Powerhead to lower unit gasket, 5.5 Johnson

[labrador-guy]

Buster wrote:

Antique Outboard Friends,

As an addendum to this project, I was curious about the water circulation pattern on these engines.  The bulk of the cooling water enters on the throttle side, circulates through the power head and exits on the shifter side.  I did notice a small, machined passage, shown on the attached photo.  This would allow a small amount of the return water to exit into what I’ll call “shaft alley”.

Can anyone tell me the purpose of this feature, as it applies to the water circulation scheme?  I’m continuously impressed by the smart design features of these ’50’s vintage engineers in their products.  Slide rule guys knew their craft.

I too like to follow those drillings  and the cavities to see where they go and why they do what they do!  Some engineer found out an outboard is a lot quieter with the exhaust going out under water.   Another engineer found out that a small exhaust relief port keeps the motor running at low speeds.  Another dude sent some water down the exhaust to cool it and the water came out the exhaust relief so we know the darn thing is cooling itself..  Only took about 50 years to get that far!   One thing for sure they didn’t tell us everything we have to learn it for our-self.  I have found water tubes with holes drilled in them.  Some outboards get black from heat just under the power head, maybe a mechanic did his own engineering.   It sure is fun trying to figure stuff out on these old timers!

dale

[Buster]

Responders,

One additional question.  When I disassembled the old water pump housing, the old pump fell out in pieces!   I’m now unsure of the correct orientation of the vanes, with respect to the shaft rotation, for the new pump installation.  I don’t see any directional arrows or other clues.  When I’ve got the housing open, which way should I orient the vanes for correct rotation?  The picture below is not necessarily right.

Thanks for all your help.  The collective experience of this forum is priceless.

[bobw]

Vanes should go opposite of what your picture shows, i.e. tips of vanes curling to the right when viewed from this side of the impeller housing.   Another way to do this is install the impeller key in the driveshaft, slide the impeller down the driveshaft making sure it engages with the drive key, then slide the impeller housing down over the driveshaft until it hits the top of the impeller.  Then, turn the driveshaft clockwise while pushing down on the impeller housing – the housing will slide down over the impeller with the vanes turned the right way.    A little grease, soap or vaseline applied to the inside of the impeller housing will make it slide down over the impeller real easy.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

2 users thanked author for this post.

aquasonic, Buster

[crosbyman]

if you plan to get infected and  start fixing oldies  you realy should download a copy of the Johnson service manual… 450+ pages of all you need to know

on J&E  oldies

 

https://watercraftmanuals.com/outboard/johnson/manuals/johnson-302231.htm

Joining AOMCI has priviledges 🙂

[Buster]

Thanks Bobw,

I like the second option.  I was thinking of making sure the shift is in forward, then turning the prop forward to rotate the shaft in the correct direction as the vanes seat in the housing, correctly.  I use a silicone plumber’s grease from ACE Hardware to lube the impeller and adjacent wear surfaces.

I’m sure it’s happened.  I was wondering what the motor would do if you fired it up with the water pump vanes angled the wrong way?  Think they would go to the proper trailing position on their own or just work less efficiently?   (or not pump at all?)

Buster

[aquasonic]

Once the motor gets going, the vanes will flip over to the correct orientation. This is, however, forcing the vanes to flip over in a confined area. For peace of mind, it’s better to reinstall the impeller to the proper orientation.

An older impeller that has “taken a set” from being in the impeller housing for some time is a different story. The flipping over of those vanes could result in damage to or destruction of the impeller. This is why you should not turn a motor counterclockwise unless you plan on relacing the impeller.

[Author]

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