Sea king 12 help

[frankr]

OK, now make sure you have good compression on the top one. Don’t ignore the simple stuff either–could just be a bad spark plug. If still no luck, time to pull the flywheel. Lots of those old OMC motors have bad (cracked) coils and produce a spark, but won’t run. You wouldn’t be the first one to be fooled. Actually, I guess that one has an inspection plate in the flywheel, so you don’t have to pull it except for if it needs service.

[wildwestclassics]

So..I regapped the plugs and crimped the spark plug boot a bit and now it runs on 2 cylinders. Lots of power. No clue what happened

[garry-in-michigan]

A bad head gasket will usually show up in a compression test. A shorted spark plug will show up by switching the plugs. If the non running cylinder follows the plug, try a new plug. If it doesn’t, look for a bent or broken reed valve, or bad manifold gasket. Sometimes a crack in the ignition wires insolation will show up when the wire is plugged into the spark plug, but pulled away from the spot where in was shorting when moved to the spark tester. Make sure the insulting sleave on the magneto stop switch wire is in place as these can short to the motor cover in certain throttle positions causing intermittent problems. . . . . ❓

[garry-in-michigan]

It could have been a bit of carbon shorting out the plug that you dislodged when you gapped the plug. Glad to see you got it running.

[wildwestclassics]

Thanks for the help. I’m going to Lake test it and see how it does

[1946zephyr]

If that’s the older wedge block 12, there won’t be any worry about head gaskets. It has a non detachable head. The next gen 12 will though. Its similar to the old QD and Fastwin.

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