Spare Impeller shelf life?

[willk]

I keep a spare impeller in my box of bits - I'm kinda curious as to how long it will remain "good" for. Any of you ex-Barrus lads or others have any ideas?

I've just had the impeller on the V8 pulled after three years - it was still in top shape with very little "memory" on the vanes - we changed it of course but now I'm thinking I should have had the spare fitted and the new one held back - too late now!!

[jeffstevens763@g]

Kept cool and in the dark will see you out willk I would say but a spare is always good to have IMO

Think how long the rubber lasts in suspension units last not sure of the shore hardness of each as a comparison

[Pikey Dave]

Originally Posted by jeffstevens763@g

Kept cool and in the dark will see you out willk I would say but a spare is always good to have IMO

Think how long the rubber lasts in suspension units last not sure of the shore hardness of each as a comparison

Rubber tends to last longer in use than in storage. Brand new tyres are scrap after 5 years on the shelf, tyres in use are good for 10 years (assuming they haven't worn out)

[jeffstevens763@g]

So many grades of rubber though Dave we have gate seals that last for ever just on the shelf and stop logs left on site not covered up I guess for willk it's if their cheep enough carry a spare and replace periodically when engine serviced so you have a new one all the time. I kept my old impellers for over six years and we're still ok they have to be made of good stuff to perform as they do.

[jwalker]

A good question willk and I guess the answer is you can't know. Like you I use a fresh one when I change it and keep a spare just in case I wreck it, on the basis that it'll likely be ok to get me outa the shit in needed. I would press the blades hard down to check for any signs of perishing before fitting.

On a positive note, I've never had one fail in use, only ones with a set and scored edges to the blades after fair use. Except once when I started the engine with the pump full of ice! Fortunately Volvo Penta knew there were idiots about and provided a fail safe drive for the impeller.

What I have had, though, is dried out, inflexible seals in the rear of the pump. An easy and cheap fix after removing the pump. I always use plenty of red rubber grease on any rubbery component subject to wear and have never had subsequent failures. Also, if a seal is single lip and you can find a double lip version, fill the space between the lips with water resistant grease. I've found it's often possible to get a double lip seal just a fraction wider than the standard one and have it fit satisfactorily. As an example of this principle, I had a front crankshaft seal begin to weep early in the engine's life, I managed to get two slightly narrower ones and squeeze them both into the front cover recess with grease packing the space between them - that was more than ten years ago and all is still fine.

[willk]

Cheers lads - plenty of food for thought there!