15hp Johnson compression low?

duckiller

Recruit
Joined
Jul 31, 2005
Messages
1
Hi all,<br /><br />I have a 1993 15hp Johnson that has an even 90psi in each hole. <br /><br />Does this sound acceptable? <br /><br />Thanks in advance for any info.
 

Walker

Captain
Joined
Jun 15, 2002
Messages
3,085
Re: 15hp Johnson compression low?

Its been my experience that especially on these smaller motors, if they will start with either pull rope or electric starter, then they have enough compression.
 

DHPMARINE

Captain
Joined
Dec 16, 2003
Messages
3,688
Re: 15hp Johnson compression low?

90 PSI is a little low for a 1993 15 HP,but generally we use 70 PSI as a cut off.Below that,all the work you do is a gamble as to whether it will run or not.<br /><br />DHP
 

jameswilson95

Seaman Apprentice
Joined
Jul 27, 2005
Messages
43
Re: 15hp Johnson compression low?

throw some oil in each cylinder - just enough to wet the rings - and do another compression test. If the pressure goes up then your rings are probably wearing a bit (this would be normal for an older engine or one that has alot of hours.<br />Just a thought...
 
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