How do I remove dried gas varnish from Martin 20 motor

[chevy55belair]

I am new to the Antique Boat Motor Scene. This weekend I purchased a Martin 20 boat motor. I was able to fire it up with starting fluid and ran it for about 4 seconds and shut it off.
I looked in the fuel tank and there is flaky dried varnish in the tank.
Any suggestions as to how to remove the varnish ????
Once I have the varnish cleaned out…is there any precautionary steps I should take before starting it on the mixed fuel ???

Any input members can provide on this newly discovered Martin 20…please share it with me and other members.

Regards Steve Bowling Green Ohio

[crosbyman]

some folks use lacquer tinner and a handful of nuts or small gravel and shake it out rinse and do over again and rinse.

check any filter shutoff valve vents for crud overall the carb change gear oil, impeller etc…. usual stuff and don’t use to much if any starter fluid it washes out the coating of oil on the innards 🙁

Joining AOMCI has priviledges 🙂

[Bob Wight]

I recently cleaned a heavily varnished tank using denatured alcohol. I let it soak for a few hours, then threw in a bunch of hex nuts and shook it up real good, drained and rinsed a 2nd time with the alcohol – cleaned it up real good.

https://www.walmart.com/ip/Klean-Strip-Denatured-Alcohol-1-Quart/23232923?athbdg=L1200

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1955 Johnson QD-16
1957 Evinrude Fastwin 18
1957 Evinrude 3022
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."

[frankr]

I use plain ol’ isopropyl rubbing alcohol from the drug store or grocery store, with a couple of handsfull of old nuts and shake till your arms fall off. it’s cheap and not as flammable as lacquer thinner or gasoline.

However, you might consider backing off and form a plan of action for your Martin. Those Martin two-piece tanks are almost guaranteed to leak badly. Martin assembled them with gobs of some kind of sealant which squeezed out inside the tank and comes loose, making traditional cleaning difficult. I suggest you do the other restoration work first, leaving the tank for the last project after you are satisfied you are going to wind up with a good running motor. (And they are good running motors).

When you are ready to tackle it, take the tank apart and clean all that crud out. There are gasket kits available for it. OR, on mine I used an aircraft tank sealant, which I was real satisfied with. I’ll dig up the details of it, if you are interested.

[jcrigan]

I use ammonia in cleaning out tanks. Like Frank said, the tank uses gaskets and they do dry out and leak. You can get parts from Larson’s outboard service. Make sure there is grease in the gearbox. I use John Deere corn head grease in mine. Fuel oil ratio is 3/4 pint oil to a gallon of gas. I use a 16/1 ratio. Nice little motors, hope it runs well for you.

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