Johnson HD-25 "outboard or anchor?"

[oltimer]

Looks like your getting there. On the wires going to those points; make sure you use Electrical cleaner on them. What I do, is back the screw off so they are just hanging open/loose and spray the old oil out of them. You want good contact on these connections. On the cooling jacket/carb area, I have taken that system right off and made a new gasket to stop water leakage into the engine when I thought I had everything up to snuff. Found this out after many hours and some tips from my oldtime dealer that serviced these year in and out.

[Anonymous]

Before you tear into those motors to replace the rings, run a healthy dose
of something like Sea Foam through the gas.
It will clean the old carbon from the rings and the compression might come up.
Google De Carbing outboard motor.
Back in the days your motors were running oil was dirtier than now.
I have a Johnson CD12 that had comp. numbers in the low 60’s when I unstuck it.
I ran a rich dose of Sea Foam through it and have run S/F in the gas since and
now the comp. is in the mid 80’s.
Good luck with your motors.

Steve A W

[brian]

Running in a tank is not a sure test of how they will run on a boat. If you get out on the water just be sure you go no further than what you are willing to row back in. I often take a backup known good motor like a Lightwin when testing on the boat.

[oltimer]

quote Steve A W:

Before you tear into those motors to replace the rings, run a healthy dose
of something like Sea Foam through the gas.
It will clean the old carbon from the rings and the compression might come up.
Google De Carbing outboard motor.
Back in the days your motors were running oil was dirtier than now.
I have a Johnson CD12 that had comp. numbers in the low 60’s when I unstuck it.
I ran a rich dose of Sea Foam through it and have run S/F in the gas since and
now the comp. is in the mid 80’s.
Good luck with your motors.

Steve A W

I have been running that stuff since the 1970’s when I purchased it in Duluth. There was none of it in Canada at that time. Your motors will drip all the time at the bottom; but you will never ever get carbon build up. I normally "assume" all guys working on these engines at least pull the heads and LOOK? I run a 1/2 ounce per gal of gas

[Buccaneer]

I inspected all the rings via the ports when the carbs were
removed. Poked all the rings with a plastic rod to
ensure they weren’t stuck. Did find a lot of gooey
carbon in the bottom of the power head and the
exhaust leg.
I pulled the front cover off the power head of the HS-20
(that’s stuck) this morning. More rust than I wanted to
see in the crankcase. Threw in in my bucket of acetone / ATF
for now. I have a parts HD that I may try to scavenge
parts to make one more running unit.
Anyone ever try, or go to the trouble of planning down the
crankcase halves and then line reaming the crank journals
to tighten up the crankshaft fit? Not sure if it would work
out, but just a thought!

Prepare to be boarded!

[oltimer]

Not what your suggesting, and it might end up being a no no, with the knowledge I got in the machine shop. What I did in the bottom end of the crankcase was bor out a slot, and put a o-ring in to seal it up better for the crankshaft leaks. Works very good.

[Buccaneer]

Oltimer, could’t you bore out the top and bottom
of the crank case for a regular seal?
I have no milling machine, so probably beyond my
capability.
My "Parts" HD-25, which was loose, but had low
compression, had stuck rings. The crank in it looks
good, so I may throw something together using the
HS-20 and the "parts HD-25".

Prepare to be boarded!

[oltimer]

It’s touch and go as far as material/metal available on the bottom end. Total material available: 1.146. Crankshaft at that fit: .685. When you subtract that portion from 1.146, sure does not make it easy to find that thin of a fit seal; but it "might be available"? Remember the seal has to have metal holding it to when doing the calculations? The oldtime friend of mine that owned a dealership and large shop is the one who recommended to o-ring the bottom; that’s why I took the easy way in doing it. He was telling me they did several like that, and it works very soundly.

[Buccaneer]

Oltimer, are you talking about an O-ring installed in a groove
machined in the crankcase bottom journal, or in the
cap that bolts on the bottom of the crank case?
P.S.- those 1-3/8" diameter pistons sure are cute!
Thanks.

P.S.- I measured the crankshaft "mains" at .680
on my veneer caliper, but maybe I need to go
digital……… those little lines are getting hard
to read!

P.S.S. – I had a link to SKF where you could search for a
seal by part number or "inputted" desired size.
It’s not working anymore.
Anyone know of a similar web site?

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Prepare to be boarded!

[oltimer]

In the bottom journal Buccaneer.

[Author]

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