Changing Impeller

ghostlymoron

ghostlymoron

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After a bit of a struggle and dropping my glasses into the bilge, I managed to remove the impeller from my water pump. To my surprise it was attached to the shaft as shown in the first picture.

IMGP0365_zps7373054c.jpg


I was expecting just the impeller to come out but it has a screw through it which goes through a hole in the shaft. So obviously it can't be removed from the shaft until both are removed. Previous pumps I've had have had a flat on the shaft (and the impeller) so it just pulls off, leaving the shaft in place as shown on the extract from the manual shown below. You'll have to click on the link.

http://www.keepturningleft.co.uk/wp...images/Mirror-Offshore-U-MD1-manual09_jpg.jpg

Is this right? and do I just have to put a new impeller on the shaft and re-insert it?
 
You can cut a slot on the top of the shaft and use a normal screw attachment.It's not good to disturb the seals so if you can keep the shaft in place,all the better.The illustration shows a normal slotted shaft which indicates that yours is not original.
 
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Just a thought as I'm not expert in pumps, but has someone fitted the shaft the wrong way round? If the other end was on the pump side, an impeller with a central bar would fit neatly into the slot, and presumably whatever is now passing through the slot could instead be screwed into the hole.

Pete
 
prv said:
Just a thought as I'm not expert in pumps, but has someone fitted the shaft the wrong way round? If the other end was on the pump side, an impeller with a central bar would fit neatly into the slot, and presumably whatever is now passing through the slot could instead be screwed into the hole.

Pete
Click to expand...
Ooh err, I hadn't though of that. Perhaps I should take the complete pump off and take a closer look. It's only held on by two bolts so shouldn't be too difficult although doing anything on my engine involves keyhole surgery! I am beginning to see why Dylan got so frustrated with The Beast.
 
30boat said:
You can cut a slot on the top of the shaft and use a normal screw attachment.It's not good to disturb the seals so if you can keep the shaft in place,all the better.The illustration shows a normal slotted shaft which indicates that yours is not original.
Click to expand...
Presume you meant to say 'It's not good to disturb the seals' . Slotting would be good but as prv says there's already a slot at the other end which is not shown well on my photo.
Edit. i see you've now added the 'not'
 
ghostlymoron said:
Presume you meant to say 'It's not good to disturb the seals' . Slotting would be good but as prv says there's already a slot at the other end which is not shown well on my photo.
Edit. i see you've now added the 'not'
Click to expand...

If you look at the parts diagrams, the shaft appears to be slotted at both ends. Maybe you need to investigate what's holding the impeller on to the shaft.
 
This is a picture if the shaft from Keypart's website

Slotted at the drive end, a hole at the impeller end as gm has discovered. Clearly not reversible

Goodness knows if that the original design or not


6902_thmb.jpg
 
VicS said:
Goodness knows if that the original design or not
Click to expand...

Well, it's not what's in Dylan's manual page linked in the OP. But that engine's been around so long that it could well have been changed.

It has at least explained why the impeller I've just bought for my shiny new(ish) Volvo engine has a central bar that screws in and out when the shaft it fits onto has a slot. Obviously that arrangement allows it to fit a wider range of engines.

EDIT: So to answer the original question, it looks like yes, you screw the bar out, fit the new impeller to the shaft and screw the bar in, then insert the whole lot back into the pump.

Pete
 
That's like mine but mine is without the step in the shaft.
VicS said:
This is a picture if the shaft from Keypart's website

Slotted at the drive end, a hole at the impeller end as gm has discovered. Clearly not reversible

Goodness knows if that the original design or not


6902_thmb.jpg
Click to expand...
 
ghostlymoron said:
Presume you meant to say 'It's not good to disturb the seals' . Slotting would be good but as prv says there's already a slot at the other end which is not shown well on my photo.
Edit. i see you've now added the 'not'
Click to expand...

I did type the "not" but when I submited the post it disapeared.It's been happening a lot recently.
 
I have all three types in my spares box. They came with the boat so I have no idea which one is original.
By the way, the shaft in the pic looks to be showing some wear. I had similar wear on mine and when I put it back in it leaked water into the engine resulting in another oil change, and two new (expensive) seals. I would like to get a new shaft as a spare but am afraid to inquire the price.
MD11C by the way.
Capt. RoN
 
ghostlymoron said:
How do you change your impeller ?
Click to expand...
I unscrew the face plate (I have a Speedseal), pull out the impeller and shaft as a unit, then unscrew the set-screw through the impeller and pull it off the shaft. Reassembly is the reverse (as the Haynes Manuals used to say). You have to be careful when replacing the shaft not to damage the two back-to-back rubber seals.
 
Alan d, yes I am concerned about damaging the seals when re-inserting the shaft.
Yours must be a different pump because Speedseal told they didn't do one for a 2½", six hole model.
 
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