Restoring a Johnson CD-12, 1955 5-1/2

[HighTrim]

Re: Restoring a Johnson CD-12, 1955 5-1/2

Hard to tell from the pics, but doesnt look bad from what I can see. If the rings bounce, install the new head gasket and see what you have.

Those coils are very new. Looks like one of the leads was routed too loose and got caught though. If continuity is still good, repair that wire and leave them. Pull that wire tight against the coil before tightening down the screw.

 

[Bwana Don]

Re: Restoring a Johnson CD-12, 1955 5-1/2

Didn't even notice the wire chafed.

"If the rings bounce," you're going to have to explain that a little more.

The pitted area is about the 1/2 size of a dime. It's too small and shallow to even photograph. Barely noticeable by eye but my machinist finger picks it up.

Thanks guys.

 

[HighTrim]

Re: Restoring a Johnson CD-12, 1955 5-1/2

Sorry I was thinking you had a QD, where the bypass covers are removable so you can test if the rings are stuck at all. You could remove the exhaust cover to test them. Warning though, sometimes that can cause more issues with broken bolts and such. It happens.

Once exposed, you should be able to bounce the rings in their groove with a small screwdriver. If they dont bounce, they are stuck, and compression will suffer. If it is just carbon, Sea Foam or Engine Tuner will usually cure it. If they are rusted stuck, you usually need to pull the pistons.

 

[Bwana Don]

Re: Restoring a Johnson CD-12, 1955 5-1/2

I ordered the full gasket set from Vintage Outboard. Around $28.00 plus shipping. I'll tear the power head apart and hone the bores and put the new rings I have in it. I've got a bore gauge so I'll measure the bores for wear. They are 1-15/16 or 1.9375 stock size. Overkill, maybe but this motor will be used a lot.

I'll keep you guys updated. Thanks for the input.

Hey Hightrim I've got a QD-16 to rebuild so I'll remember that trick. Thanks.

 

[Bwana Don]

Re: Restoring a Johnson CD-12, 1955 5-1/2

I'm getting a flex hone for deglazing the cylinders. What grit should I use? I'm thinking Silicon Carbide and 180 grit. Thoughts?


I know it's probably more than I need but, I wanted to take an outboard apart. I never had one apart before. Once it's apart might as well ring it and hone it.

When I was working my way through college I was an inspector/machinist. We made hubs for big diesel trucks and connecting rods for the big diesel engines that went into the M1 Abrams. I used to check pallets of parts with a bore gage, until my arm hurt. Well tomorrow I'll check the cylinder bores with yup, a bore gage.

Thanks
Don

ps my gasket set shipped.:happy: Hey it's the little things in life.

 

[HighTrim]

Re: Restoring a Johnson CD-12, 1955 5-1/2

The flex hones are nice, and expensive! lol

There issues are that they can only be used on one sized cylinder, and they tend to blend any issues to where you cannot see them. If you get a solid stone glaze breaker, you can more easily see any issues, and you will save yourself some cash. They are much cheaper, and can be used on a wider diameter of cylinders.

Just a thought.

 

[Doorknocker1]

Re: Restoring a Johnson CD-12, 1955 5-1/2

What is the compression? I personally would not bother rebuilding it unless it truly needs it.
They are fairly simple motors, so the tune up should be no problem. Any problems let us know, and keep us updated!

How does the water pickup tube connect to the water pump & powerhead on a 55 CD-12

 

[racerone]

It fits in a grommet half way up the exhaust housing and into a grommet in the pump.----Put the tube into the exhaust housing FIRST.

 

[Doorknocker1]

It fits in a grommet half way up the exhaust housing and into a grommet in the pump.----Put the tube into the exhaust housing FIRST.

Thank you.. I need to take it back apart again..

 

[racerone]

Was the tube in the pump when you assemble and tried a " stab in the dark " to assemble this ?

 

[jbcurt00]

How does the water pickup tube connect to the water pump & powerhead on a 55 CD-12

Please don't hijack another members topic.

Start 1 about your 55 CD-12 and ask rebuild questions about your motor there

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