58 johnson 35hp compresion question

T

troyl_1969

Recruit
Joined
May 18, 2008
Messages
3
I think its' to low on compresion. Getting fuel and good spark only starts when it wants to but dies quickly. Did compression test. one was at around 60psi and the other was about 65psi. Shouldn't this be between 90-100.

Thanks
 
J

Johnson110

Chief Petty Officer
Joined
Dec 31, 2003
Messages
640
Re: 58 johnson 35hp compresion question

Try seafoam decarb, then see what your compression reading is !
 
samo_ott

samo_ott

Vice Admiral
Joined
Jun 18, 2006
Messages
5,125
Re: 58 johnson 35hp compresion question

Yes, that is low. It might run, and if it does it will probably be low on power.
 
jbjennings

jbjennings

Captain
Joined
Jul 18, 2007
Messages
3,903
Re: 58 johnson 35hp compresion question

Be sure to use another gauge before you get too worried. Lots of people have used gauges that were faulty and gotten all upset for nothing. It very well could be bad and if they actually are 60 or 65lbs. it's a junk powerhead. But, usually when they go bad one is bad and the other is o.k., unless it's just completely worn out. I'd pull the bypass covers and possibly exhaust covers and see what the rings and pistons look like. If you see any grooves or scratches you'll know for sure your powerhead is ruined.
JMO,
JBJ
 
tashasdaddy

tashasdaddy

Honorary Moderator Emeritus
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Nov 11, 2005
Messages
51,019
Re: 58 johnson 35hp compresion question

are you rope pulling to get compression, or using electric start, rope pulling activates the compression release valves, so you would get a low reading. you have disable pressure relief, to get accurate readings.
 
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