Johnson MS38/MS39 Advice Request

[Mike Barthel]

Hello,

I’ve been a member for a few years and I’m just starting to restore some old outboards now that I’ve retired.  Currently, focused on three Johnson 1.1 oldies.  One MS38 I’ve had for 50 years but haven’t run it in about 40.  Another MS38 I purchased on FB Marketplace…is missing some parts.  I also picked up a pristine MS39 at last year’s Tomahawk WI meet.  I’d like to get them all running if I can find some replacement parts.

Since they are so old, parts are hard to come by.  So now my question.

Are there any substitute magneto parts that will work for these motors?  Meaning including coils, condensers, spark plug wires?

Any additional advice is also welcomed.

Thanks!

[JOSEPH BRINCAT]

Mike,  before you get too concerned about magneto parts, consider that often the ignition coils on these old motors are good. First thing that I would do is clean the points on each motor and pull them over to see if they have spark… you might be pleasantly surprised. If no spark, do you have a way to test the coil? There is a simple test that can be done with just a VOM meter… not absolutely definitive but a first indication of condition. Also, old condensers are always highly suspect… and easy to change with generic condensers of .22 mf size. condensers.

But first clean the points and try… Let us know what you find

Joe B

[Buccaneer]

Here’s a photo of my MD-38 magneto.
Are your coils the same?
Possibly the Johnson DT-38 would use the same coils as well.
First though, do what Joe suggest.

Prepare to be boarded!

[Tubs]

Your magneto is used on many small horse power , pre WW-II, Johnson, Evinrude, and Sea King outboard motors. It often wont produce a spark when they sit for a long time. As stated above, the first thing is to cleaning the points. If just cleaning the contacts doesn’t bring back the spark you need to un-solder the wires, and take the points apart. Clean all the metal parts. Notice where the insulators go. The insulated pin that works the point has a flat side and a round side. The flat side goes to the cam. I have had a lot of motors with this magneto and many of them wouldn’t spark when I got them. It was never a bad coil. This is the replacement condenser I use.

A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.

[Mike Barthel]

Thanks to you all for the sound advice and the helpful photos.  It is just what I was hoping to hear!  I’m traveling for a week, but can’t wait to get back and clean and test these magnetos.

[Mike Barthel]

I’m back working on this magneto cleanup.  Buccaneer, I found this MD-38 post from you in 2020 (johnson-md-38-magneto).  Would it make sense to use this as a basis for MS-38 work?  It looks like great background info.

[Buccaneer]

Mike Barthel wrote:

I’m back working on this magneto cleanup.  Buccaneer, I found this MD-38 post from you in 2020 (johnson-md-38-magneto).  Would it make sense to use this as a basis for MS-38 work?  It looks like great background info.

If anything in that thread helps, use it.
Hopefully you don’t have to do that same coil swap
as I did, as they’re no fun!

 

Prepare to be boarded!

1 user thanked author for this post.

Mike Barthel

[Mike Barthel]

Quick project update:

The magneto has been rebuilt and tested with a multimeter.  The coil tested fine, but I replaced the condenser per Tubs’ recommendation.  A big thanks to Tubs, Buccaneer, and Joe B. for your sage advice!

I also had some gas tank repair work done at a brass instrument repair shop.

Next step is to clean/reinstall the carb, reinstall the gas tank and magneto, and test for compression and spark.  I will report back.

If I do a full restore it will likely be painted the original gray.

Thanks!

[Buccaneer]

Hopefully you have nice hot spark now, and may your
gas tank play some sweet music!

Prepare to be boarded!

2 users thanked author for this post.

Tubs, Mike Barthel

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