Yanmar YSM 12 impeller change

[davidbfox]

Never changed an impeller before, so forgive a blindingly obvious question: is it best to replace the impeller with the pump in place, or first remove the pump? The picture with the new impeller shows someone holding the whole pump in their hand and using a puller.

With pump in situ there is very little room between pump cover plate and starter motor on my engine - enough to get a stubby screwdriver in to undo cover screws but not enough I think for any sort of puller.

So - do you need a puller in practice? Or can you wiggle the impeller off leaving the pump in place?

Any lastly, new impeller has a tiny steel screw across the radius where the shaft would go. Would you expect this to need to be removed and refixed (needing tiny allen key) as part of the installation? Or is it there some sort of split in the shaft that this screw keys into?

Advice gratefully received!

 

[Aja]

Take the pump off the engine. You can leave the inlet/outlet pipes in place and just twist the pump body towards you.

In lieu of a puller either long pointed pliers or judicious use of a screwdriver should be enough to prise the old impeller out. Be careful not to scratch the inside face of the pump body.

The pin should be left in situ. It fits into a key on the shaft as you rightly describe.

All from memory btw as I had this engine a long time ago.

Regards

Donald

 

[sailorman]

you can remove the front cover plate only ( no need at all to remove pump )
carefully remove impellor as stated , fit new impellor & replace cover, (you might need to replace the gasket but not always) smeer the gasket / cover plate with goo preferably Hylomar ( blue stuff ) its very clean to use & better than the horrid red rubbish

the impellor is a jabsco / johnson part

 

[Spuddy]

I struggled with my 1GM - my hands are like sausages and couldn't get that screw to engage.
Solution was to buy a Speedseal replacement cover plate which makes it a doddle and to get somebody with skinnier fingers and patience to put in the Speedseal screw ( a once and for all operation ).
There's a type of pliers called gas pliers which can be adjusted to have jaws parallel - ideal for hoiking impeller out.

 

[simon_sluggett]

As you say the removable face plate on the YSM12 pump is on the back, facing the starter motor. Not the best of set ups for removing and replacing the impellor in an emergency situation. A speedseal adaptor plate doesnt help much as the access is still poor to undo the thumb screw and get at the impellor. I always remove the pump to fit a new impellor, something I do every season anyway as a precautionary measure. A decent raw water strainer is also a must when the pump is this awkward The impellor should just ease of the shaft without too much problem. I smear a little grease to aid fitting the new one. Make sure you fit it in accordance with the correct direction of rotation. Put some gease in the bolts holding the pump on so they dont seize up over time,just in case you ever need to remove the pump in an emergency. I had considered replacing the pump altogether with one facing the other way but havent found a pump suitable yet.