upside down impeller installations

[johnyrude200]

In the last week I’ve pulled apart a couple of the 20-25-28-30-35hp gearcases for motor rehabs, only to find that someone installed the impeller upside down so that in order to remove it, you have to pull the driveshaft. In the several hundred motors I’ve worked on, I have not seen this before.

They are the type of impellers with the wedge type impeller key, with the impeller itself having a lip on one side to only allow it to be installed in one direction. Although come to think of it with the driveshaft recess (not orifice), I guess this is a trick someone could use to reverse a weak impeller (NOT something I would ever recommend!).

Have I been installing these things wrong or are these just some random coincidence situations I have here?

[1946zephyr]

All the impellers I have seen, you don’t need to remove the drive shaft at all. Just slip off the housing, then the impeller. I guess I’m a little confused here
Of course, removing the drive shaft is no big deal, because the pinion gear stays put in that kind of lower unit. It won’t rattle around loose, like the smaller gear cases.

[jeff-register]

Try a Mercury Mark 28 early model motor. Pull the powerhead to get at the impeller or a Scott Atwater with two impellers for one motor. Then we can speak of "different" installations! If you still have your patiences!

[1946zephyr]

Yea, I have a 7.5 Scott to do yet. LOL

[PugetSoundBoater]

You have been installing the impeller correctly. Just a coincedence that you’ve got a couple backwards installed recently. Hard to figure how and why somebody did that,evidently not quite idiotproof

"Some people want to know how a watch works, others just want to know what time it is"
Robbie Robertson

[1946zephyr]

Would someone be so kind as to post a picture of this impeller style in question? I thought all these had a pin in the drive shaft and a slot in the impeller.

[chris-p]

On the newer model Zeph, the slot does not go all the way through the hub of the impeller, only say 80% of the way to pick a number. So the impeller cannot slide right through and past the pin/key.

I always drop them down from the top, but not sure it really matters either way.

[PugetSoundBoater]

I looked up the install diagrams in my 1989 9.9-30 hp. Factory repair manual The leading sharp edge of the impeller drive cam(plastic wedge) goes in the direction of the driveshaft rotation. PM me your e mail and I can send you a photo of the diagrams and text from the manual. You could install the impeller upside down but the drive wedge would also have to be upside down.

"Some people want to know how a watch works, others just want to know what time it is"
Robbie Robertson

[fleetwin]

Well, it sounds like guys got frustrated trying to lower the impeller down over that wedge thing, which can be frustrating, so they decided to flip the impeller, lift the driveshaft slightly, put the wedge in place, then lower it back down into the impeller. It’s hard to know if this would do any damage, might not if the wedge still works correctly and the impeller isn’t forced up/down. I’m thinking you would have seen impeller damage if this was an issue. Nonetheless, this assembly process is incorrect and should not be imitated.
I’m guessing this latest load of gems you have acquired was all serviced by the same technician.

[fleetwin]

Here is the page from svc manual, thanks to Jim (pugetsoundboater)

The manual actually shows pulling the driveshaft out making impeller installation easier. Though the instructions are clear, and correct, it is easy to get confused by terminology and depending on how you are looking at the driveshaft.
This same key design was used on the larger engines as well. Needless to say, you can’t just pull the driveshaft out making impeller/key installation easier.

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