Johnson 115 Compression Question?

J

James Island

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May 17, 2010
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I took my 1996 Johnson in for yearly tune up and the guy there says the compression was 110-110-110-60. He then checked the cylinder and said it looked "great" and that the rings surely would have damaged the cylinder if it were damaged. He said in his 25 years he hasn't seen this and was trying to avoid the expense (my expense) of pulling the piston to check the rings when the cylinder looked fine.

Anybody have any idea what might be causing this. This motor ran GREAT last year before storage.
 
tashasdaddy

tashasdaddy

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Nov 11, 2005
Messages
51,019
Re: Johnson 115 Compression Question?

try a decarb. could free up the rings. i would redo the compression test. Is he a JOHNSON Mech, or just works on different outboards?
 
J

James Island

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May 17, 2010
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Re: Johnson 115 Compression Question?

He did do the Johnson tune up decarb and let it soak a couple days. The Marine sells mainly Yamaha but they are a large marina that works on all types. He said the cylinder is clean as a whistle. He said he was going to get his three guys all together to "put their heads together" on it. If the ring was bad...wouldn't the cylinder show signs. And Why did it run soooooo well last season and now this.
 
N

noelm

Senior Chief Petty Officer
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Mar 8, 2005
Messages
761
Re: Johnson 115 Compression Question?

rings do not need to be "bad" to lower compression, they can stick in the piston and not create the seal needed for compression, have they removed the head to at least inspect the bore and piston?
 
J

James Island

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May 17, 2010
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Re: Johnson 115 Compression Question?

Yes they did remove the head and replaced some gaskets as well. Is the only logical next step to remove and check the piston?
 
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