Re: problems with the 1957 35 hp johnson

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jerry-ahrens

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Replies: 986
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#72834

Because of the age of these motors, My opinion is to not even try to start them until they have been gone through. Personally, I’ve always done it that way.
1. Check compression first, if it’s not good, then your done, unless you want to rebuild it.
2. Pull flywheel, replace points, condensers and coils if needed. Check the mag plate bushing for wear or slop.. if it’s worn out, your motor will not idle very well, or not at all. Go with OEM parts here for sure, aftermarket is junk IMO.
3. Clean and rebuild carburetor, I only use an OEM kit, that comes with a new float. Clean out the old needle packing washers and replace with new. The only good packing washers I’ve found are OMC/BRP. Aftermarket ones will squash out and not seal properly. Just my humble opinion..
4. New spark plugs if needed (Probably does)
5. Pull lower unit, replace water pump and housing, if worn. Don’t forget the wear plate under the impeller. Replace if worn or grooved out.
6. On OMC engines of the 50’s era, I replace the shift rod O-ring weather it leaks or not, along with any other seals that look bad. I check out the clutch dog and gears while I’m in there. Reassemble and pressure test for leaks, fill with new gear lube.
7. Replace the fuel/air lines on powerhead.
8. If it has a 2 line pressure tank, that needs to be gone through as well, with a new pump diaphragm, and top cover gasket. Replace the 2 line hose if it needs it.
9. Don’t forget the 2 line connector that plugs into the motor. The O-rings should be replaced.
Of course there are other things that may need attention, but the above is a good way to get the basic systems back in order. Opinions will vary, but I want my engines to run good, and I hate problems on the water! Hope this may help to get you going.