Mercury Mark 20/25 Impeller Installation

[oldoutboardjim]

Any wisdom to impart here? I have a sleeve that is slightly smaller than the pump housing I.D. (pre-forms the impeller), and used super glue to hold the pin in place, but after one try, the pin was at the bottom and the impeller was freewheeling.
Curses, Carl Kiekhaefer! Why did you make this so difficult!

[dave-bernard]

clean up the leading edge of the impeller make it larger so it catches easier but not all the way up the groove. I do it with grease not glue and have no problem.

[jeff-register]

You can use PVC white pipe to compress the blades & slide the impeller straight down. I hear many complaints against Mercury. They require a little innovation & learning curve. I enjoy the challenge & enjoy the performance they have. Try installing rings in a 5 hp Merc pistons in backwards with no way to compress the rings. Plastic Coke bottles & zip ties for compressers, They fell right in place.

[billw]

Make sure it fits easily over the shaft with NO pin, first. It has to be free to move up and down anyway; but fighting the impeller down a rusty shaft complicates the installation about ten fold. Don’t worry. Once you light the candle on that bad boy, you’ll forget about your past problems with it. Have a cigar ready for the full affect. Signed, Carl.

Long live American manufacturing!

[legendre]

quote Jeff Register:

Try installing rings in a 5 hp Merc pistons in backwards with no way to compress the rings. Plastic Coke bottles & zip ties for compressers, They fell right in place.

So in fact, there +is+ a way to compress the rings.. just pointing that out. 😉

BTW, are you referring to the 70s-80s era Mercury 5HP (marked 4.5 or 45), single cylinder, with the one-piece jug & head? I have one of those, and they’re a very nice motor. Only real gripe, is the somewhat poorly engineered reverse lock mechanism. Bad place to cheap-out and use plastic instead of metal.

[jeff-register]

Legondre,
No I am referring to my KF5 motor. The two small pistons installed crown in from the bottom of the bore with no room for my fat fingers & no way to compress the rings made it very hard then stack needles on the rod & journal to get the cap on was quite the trick for this old man. 25 or 26 needles to mike to get ready to install on the rod under the crank was a special treat not picking up already in place frozen grease then to flush it out to get it to start not running gasoline & grease mixture. Gotta be ready for that task in a good mood.
I’m trying to not build anything that includes nylon or plastic in the assembly but becoming harder!

[oldoutboardjim]

Second time was a charm. I used ignition cam grease (sticky), and modified my guide sleeve slightly. It’s all together!
Thanks to everyone for the "guidance" (pun intended). 😆

[jeff-register]

Jim,
The Next one will go real easy now you know the tricks!! 🙂

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