1941 Johnson HD-10 Water Pump/impeller

michiganspeed · Oct 8, 2008

I acquired a beautiful 1941 Johnson HD-10 2.5hp from an elderly woman whose husband used the motor regularly use until about 9 years ago when he passed away. My question is does this motor have an impeller/water pump? There is a series of holes in the shaft and a hole at the base of the shaft near the cavitation plate. I ask because I put a little fuel mix in the tank after being stored for almost 10 years and it fired on the 4th pull. The 5th pull fired and the motor came to life and aside from a couple hic-ups at first it idles great & accelerates well also. Once it was started and running smooth I looked to see if water was coming out of the holes in the shaft and there was only a faint trickle of water. I did not want to overheat the motor if it was not getting proper water circulation so I shut it off. If this does need an impeller any idea where to find one and how to go about installing it? The motor is absolutely fabulous so I would love to put this on the little aluminum boat I use for small inland lakes and take off my Minn Kota.

tmcalavy · Oct 9, 2008

Re: 1941 Johnson HD-10 Water Pump/impeller

That one may be old enough that it has a recirculating water circuit rather than a pump/impeller. Forward motion of the boat pushes water into the circuit and nature takes over from there. After start-up, you throttle up pretty quickly to feed the circuit. May be wrong though. Someone else will probably know/confirm for sure.

michiganspeed · Oct 9, 2008

Re: 1941 Johnson HD-10 Water Pump/impeller

If it makes any difference I was running the motor in a barrel and not on my boat in the lake. Not sure if this matters in regards to the recirculating water circuit that was mentioned.

mchin · Oct 9, 2008

Re: 1941 Johnson HD-10 Water Pump/impeller

I believe those motors have a wiggle pump that fits just under the lower unit cover plate. Ya take off the prop and unscrew 2-3 screws, lift the cover and inside you'll see a round rubber ring with a small tab sticking out. I believe someone is still making these, I am pretty sure I have seen ads online and in the back of the antique outboard magazine. Also, are you sure it's a hd 10? I knew of a hd25 and hd5, but not a 10. if you go to amoci.org, you can post a free ad asking for that part, I am sure someone will tell you where to get them. My experiences with the wiggle pumps, on both johnsons and older gales is that they work well, but do not pump like an impeller does, they last a long time, but are not very tolerable of sand and sediment.

Joe Reeves · Oct 9, 2008

Re: 1941 Johnson HD-10 Water Pump/impeller

I don't have the book on the HD10 but the HD25 & HD26 have a centrifugal type pump impeller in back of the propeller as MCHIN states. The part number of this impeller is 300583 and I have no reason to believe that the HD10 model would be any different. Some dealership or other outboard repair shop may still have one on their shelf, check around.

CATransplant · Oct 9, 2008

Re: 1941 Johnson HD-10 Water Pump/impeller

Check here:

http://home.earthlink.net/~flyingscott/

Send the guy an email and see if he has the part for you.

F_R · Oct 9, 2008

Re: 1941 Johnson HD-10 Water Pump/impeller

Nay. Lets start off with the HD-10. It is a 1940 model. It is different than the Post-War HD models such as HD-25 etc. You can see it at http://www.old-omc.de/j_1940/seite_09_16.jpg
It does not have the wobbler pump like the HD-25, nor a more modern centrifugal impeller. The brochure says it has a plunger pump.

Now, I will have to admit that it is too old for my expertise and I don't know the details of the pump. Only what I read in the brochure and see in the picture.

wbeaton · Oct 9, 2008

Re: 1941 Johnson HD-10 Water Pump/impeller

I have a couple LT-38's which are basically the same, but 5 hp (well 4.2 hp to be exact). I have not started working on them yet so I'm not much use to you either. However, I can tell you that the water pump is like a piston that sits in a housing behind the prop. It needs to be run on a boat. It does not work very well in a tank. The folks over at AOMCI.org will have more information.

michiganspeed · Oct 10, 2008

Re: 1941 Johnson HD-10 Water Pump/impeller

I really appreciate all the input. I was off by one year as the HD-10 was indeed a 1940 model - thank you for that correction as verified here http://www.marineengine.com/manuals/johnson/

TN-25 · Oct 10, 2008

Re: 1941 Johnson HD-10 Water Pump/impeller

The 1940 motors are shown here.

For 1941 many Johnson turned into "streamliners". As for the 1.5 single, 2.5 & 5 horse twins, they were basically little more than restyled streamlined 1940 motors except as F R noted. Then production was interrupted for WWII.

After the war the exposed starter pulley versions of the 2.5 & 5 were
dropped, as were both versions of the 1.5 horse single. The early-1930's
-looking 9.8 horse KS was dropped while the same motor with a ready-pull
starter carried on through 1948 as the KD (ultimately replaced by the
revolutionary QD-10 10-horse for 1949). Post-war Johnsons switched from
being painted "dull aluminum" to "sea green". The post-war Johnson lineup is shown here.

The 2.5 looked and was engineered like the 5-horse. Those motors, as was
already said by several previous posters, had a water pump on the prop
shaft. It was located behind the access plate which was behind the prop.
(See below for the attached photo of the TS motor.)

The first true streamliner was the 1940 SD-10, a 16-horse alternate-
firing twin whose block was the 22.09 c.i. granddaddy of the 18-20-25
motors except that it was a rotary valve instead of reed valve. The old
SD also had a pressure-vacuum cooling system with no water pump at all
(prop forced water up the pickup tube at the base of the exhaust and
drew it back out by vacuum in the slipstream of the slotted prop-mounted
water outlet. It worked because this 16-horse motor had no reverse or
neutral. No outboard motors had a neutral or reverse gear prior to the
1949 QD-10).

Some of these pictures are from my old Johnson manuals, while the links were provided by http://www.old-omc.de/

michiganspeed · Oct 10, 2008

Re: 1941 Johnson HD-10 Water Pump/impeller

Appreciate the illustration of the 1940's line-up - some great info on there.

mchin · Oct 13, 2008

Re: 1941 Johnson HD-10 Water Pump/impeller

this site maybe able to help - he's a seller of impellers of all sorts.
http://www.dewdropimages.com/impellers/index.html

1941 Johnson HD-10 Water Pump/impeller

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