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2 stroke spark plug diagnosis needed

aboveboredabovebored Posts: 1,342 Officer
I found this whitish crusty buildup on cylinder #1's spark plug electrodes. The other 5 plugs look normal. The motor is a 1996 Johnson 175. It runs good, idles good, has good compression on all cylinders, This plug has less than 100 hours of running time. Sorry pics are out of focus, Any ideas regarding the cause would be greatly appreciated,


  • FishinjeffFishinjeff Posts: 56 Deckhand
    Looks like burnt oil deposits.  Does it have a oil injection?  2 stroke?
  • aboveboredabovebored Posts: 1,342 Officer
    Its a carbureted 2 stroke with premixed oil/fuel. I also thought it was "ash"  deposits, but why only one cylinder with this problem? I always use quality oil and fresh gas with a good filter.
  • SloughSlough S.w. Ga./ St. JamesPosts: 5,672 Admiral
    May not have enough spark ( plug, wire or coil). I would try a new plug first and maybe swap coils with another cylinder.
    I didn't say it was your fault, I said I was blaming you
  • aboveboredabovebored Posts: 1,342 Officer
    Thanks for the input guys. After more research I discovered that the buildup on the plug is actually salt. Evidently, there is a known defect in the block casting from the early years of the ocean runner/pro series 60 degree v6 motors which caused a crack in the block, allowing water intrusion into the #1 cylinder. I did read that someone successfully repaired this by accessing the crack under the water cooled voltage regulator and filled it with JB weld, If anyone has any additional information about this I would be very interested to learn more. Thanks again.
  • aboveboredabovebored Posts: 1,342 Officer
    Also, the original year I posted was incorrect, its not a 1996 but a 1992 in fact (before they resolved the problem apparently)
  • livebaitlivebait Posts: 793 Officer
    If memory serves me right the 1992 175 had o-rings at each cylinder rather than a head gasket. Sounds like the upper ring is a bit shaky. Part number 0335523.
  • livebaitlivebait Posts: 793 Officer
    what was the problem or still researching?
  • aboveboredabovebored Posts: 1,342 Officer
       After getting steered in the right direction it appears the o rings have seen better days. #1 was was deformed and crusty. This motor has no head gasket just o rings, I changed all 3. The cylinder walls are still smooth,,hopefully caught it in time. After finding out about the defective blocks I was really starting to get bummed out so I was really quite relieved to find the shaky o ring. Thanks livebait.
  • FletchFletch Merritt Island, FLPosts: 2,546 Moderator
    Yep, white like that usually means water in the mix. I had a 175 Oceanrunner back in the day that had the defect. All OMC was going to offer was a new block (just the block). Didn't want to do the re-build route. Fuzzy memory but I think I wound up getting a short block from them but still had to come out of pocket a fair amount. Not as much as new but not free either.
    "Ninety percent I'll spend on good times, women and Irish whiskey. The other ten percent, I'll probably waste..."
    -- Tug McGraw on getting a raise

    Get Down Fishing Charters - Port Canaveral, Florida
  • livebaitlivebait Posts: 793 Officer
    if that motor has been running since 1992 it doesn't have a factory defect block. But I do remember the 175 "FastStrikes" were an accident waiting to happen. Made good money back in the day on them. Fast as the devil, thirsty as the devil, and subject to let go over 5,000 rpm.
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