82 merc 115 hp compression

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meggy73123

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Jan 8, 2012
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does anybody know what my compression should be on a 115 hp merc. just bought it 2 months ago never had it in the water but did a compression test on it last night and top 5 cylinders are 130 psi and the bottom is 128 is it good or should it be above 130 ? thanks
 
Y

Yarb

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Oct 5, 2009
Messages
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Re: 82 merc 115 hp compression

I ran a compression test on my 1984 115 Merc this afternoon.
1 to 6= 145, 148, 145, 143, 143, 145
The old "tower of power" motors are hard to beat. I had the powerhead replaced in 2004, Katrina came in 2005 and washed away everything we owned including my bass boat. I found it upside down in a oak tree three days later. I thought it would never run again. I flushed it out with fresh water and washed all the electrical components with soap and water, did a quick clean of the carbs, hooked a battery to it and cranked and cranked and cranked. Finally it hit on one or two cylinders and the rest came in after a few minutes. I let it run on the hose with double oil for a couple of hours. The old Merc are hard to beat. I put in the water last weekend for the first time in 6 years. It still runs great.

Yarb
 
J

justchecking

Petty Officer 2nd Class
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Oct 1, 2010
Messages
152
Re: 82 merc 115 hp compression

Mine without squirting oil in the cylinders are about 110 in all 6. Still runs GREAT.
 
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Chris1956

Honorary Supreme Mariner
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Mar 25, 2004
Messages
29,288
Re: 82 merc 115 hp compression

OK, Remember that compression gauges may not be accurate, but they are usually reliable. So if you get close (+/-10%)readings on all cylinders, the motor is fine. The magnitude of the reading is not important, as the gauge's calibration is probably not the same as another poster's gauge..
 
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