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2018 Suzuki DF90 lower unit crack not under warranty?

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  • 2018 Suzuki DF90 lower unit crack not under warranty?

    My 2018 has developed a crack just forward of the prop in the lower unit housing. I have absolutely no idea how this happened as there is no evidence of an impact and I also religiously flush the engine and lower unit after each use. I have taken some pictures and sent to the dealer where I bought the engine from and was dismissed that Suzuki doesnt cover corrosion. Um, there is no evidence of corrosion just a crack that appeared due to poor lower unit material quality, casting issue, etc.

    So, should I be surprised at this answer or pursue this further?

    I am also experiencing an intermittent issue of what I believe is the rev limiter as I dont think that the signal that the shifter is in forward is being sent to the ECM. I am chasing down this issue as well. I have checked the fuel, compression, replaced plugs, etc and everything looks great there so i think the lower unit and the "rev limiter" are connected- not sure. Also, where is this alleged "white" wire from the shifter of the enging to the ECM?

    THanks SO much
    Attached Files

  • #2
    Do you have freezing cold conditions in your area? If so is it possible that the crack was caused by water freezing in that lower unit area.

    It could also be due to water getting into the gearbox and causing corrosion internally to bearing carriers which then expands and can cause cracks not unlike that one. Or, water ingress in the gearbox that freezes and causes cracking if the casing.

    Not saying anything about your issue, just be aware however that they will have seen just about everything, and will be able to tell on inspection if the issue is one due to a manufacturing defect or due to another cause that is not covered by warranty.

    To me, I would want them to personally inspect it and not make up their minds based in a couple of photos. I would make an appointment and take it to the dealer for inspection while I was present.

    If there is truly no user based reason for the fault, then try to pursue the issue with the dealer, they don’t decide warranty claims, Suzuki does, so stay calm, explain the circumstances fully, and ask that an inspection report be sent to Suzuki for warranty assessment. If thats already been done and rejected, ask for written reasons, see what it says, and you may then think about asking for a review on site by the regional Suzuki rep.


    • #3
      Re the white wire.

      The rev limiter and the crack in the lower unit aren’t connected. The rev limiter prevents the engine from over reving at WOT. My rev limiter kicks in at 6300RPMs. Your shift position sensor will prevent the engine from reving above 3000RPM while in neutral. If your engine won’t turn over then perhaps your neutral safety switch is giving you grief.


      • #4
        Thanks so much Moonlighter and Murray!

        Moonlighter- I live in North Fl and we havent had any freezing weather for the last 2 years. Plus the engine is always is stored vertically and the bow up so would think that most of the water should have drained out of the prop. I am workig with a dealer now to take a look at the unit and hope to hear something next week.

        Murray- I have SMG4 digital instruments and when I shift from N to F or R there the SMG4 goes from F to a blank display. Would that indicate that the white wire shifter signal to the ECM is not being sent? I also had an friend with a computer diagnostic hooked to the engine and we couldnt see where the engine switched from N to F, etc. I could see that the number of times the gear was changed and every time I shifted the number incremented. I just dont know if the diagnostic shows which gear you are in to compare against the SMG4 (which doesnt show the gear now...)



        • #5
          Sorry, can’t help you with the digital stuff. Perhaps Moonlighter can offer some advice. My setup is when you shift it to forward the boat moves forward likewise for reverse. If both those conditions are met then it’s working. I don’t think the white wire comes into play with shifting gears and the corresponding SMG4 F-N-R display. I could be wrong.


          • #6
            The DF90A has a neutral throttle switch (NTS) same as most other non FBW engines. Located on the starboard side of the engine on the gear linkages.

            So SMG should show engine position N when its out of gear. As should SDS computer.

            You may have a faulty NTS - if the ecu does not see the “in gear” signal when the engine is put into forward or reverse, it will restrict rpm to about 3000. If you push the throttle hard forward in this condition, the engine will miss and fart at 3000rpm like a race car engine does when its on the pit lane speed limiter.

            These switches can have intermittent faults, they can just get a bit stuck at times. Or they can get a physical break or just be loose. Need to look at it to see whats happening. Not hard to replace or very expensive to get the new part.