Topic: 1960 Johnson 3 HP JW-16 compression issue – Antique Outboard Motor Club,Inc

This topic has 9 replies, 6 voices, and was last updated 4 years, 4 months ago by crosbyman.

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June 29, 2021 at 1:35 pm #241555
mikekolbus
Participant
Folks
I am seeing low compression issues 14.1 lower cylinder, 14.7 upper cylinder, I have replaced the rings and honed the cylinders. any suggestions ?
Mike K
June 29, 2021 at 2:03 pm #241557
Buccaneer
Participant
US Member
Is that a “psi” reading, or metric of some kind? If psi, I’d think you’d
get even a higher reading with no rings on the pistons.
If it’s a psi reading, time for a new compression gauge.

Do you have any “rebound” when you spin the flywheel by hand?
Were the cylinders “lightly” honed?

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June 29, 2021 at 4:02 pm #241563
Mumbles
Participant
No, its time for a new head gasket.
June 29, 2021 at 7:25 pm #241586
crosbyman
Participant
Canada Member
and how did we arrive there…. what is the issue with the motor that started this search for compression #s ???

they seem close so the head gasket middle section must be blow as per Mumbles suggestion 🙂

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June 29, 2021 at 7:57 pm #241587
Buccaneer
Participant
US Member
I would have expected that a gasket malfunction of that magnitude
would have been noticed when the head was off for the ring job,
but perhaps not.

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June 30, 2021 at 1:17 am #241601
JOHN HOLBIK
Participant
Must be a pretty accurate compression tester if your able to measure in tenths of a pound increments.
June 30, 2021 at 7:01 am #241602
stanley
Participant
US Member
Coincidently,14.7 psi is atmospheric pressure at sea level.
June 30, 2021 at 11:28 am #241614
Mumbles
Participant
My digital compression gauge reads out in tenths of a pound, but only five at a time!
June 30, 2021 at 12:37 pm #241621
Buccaneer
Participant
US Member
I’m starting to wonder if Mikey is “spoofing” us, lol.

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June 30, 2021 at 6:08 pm #241648
crosbyman
Participant
Canada Member
suggestion….. find another JW …they for for 50-60$ cdn around here

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