Notch in impellor

[Malcolm3]

Can anyone say what this notch on the impeller is for and should it be inside or outside when mounted

 

[Daydream believer]

Irrelevant really because 2 of the vanes are cracked & it needs chucking.

 

[Malcolm3]

Sorry just Using an old one to photo. There is only a notch on one side. So issue is should it be in The way or out

 

[Clancy Moped]

I'm not trying to be glib but you note which way it came out?

 

[lustyd]

The vanes are clearly bent in the direction they should be so you can use this to work out which way it came out based on the new one after it's been spinning and oriented itself. A short run won't do any harm either way if you put the lube in and there's water.

 

[Malcolm3]

Thanks lustyd. I did insert the new one as you suggested but that does presuppose it was in correctly before
Think there must be some reason for it

 

[penfold]

I'm struggling to see that it serves any purpose as the hub area is wet anyway. The only thing that occurs is that without the notch an airbubble might be retained at the hub and this could result in the lip seal not being cooled properly and wearing prematurely.

 

[Malcolm3]

That’s what I think too Penfold. In which case it may matter that the notch is facing the lip seal to prevent excess wear. Oddly I’d never noticed the notch before and don’t remember it ever being mentioned either but it may matter. It’s much easier replacing impellers than the lip seals. Thanks .

 

[jon711]

It is just a result of the rubber moulding process, it does not matter how it is installed..

 

[Billjratt]

I checked the impellor on a volvo recently and it had similar notches on each end. I think it's to wet-lubricate the shaft seal and in my case doesn't matter which way it goes in. The vanes will self-adjust anyway, and may "flip" if the engine falls back on compression when it stops.

 

[Boater Sam]

Its certainly a weep to maintain lubrication on the water seal on the shaft. It also acts as an escape route for any trapped/released air which could cause the seal to run dry.