1967 Merc 39 questions

[Rays39merc]

I dont know alot about outboards so have mercy. This motor has not been run in years but still turns over ok. Currently no spark etc. I plan on new points and such and probably a carb rebuild. But does anyone know what the compression should be. Also I am having a hard time finding out what type of two strke oil should be used and at what ratio to mix it at. Thanks for any help. the ser. # is 2130950

 

[Laddies]

Re: 1967 Merc 39 questions

About 100# compression, your on the right track for repairs after it runs you probably need to put a w/pump impeller in it. Any TCW-3 rate oil is fine at 50 to 1 mix.

 

[Rays39merc]

Re: 1967 Merc 39 questions

Ok thanks for the info. Yes if I can get it running then I will take a look at the water impellar as I am sure after 40 years its shot.

 

[Rays39merc]

Re: 1967 Merc 39 questions

I ran a compression test and ended up at around 90 pounds after several pulls. Or should it have jumped up to 90 after one revolution? Also the points looked ok, so I just touched them with an emery to clean them up, but have yet to see a spark. where else should I look.

 

[chrishayes]

Re: 1967 Merc 39 questions

As to your compression, I can give you input from what I did on mine. I have a different engine than you but the procedure should be the same. Remove all spark plugs after numbering them with a sharpie so you know where to return them to. spray some fogging oil into the cyl, let sit for a few minutes.Pull your rope and turn it over several times to get the rings and cyl loosened up a bit. reinstall plugs and wires. if the motor will fire, hook hose up to the water tube or use muffs(if impeller and pump are good) run motor for a few minutes but make sure that water is circulating. shut motr down. remove plugs again and ground them to the block, insert compression tester, pull rope as many times as it takes for the needle to no longer move. repeat as many cyls as you have and record numbers. reinstall plugs. You're done!