lft afloat it is worth remembering that with some Volvo outdrives the impeller should be left in to ensure the engine does not fill with water and the boat sink this could also happen with other installation without seacocks.
Whilst a visual examination is worth while if there is any doubt replace it.
 
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