How to learn to repair and maintain vintage outboards?

[cocaptain5280]

I want to learn how to fix and rebuild vintage motors. I have two motors that both run, but they could definitely run better.

1. 1957 Evinrude Big Twin 35hp (with electric start)
2. 1961 Johnson Seahorse 10hp (pull start)

Thanks to LeeRoy’s Ramblings (online vintage motor knowledge base) and YouTube, I know how to replace a water pump and impeller, and I know sort of know how to change lower unit oil, but that’s really it. I also understand a lot of the part names from reviewing outboard diagrams.

My goal is to learn how to do repairs and maintenance on each of these motors and other vintage motors that I acquire in the future (I love classic boats). The problem is that I am overwhelmed by the amount of information online, and I want advice on how to learn these skills.

What is the best way to approach this endeavor? And where should I start?

For some reason I want to start with the 1961 10hp Johnson Seahorse because it is smaller and less intimidating than my 1957 35hp Evinrude Big Twin.

Thanks!

 

[Scott Danforth]

the best way to approach it is to have a sound fundamental mechanical aptitude and turn your own wrenches. for everything else there is the factory manual.

 

[cocaptain5280]

the best way to approach it is to have a sound fundamental mechanical aptitude and turn your own wrenches. for everything else there is the factory manual.

Right, but I only know what I know now. I am wanting to learn more through this process. I can turn the wrenches and work on both of these motors, it’s just knowing where to start.

Is there a general strategy to assessing a motor for maintenance and repairs? Or is there a set list of items I should work on first? The motors run now, but I want to “go through and clean everything out while replacing what’s needed”, so that they run better.

 

[Scott Danforth]

Start with the basics....start with reading the manual for the motor your working on.

Generally to assess a non-running motor.... Start with the fundamentals of the internal combustion motor....suck, squish, bang, blow

Look for compression, spark and fuel

 

[ahicks]

Agree with Scott. Most people learn best by doing. If you get into any part of it and don't understand, that's where the learning starts. Let youtube and google be your friends.

Successful techs, in addition to being mechanically inclined, are also strong when it comes to logic. Successful trouble shooting requires they use a lot of it. Without solid troubleshooting, many, many, parts are replaced with absolutely no good reason, just to see if they fix an issue. Kind of like throwing stuff at a wall. If you throw enough, sooner or later something is going to stick....

Regarding the 2 engines you have, figure out how to evaluate them. If they run OK, there's a pretty good chance there's not a lot you can do to make them run "better".

 

[roffey]

just some advice from the peanut gallery, make sure you look at several videos and don't take the first one. Some of these jokers will show you how to really break your motor, lol. If it does not make sense then look at a different video and read the comments as someone will normally chirp in a call them out.

As an example ... look for "f150 ecoboost air intake delete" There is a air flow shaper that will increase the air flow to the turbo, these guys are telling you to take it out?

 

[cocaptain5280]

Agree with Scott. Most people learn best by doing. If you get into any part of it and don't understand, that's where the learning starts. Let youtube and google be your friends.

Successful techs, in addition to being mechanically inclined, are also strong when it comes to logic. Successful trouble shooting requires they use a lot of it. Without solid troubleshooting, many, many, parts are replaced with absolutely no good reason, just to see if they fix an issue. Kind of like throwing stuff at a wall. If you throw enough, sooner or later something is going to stick....

Regarding the 2 engines you have, figure out how to evaluate them. If they run OK, there's a pretty good chance there's not a lot you can do to make them run "better".

Thanks for this.

 

[briangcc]

Look into local technical classes. Around me, BOCES has adult ed small motor repair which includes outboard motors. You might find something similar. How far back (ie. old motors) I couldn't tell you as I haven't looked that deeply into it....YET.

 

[Downwindtracker2]

Manuals vary . I try always to get the factory service manual. On outboards I have '60s to early '70s era Mercury and a '95 Yamaha, found online.. The Mercury is good, fairly complete with a little bit of teaching, whereas the Yammy is just a list of steps in correct order. I guess they assume you know what you are doing. It's also good to supplement the factory service manuals with some thing like Clymer(Seloc), they will add some teaching at the expensive of thoroughness. They only have so much paper.

Outboards can fun to work on, the Mercs are like Swiss watches. Now if I can get that 9.8 that I made from a 7.5 and 9.8 to fire.............

 

[tomhath]

Don't overthink it. A motor needs three things to run: Compression, Spark at the right time, and proper Fuel/Air mix. Verify each separately.

If you have good compression, move on. Otherwise learn the causes of low compression on that engine.

If you have a strong spark, move on. Otherwise learn what causes weak or missing spark.

If you get this far and the motor doesn't run well, learn how to adjust and rebuild a carburetor.

 

[Silvertip]

It appears to me you have some very basic mechanical skills but you lack an in-depth knowledge of how two stroke and four stroke motors operate. Then there is the electrical part of the equation as well. To be "skilled" at repairing any type of equipment you need understanding of the various bits. You cannot possibly diagnose issues unless you understand how things work. So my suggestion is study gasoline engine principles. Then basic electrical theory and diagnosis. Any by the way, electrical work requires use of specialty equipment, the most basic of which is the VOM. Knowing how to use it and to understand what it is telling you is essential for diagnostic work. Just replacing parts until you get lucky and engine runs does not make you a "skilled" mechanic. There is no shortcut to this field of endeavor.

 

[82rude]

As briangcc mentioned ,you cannot go wrong taking a course in small engine repair.Many collages have night courses in that field and many others.Our school had a basic course and an advanced one for a reasonable price .Both classes had people of all ages in them.

 

[3rdtimesthecharm]

Join the Antique Outboard Motor Club. aomci.org

 

[racerone]

Old motors need a complete evaluation before spending money on them.----You should not spend money on new points / coils / condensers if the lower unit is scrap !!

 

[Ned L]

I would second the AOMCI.

The two outboards you have are quite basic and simple to work on and get to know.

 

[DeepCMark58A]

First thing I do on a vintage motor is a compression test, this is vital to learn if the motor is restorable. Basic things I do to a new to me vintage motor 1 replace the fuel lines 2 rebuild the fuel pump with genuine brand parts 3 clean the carbs inside and out. Those are the main culprits of a motor that runs but could run better.