How to Install wp impeller

CocoaBear

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Sep 17, 2011
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17
I've asked this earlier this week without any replies, I really could use some help. I have a 1990,40hp Johnson and I have the water pump disassembled and the new parts in hand, but I can't get the key and impeller to go on the shaft together. I've got a M&R Manual for the motor and it says to install the key using grease to hold it in place. I've tried grease, double sided tape and you name it and I can't get the impeller to go over the key in the shaft slot.

What's the secret? I know someone has done this before and I could use any advise.
Thanks
 

lakedweller1

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Apr 3, 2012
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Re: How to Install wp impeller

I just replaced mine on a 65 hp Mercury. I laid it on a table with the flat spot up. Added high-temp marine grease and the keyway stuck just fine. If your lining up the slot with the keyway perfectly, it should slide right on. The only thing that comes to mind is do you have the wrong impeller?? Try to reinstall the old and see if it just slides on. If so, you way have wither the wrong impeller or it may just be a reject and not be made exactly right. Exchange it. If your sure you have the right one, line it up exactly and stick a pipe down the shaft until it rests right on the impeller. VERY GENTLY tap the other end of the pipe with a rubber mallet. The impeller should slide on.
 
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2,906
Re: How to Install wp impeller

is there a lip on the impellor that stops you puting it on upside down? you should be able to dry fit the impellor on the shaft with out the housing to see if it fits first then insert impellor in the housing and it should go (little lube helps so you can turn the impellor to index the key). if it does not fit then you proberly have wrong parts
 

Joe Reeves

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Feb 24, 2002
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13,262
Re: How to Install wp impeller

Hold the impeller housing in your left hand.... have the impeller in your right hand.... insert the impeller into the housing with a counter clockwise motion. Turn the impeller so that you will remember exactly where the key slot is.

Now, facing the driveshaft impeller slot, the impeller key must be attached so that the small curved to nothing edge is facing left. Attach it to the driveshaft with a small bit of some adhesive type gasket compound (OMC Adhesive is now Bombardier 3M Product #847).

Slide the housing and impeller assembly down the driveshaft and carefully have the impeller engage the key. Let us know how you make out.
 

CocoaBear

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Sep 17, 2011
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Re: How to Install wp impeller

Folks, thanks so much for taking the time to reply to my question. The more I use this forum the more it amazes me at the generosity of the people who post and reply to posts to help others. I always put the knowledge I gain to good use. Maybe I can get this thing together and on the water.
Steve
 

Joe Reeves

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Feb 24, 2002
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Re: How to Install wp impeller

We assume you managed to get it installed?
 

CocoaBear

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Sep 17, 2011
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Re: How to Install wp impeller

Adm. Reeves, No I haven't been able to get it together. I tried to reinstall the old one and I compared the keys and the impellers and they are they same. The key is the black plastic one. I tried to use double sided tape, but I'm going to use the adhesive you recommended and see if it has more holding power. You really did bolster my confidence though. I'm not a bad mechanic, and this thing is very frustrating. I really would have preferred a shear pin.
If you can think of anything else, I'm listending.
Thanks again.
Steve
 

daselbee

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Jan 20, 2009
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2,765
Re: How to Install wp impeller

Try this. This is how i do them all.

The trick is....put everything on the driveshaft; gasket, base plate, impeller and key, etc. Lube the impeller with dishwashing soap. Lower the housing onto the impeller. It will not fit ,of course. Then, while pushing down on the housing, rotate the driveshaft clockwise. As you turn the driveshaft, the blades will bend in the correct direction, and the housing will slip into place. You have to push down, kinda finagle it if you follow. Install bolts, and go!
 

Skillz248

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Jul 11, 2011
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19
Re: How to Install wp impeller

Make sure you dont have the impeller upside down. It will only slide over the key one way.
 

CocoaBear

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Sep 17, 2011
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17
Re: How to Install wp impeller

Thanks Folks, I've done I think everything that everyone has suggested. Part of the rubber does block the impeller from being installed upside down and I have tried putting it on using just the impeller and the key as I did to try and reinstall the old one, but couldn't get it done. I thought if I could do it once, surely I could take it off and reinstall permanently. Can you imagine doing this on the water, I'm in a shop with good lighting and a solid footing. I'm about to drill both the impeller and shaft and put a spring pin in to hold it in place, it's driving me crazy. No I wouldn't really do that, but I'd like to. I still have to put the 3M glue on to hold the key in place.
Guess I'll keep trying.
I really do appreciate all the suggestions, they help to make sure I've not forgotten something. Maybe if I stand on my head??
 

daselbee

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Jan 20, 2009
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Re: How to Install wp impeller

Just as incredulous as you are that you cannot get it done, you have to admit that over the many thousands of WP jobs done, all of them must have failed, due to the inability of the mechanic to get it done.

Send it to me, I'll get it done......
 

Silvertip

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Sep 22, 2003
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28,758
Re: How to Install wp impeller

You can try tilting the top of key slightly toward the shaft so it has a chance to engage the slot in the impeller hub. You shouldn't need to do this but you can also use a small file to file a very slight taper on the bottom edge of the impeller groove. That and the slight tilt to the key should allow this thing to slide together. This is sort of like the Kyocera printer commercial "it is really not that difficult".
 

Haffiman

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Dec 17, 2009
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2,454
Re: How to Install wp impeller

If key is too big to fit, 'adjust' it by grinding off some on the flat end with some sand paper or on a flat file. Do not try to grind anything off the impeller hub!!
 

CocoaBear

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Sep 17, 2011
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Re: How to Install wp impeller

Just South of Lake of the Ozarks in Missouri, near a little town, Lebanon.
 
Joined
Feb 17, 2012
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2,906
Re: How to Install wp impeller

time for pictures if thats possible?.......is the wedge the right way round like joe said.........if you can get the wedge back off try the impellor on its own with no key that will count out a badly made impellor or a incorrect model.
 

CocoaBear

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Sep 17, 2011
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Re: How to Install wp impeller

Well folks, with all of your suggestions, I finally was able to get the key and impeller installed. I do have one last question to bother everyone with. After I got the key and the impeller installed there's about a 20 degree rotation of the impeller without the shaft turning, this motion can be back and forth, but tightens up and the shaft turns after the 20 degree rotation is exceeded. Is that normal. To get the key installed I have to remove some of the casting ridges on the rear of the key, just a small amount not more than
.005". I also put a slight chamfer on the top edge just enough to break the sharp edge. Then when I tried to put it on I rotated the shaft and held the impeller and key in position. I put it on and took it off several times just to get the technique down. There is a technique to it if I did it right.

Is it normal for the impeller to rotate on the shaft a small amount before it locks up to the shaft?

Thanks again for all your help. I would never have gotten it together if not for your interest and suggestions.
 

Haffiman

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Dec 17, 2009
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Re: How to Install wp impeller

Yes, it is normal for a play that allows the shaft to rotate before it locks to the key. Next time you want to change impeller, hold it with a vise-grip and counter rotate the shaft and it gets loose.
 

CocoaBear

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Sep 17, 2011
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Re: How to Install wp impeller

I wish there was a way to personally thank everyone for the encouragement, information and interest in helping me solve this problem. I've asked for help on this forum previously and gotten the same great treatment. It is amazing that so many of you want to take your time to help a beginner. I hope someday I can help someone on here as well.
For now all I can say is, Thank You.
 
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