jay_merrill
Vice Admiral
- Joined
- Dec 5, 2007
- Messages
- 5,653
I have an old JohnyRude that is giving me strange compression test readings.
First, the motor appears to be an 85hp Evinrude powerhead, sitting on a Johnson 135 midsection and gearcase. It was a "Katrina motor," which sat in water to a point just below the powerhead, for several weeks, until flood waters receded. I believe that the height of the water peaked as just described and then dropped slowly, over the time period involved. There does not seem to be any indication that the powerhead was ever submerged.
I finally got around to doing a compression check on it, this afternoon. The flywheel rotates freely by hand and gives indications of compression, as each cylinder reaches "upstroke." The problem is that I got readings of about 30 psi on all four cylinders, consistently. This ocurred while using the starter to "turn the motor over." Although I did most of the testing with all of the spark plugs out, because of a marginal battery, I tried a couple of cylinders with the plugs back in and got the same results.
All of the readings were consistent - about 30 psi on all four, every time. My first thought, of course, was the compression tester, but I use it frequently on other outboards and have never had a problem with it. It was also screwed in all the way and I wasn't bottoming out on the piston domes.
Has anyone else ever gotten compression readings this low and had them be so even? Any thoughts on what might be going on?
PS: Does anyone know where the welsh plug with the model/serial #s are on this motor? I've looked and can't find it. It has a single powerpack on the flatback and the coil rack running across the top/rear portion of the powerhead. There is also a terminal block for the wiring on the port side, next to the coil rack. Could it be under any of that stuff?
???
First, the motor appears to be an 85hp Evinrude powerhead, sitting on a Johnson 135 midsection and gearcase. It was a "Katrina motor," which sat in water to a point just below the powerhead, for several weeks, until flood waters receded. I believe that the height of the water peaked as just described and then dropped slowly, over the time period involved. There does not seem to be any indication that the powerhead was ever submerged.
I finally got around to doing a compression check on it, this afternoon. The flywheel rotates freely by hand and gives indications of compression, as each cylinder reaches "upstroke." The problem is that I got readings of about 30 psi on all four cylinders, consistently. This ocurred while using the starter to "turn the motor over." Although I did most of the testing with all of the spark plugs out, because of a marginal battery, I tried a couple of cylinders with the plugs back in and got the same results.
All of the readings were consistent - about 30 psi on all four, every time. My first thought, of course, was the compression tester, but I use it frequently on other outboards and have never had a problem with it. It was also screwed in all the way and I wasn't bottoming out on the piston domes.
Has anyone else ever gotten compression readings this low and had them be so even? Any thoughts on what might be going on?
PS: Does anyone know where the welsh plug with the model/serial #s are on this motor? I've looked and can't find it. It has a single powerpack on the flatback and the coil rack running across the top/rear portion of the powerhead. There is also a terminal block for the wiring on the port side, next to the coil rack. Could it be under any of that stuff?
???
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