Topic: 1958 Johnson 10 hp- worthy for resto? – Antique Outboard Motor Club,Inc

This topic has 9 replies, 8 voices, and was last updated 6 years ago by fleetwin.

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April 8, 2018 at 11:19 pm #9587
shoestringmariner
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EDIT: disregard my questions about compression . I forgot about a post where asked similar three years ago. My memory is fading + too many other interests

Hey everyone. Last year I picked up a 1958 10hp Johnson. I was running another one identical as a fishing motor until some issues early last year, so this one came up for sale complete with a pressure tank and new decals and I thought I’d pick it up as a spare/back up motor.

I dug it out of the shed and went through it a bit this afternoon. The compression isn’t great. About 72 PSI both cylinders. If I’m not mistaken, are these OMC motor is not a low compression motor to begin with? That’s what my current one is and it runs & idles OK but i’m not sure those numbers are good enough to put a fair bit of effort into this motor. It has new coils and ignition parts. The bottom end condition is unknown. (not sure how to check if the clutch dogs are good without opening it up, is there way?

As for the compression, I’ve read that running them can loosen them up and increase the compression a bit. What about head gasket thicknesses? Can I tweak that as a compression fix? Or will there be interference problems with the Pistons?
April 9, 2018 at 12:01 am #73640
need2fish
Participant
The ’58 range of Johnsons were amongst the most beautiful ever made.

Yes, OMC motors of that era typically have lower compression than mercs, but it’s not uncommon to have 100-120 in a motor that old.

I would check the gaskets, the reeds and the rings before calling 72 the real compression. If it’s been sitting for some time one or more of those might have issues.

I’d focus on the rings: Let it sit with some Kroil, Kerosene or fogging oil to see if that’ll loosen up rings.

No way to check possible upcoming clutch issues without opening the l/u. You can do it by only taking out the 6 screws holding the lower half of the gearcase on. Do not remove the gearshift pivot pin, just let the lower half drop by 1/2 inch, and you can see the clutch "teeth", with the aid of a dental mirror.
April 9, 2018 at 12:24 am #73641
frankr
Participant
US Member
I suggest you check it for battered-out wrist pins before putting money into it. Easy to do, remove plugs, stick a screwdriver into a plug hole, rotate flywheel while you follow the piston down with screwdriver (DONT push). Stop rotating flywheel when piston is about half way down. Now give a push on screwdriver. Any clunk you get is wrist pin wear. The more clunk, the more wear. Repeat with other piston.

I say all this because wrist pin wear is common on those motors. Actually, it is wear in the wrist pin bore in the pistons. Improved parts are available beginning with 1961 models. (Can retrofit)
April 9, 2018 at 1:20 am #73647
bobw
Participant
US Member
I have the same 1958 Johnson 10hp motor. Good advice from Frankr on the wrist pin issue – always a first good check. Assuming it passes that test, it could just be stuck rings or bad head gasket. Mine initially had about 80 psi in both cylinders. I soaked with some fogging oil and also found a bad head gasket. I now have about 95 psi and it runs great. Did all the other usual items – carb rebuild, new water pump, gear case reseal, all new gaskets. After I got it running I then did new paint and decals from NY Marine and it looks factory new again. The 1958 Johnsons had a great paint scheme and I would certainly say yours is worthy at least some effort to see if you can get it running.

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."
April 9, 2018 at 1:28 am #73648
bobw
Participant
US Member
Here’s after and before pics on my QD19.

Attachments:

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."
April 9, 2018 at 2:07 am #73650
shoestringmariner
Participant
Thanks guys.

@bobw, that is gorgeous.

@need2fish, I totally agree. The ‘58 is the best looking of the Johnsons. My next favourite is the 54’s

Silly thing here is I have four 10 horse Johnson’s and no boat to put them on. I sold my 12’ tinny for a 16’. I have a 14 foot plywood runabout. Maybe I’ll put one on there to play with and see if it will plane out.
April 9, 2018 at 10:39 am #73661
Steve D
Participant
(bobw your motor came out beautiful!) Shoestring – If everything checks out with the battered wrist pin bore syndrome, I wouldn’t worry too much about those compression numbers. I’ve had many 10s from the 50s that showed those numbers and ran great, started easy, idled down nice, and had good top speed. And as mentioned they may come up a bit too.

It’s also been mentioned before that numbers can vary between different compression gauges. I had Pugsley’s Marine, a local respected outboard repair shop, compression test 3 of my motors (a 10, an 18 and a 25) and all 3 showed exactly 13 lbs. higher than my gauge.

Here’s a ’58 powerhead that showed only 67 top and 70 bottom on my gauge but after doing carb, ignition, synchro, etc. it’s an excellent runner.
https://www.flickr.com/photos/55515333@ … res/JL77P9

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April 9, 2018 at 11:20 am #73662
crosbyman
Participant
Canada Member - 2 Years
I have never seen anything above 80 on the limited family of oldies I have worked on and they all ran fine for fishing duties. My mechanical skill level is limited to administering CPR and TLC (…no time to split any open or do a fine painting and decal job like a lot of you folks do.

Maybe not racing duties but for fishing and getting around they are fine motors enjoying a second life..and being enjoyed by their new owners
I have resold (snif snif) a CD , AD, 2 x 9.5 turtles and a 4hp just to recover my basic investment in 50$ motors and parts.

Maybe I have been lucky , maybe my meter is low ( I never tried a second one)

Joining AOMCI has priviledges 🙂
April 9, 2018 at 7:56 pm #73694
outbdnut2
Participant
US Member
I have six 10s from the 1950s, of which I’ve had time to get three of them running, and they all run good. I make a habit of not checking compression unless I can’t get a motor running good. My take on it is if a motor runs good, I don’t care what the compression is! One less thing to wonder about!…but that’s just my opinion on it.
Dave
April 11, 2018 at 2:55 am #73788
fleetwin
Participant
US Member - 2 Years
Boy, that is a beautiful paint job for sure….Like others have said, wrist pin/bushing wear is not uncommon with these engines, so I would stick with a 16:1 mix to provide maximum lubrication. The gearcase can be a weak point also, check and change gear lube often to avoid problems…Once the lower housing bushing is wallowed out, the gearcase is toast. These driveshafts are getting hard to find also…
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