# Impellor/water pump question



## ranno (Apr 7, 2012)

I have a question regarding a water pump impeller replacement. I have a 2002, mercury 60 hp, 2 stroke. I purchased the complete water pump kit (46-812966A11)The mechanic I hired said re-placing the plastic/nylon washers(part # 12-858234) above and below the new impeller was not necessary.My thought is if it came with the kit and they were on the previous impeller then it should have been done.Any thoughts or comments regarding the importance of these washers would be appreciated.Will it hurt the engine or shorten the life of the impeller if they are not placed there or can I do without these two washers as the mechanic said ?


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## anytide (Jul 30, 2009)

you said "it should have been done"....... you mean he did not use them ?


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## ranno (Apr 7, 2012)

You are correct,he did not use the washers. The impeller has direct contact with the face plate on the bottom and water pump housing above.


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## anytide (Jul 30, 2009)

doesnt make sense to me, if it came with the kit and your already in there....


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## ranno (Apr 7, 2012)

Agreed and this is why I am asking the question : Since he did not use the nylon washers in the kit, and the impeller has direct contact with the face plate and water pump housing will this shorten the life of the impeller or hurt the engine performance ?


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## anytide (Jul 30, 2009)

ranno said:


> Agreed and this is why I am asking the question : Since he did not use the nylon washers in the kit, and the impeller has direct contact with the face plate and water pump housing will this shorten the life of the impeller or hurt the engine performance ?


i dont know - not a mechanic.
but i would have used them. 

someone with more exp will post up to this thread.


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## DuckNut (Apr 3, 2009)

The bushings take up the space between the impeller and the plate. They are designed to keep the impeller down and to prevent it from sliding up the shaft. If there is space between the housing and the impeller it will cause aeration and decrease the amount of water being pumped through the system.

If it were mine that mechanic would not touch it again, but his supervisor would be making the fix.

Btw... I am not a marine mechanic, but I deal with pumps all day, everyday.


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## HaMm3r (Dec 11, 2006)

Ah, maybe they were just extra, like when you buy a bookshelf at Ikea and find all those "extra" screws and bolts left over after assembly. Never mind that the thing wobbles like a weeble and collapses a year later.


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## Whiskey Angler (Mar 20, 2015)

DuckNut said:


> The bushings take up the space between the impeller and the plate. They are designed to keep the impeller down and to prevent it from sliding up the shaft. If there is space between the housing and the impeller it will cause aeration and decrease the amount of water being pumped through the system.
> 
> If it were mine that mechanic would not touch it again, but his supervisor would be making the fix.
> 
> Btw... I am not a marine mechanic, but I deal with pumps all day, everyday.


I agree. Most of the time, if a bushing/spacer/shim is provided, it is because a small adjustment in position can make a large difference in performance. I doubt Mercury's brain-trust would have incorporated the bushings into the design if they did not serve a useful purpose.


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## Creek Runner (Sep 1, 2011)

Is this a dealership or a back yard mechanic who works on boats? Did he just not use the new ones and put the old ones back in or not use them at all? 

Question do you hear a chatter in the lower unit while in gear at idle now?


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## ranno (Apr 7, 2012)

Thank you for all the responses.The mechanic was a mobile mechanic. I asked him why the parts were included if they weren't specifically for my lower unit. He said ''not to worry about it" . I ended up calling mercury corporate office and I reviewed all the left over parts with the tech I was referred to..The merc tech was pretty shocked.I am assuming this was simply about taking short cuts.
I appreciate all the feed back from everyone on the forum.


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## DuckNut (Apr 3, 2009)

In many cases "mobile" means "once he gets your money he is gone"

Don't find your mechanic on craigslist.


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## Inshorefisherman (Aug 21, 2015)

I can vouch for this, mobile mechanics suck! Paid one $380 to adjust carbs and troubleshoot problem. Says he fixed it, get it on the water and it's not only worse than before, it began dying every time it went in and out of gear. Pay the money and put it in a liscenced shop. Just my 0.02


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