Re: Johnson 3HP JW-17 Compression woes

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fleetwin

US Member - 2 Years
Replies: 4737
Topics: 46
#79802

OK, well don’t let that cleaner soak too long, overnight is fine though. Be sure to fill the cylinders with oil afterwards or get the engine started to get rid of the cleaner…
Yes, probably a good idea to use the OMC gasket sealer on the new head gasket, but this is only helpful for external water leaks. Gasket sealer will not help with leaks into/out of the combustion chambers. If you decide to pull the head again, you should replace the head gasket again, don’t reuse it, I would probably rough up the cylinder walls with some fine emery as well. The head bolts are torqued to just 80 inch pounds, in stages, starting with the center bolts.
I would probably use the OMC typeM-847 sealer on that exhaust cover gasket, those bolts love to loosen up causing leaks.
The high speed needle (bottom one) is backed out 3/4 turn after being gently seated.
The low speed needle (top one) is backed out 1.5 turns after being gently seated.
These settings will get the engine running, don’t forget to make sure the packing nuts are tight enough so the needles don’t move on their own…
You will be able to make some adjustments in the barrel/tank, but it can only be "dialed in" while running on the boat. Dial in the high speed needle first, then the low speed needle…