compression #'s for a 1987 johnson 150

bajabassboat

Cadet
Joined
Apr 3, 2007
Messages
18
I looked at a 1987 Johnson 150 and all the cylinders read 81-85. The motor was not started for 6 months so are these bad #'s ? Would running the motor cause the compression #'s to get highter? Is this 87 johnson 150 worth spending $2000 on installed? Or should I have someone rebuild my 83 evinrude 115 for $2000. Thanks!
 

Benny1963

Lieutenant
Joined
Sep 17, 2006
Messages
1,476
Re: compression #'s for a 1987 johnson 150

the numbers are a tad low .but they are fairly equal a decarb and running it may bring those numbers up.what kind of numbers are you getting on
your 115
bennyb
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: compression #'s for a 1987 johnson 150

i think with those numbers i would rebuild the 83, at least you will know what you have. paying 2,000 for the 87 may be a rebuild next week. the #'s are too low for me.
 

JB

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Joined
Mar 25, 2001
Messages
45,907
Re: compression #'s for a 1987 johnson 150

I would confirm those numbers with a different guage. I find it hard to believe that 6 cylinders would all go "bad" the same amount at the same time.

Even if a different guage confirms PSI in the 80-85 range I wouldn't schedule a rebuild until after water testing the engine and getting poor performance.

I think the engine is probably healthy.
 
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