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evinrude 115hp 1996 crossflow compression issue

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  • evinrude 115hp 1996 crossflow compression issue

    My son replaced piston kit on my boat. When he put it back together every cylinder had 60lbs of pressure and will not start. I just got the boat back today (he was deployed for the Navy). I suspect that since he order the standard piston kit that there may be an issue with the piston or ring sizes since all the cylinders are the same.

    Where do you recommend I start? Since I had tasked my son, it is safe to assume that I am somewhat overwhelmed with tearing the engine back apart. I figure google, forums, clymer manual, and lots and lots of pictures.

  • #2
    Without some facts it is hard to say !----Was the motor " rebuilt " once and now he put standard pistons in ?-------Pull heads off.--------Have a look , post pictures.-----Measure cylinder bores.------Post any piston ID numbers.-------This should be easy to figure out !

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    • #3
      When I bought the boat, I was told that cylinder 1 had some work. Not sure what extent that was. I've been having the boat for a few years now. Can I measure cylinder bores with just the heads off or does the pistons need to come out? If I measure bore and piston, how can I tell if correct piston and what rings need to be used?

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      • #4
        Pistons will have numbers.-----Measure the bore with heads off.----Post the information !

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        • #5
          Click image for larger version

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ID:	10831537 Sorry about the delay. I had to get the tools. Also, I disassembled the crank because piston 1 actually had side to side movement. Numbers show that someone must have bored it out with larger piston.

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          • #6
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            • #7
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              • #8
                Your cylinders are a standard bore.-----And the pistons shown are also for a standard bore !----Even new pistons are tapered with about 0.012" clearance at the rings and about 0.003 " at the skirt.

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                • #9
                  So, the rings and pistons are good to go? What about cylinder one? 3.518 is a big difference to the others at 3.499

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                  • #10
                    That ( #1 ) cylinder was bored / honed out.----What piston was in that cylinder ?-----If that 88.79 mm piston was in the # 1 cylinder it was a big mistake.-------Where / what pistons did you measure at 88.30 mm , where they new or used ?
                    Last edited by racerone; February 12th, 2020, 03:36 PM.

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                    • #11
                      so, I think all the pistons are standard size. They are all new. I may have not been measuring the pistons correctly. The pictures that I posted are the numbers that are stamped. one had L38 G and the rest had L39 G. The rest of the numbers on the pistons are the same. Same kit.

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                      • #12
                        L38G may identify the inspector / mold / production batch at the factory.--------After looking those numbers over again I am confused.----Piston #1 you say 88.79 +0.95 and others are 88.79 +0.095.----Picture of all 4 pistons ??
                        Last edited by racerone; February 12th, 2020, 06:39 PM.

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                        • #13
                          Looks like someone honed the chit out of cylinder now it almost .020 over size...No MFG I deal with carries a .015 crossflow piston. Those are WSM /ProMarine pistons and only come in .010'a (.010/.020/.030.040)
                          When in doubt,Trim it out!!!
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                          • #14
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                            • #15
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                              Conclusion ------One cylinder bored out to 0.020" and then a standard piston installed.-------Fit a ring in #1 cylinder.-----Measure ring gap.----Fit same ring in #2 cylinder and measure gap.------And what else was missed during this " rebuild "

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