Johnson HD-25 2-1/2 hp parts

[Buccaneer]

I have four HD-25 2.5 hp Johnsons.
I’m going to see which one is in the
best shape to keep for my collection,
then possibly sell the others in the future.
I believe two are 1947, one not sure,
and the other I have apart so far is a 1950.
Some general questions to tap your experience.

Will try to keep all the original parts to which
ever one I keep, but in case I need to
switch out parts,
Was there any noticeable changes throughout
the model years?

Does anyone have notes on the HD-25 regarding
what seals you used in the lower unit, or other
helpful tidbits?

The one I have apart has 75 psi on top and bottom
cylinders. Will check the others (except the froze one),
but is 75 psi considered so-so, good or great on
these models?

I believe a have a digital parts manual, and bookmarked
pages in the 3rd Edition Johnson manual.
Anyone have a digital owners manual?

I have several TD-20 5 hp Johnsons as well.
Which seems to sell better, the 2-1/2 hp or
the 5 hp? I know neither are worth a King’s Ransom!

Thanks for your input!

Prepare to be boarded!

[frankr]

I don’t think it applies to any of your motors, but there is some interesting reading in your service manual consisting of information about the Maverick Spark Suppressors and magneto magnet changes. But there always is the possibility that parts may have been swapped.

On a personal opinion note, I prefer the TD series over the HD. They just seem to be so much easier to make run right.

[aquasonic]

I can’t think of any mechanical changes at all through the production run. The only thing that comes to mind as far as change is the decals which changed in 1949. 1946-1948 decals are identical.

75 PSI is considered very good for an H model. I have one that tops 80 PSI, but 70-75 is much more common. These rotary valve motors are very unforgiving to low compression.

As far as which model, TD or HD is a better seller, I have no idea. It seems as though I see more TD models for sale, so it may just be availability.

[aquasonic]

I forgot to mention that the transom clamp screws also changed in 1949. They went from the brass pin style to the aluminum flipper style of the 1950’s classics.

The original seal numbers: 300599 lower seal, 300687 upper seal. The lower seal has been changed to 327031, and the upper is "not available" at ME.

[Buccaneer]

Thanks for the replies. It looks like the first HD-25 I pulled
off the rack was the best as far as compression.
Two others had even compression of 65 psi, and
the other, which probably has stuck rings, as I seen
signs of rust on the spark plug, had 54 & 59 psi.
I didn’t notice the difference in decals, but then again,
there’s not much for decals left on any of them.
Will have to look at the transom pads to see if my 50 model
is different from the others.
The prop shaft seal said "Garlock, Part # XX.
For fun, I’ll have to check the number and see if it jives
with any on this Garlock dimension chart…..
http://www.allsealsinc.com/klozure_catalog.pdf

I haven’t seen the drive shaft sealing system yet, but from
the diagram, it shows a spring and grease retainer below
a short tube. Is that a conventional seal, or more like
a packing that’s unavailable?

Hopefully I get at least one running good…… they’re
cute little power heads!

Prepare to be boarded!

[Buccaneer]

I thought I found one more HD-25 Johnson on the rack. Turns out
that it’s a HS-20. According to this chart,
http://www.maxrules.com/models/OMC_mode … 22-69.html
they’re both 2.5 hp, and the years produced over-lap.

HS-20 2.5 1941-49
HD-25 2.5 1946-50

Why would Johnson make two different 2.5 hp outboards?
It looks like the flywheels are different, but I’m not sure
what else.

Prepare to be boarded!

[aquasonic]

Here’s my understanding: The postwar HD-25 stands for ‘half size deluxe’ which means that it is 1/2 the size of the 5 HP T series, and the deluxe meaning auto-rewind. The HS-20 would be ‘half size standard’ which is mostly similar to the HD, but is the pre-war model and has a manual rewind pulley.

[bkrsdoz]

Not to highjack the thread but, what is the difference between the 1940 HD-10 and 1940 HD-15?
I have an HD-15, and haven’t seen many of them around.
It is the perfect match to my DT-10 condition wise.
Thanks!
bkrsdoz

[Buccaneer]

Aquaman, Thanks for the explanation,
would have never guessed!

Prepare to be boarded!

[aquasonic]

Anything for ‘Buck-an-ear’. (That’s a lot of money for corn). 😀

[Author]

Posts