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:unsure: Hi, I removed my engine and sent it out to have some service done that included replacing the sprage clutch. I was quoted reasonable price, upon tear down I was told I needed a new free wheel gear, price jumped a lot. Teardown completed, everything checked out within specs. Upon reasembly I was told the crank & cam were binding, told it was a crack in the case. When I requested details on the crack I was told that the die check reveiled a probible crack at the mag end of the case and that dressing the fretting on the case haves caused the binding and the suspected crack and the case was unservicable, cost to repair skyrocketed. The engine has a light case with 1000 hours on it and was just hard to start, wear on internal parts was minimal, with no binding at all until teardown and reasembly My question is does this sound reasonable? Every rotax repair center teck adviser I contacted said they had never herd of this happening and they felt that a mistake was made by the teck working on it. Anyone ever have this problem or hear of it hapening? I feel like I've been had, but don't know for sure, and don't know what, if anything, I can or should do about this. Any thoughts?
  • Re: crank and cam binding

    by » 11 years ago


    As far as the binding it can happen if the case halves were overdressed by an inexperienced tech. This is easy to do as the tendency is to dress out any visible fretting without realizing how critical the tolerances are.
    It is also possible the technician was correct and the case was beyond the wear limit even without overdressing the fretted areas. The fretting is caused by crankshaft wobble and/or rough running vibration. The new style crankcase has a much higher clamping force so this is not such a problem.
    Rob

  • Re: crank and cam binding

    by » 11 years ago


    Thanks Rob, The tech that started the job did just what you said. Except for the unexperianced part, he said that when he dressed out the fretting that the tolerances became too close. He works for a major rotax rebuild center and at first said it was because of case cracks (none present), he later talked to the us factory service rep and that rep told him that the case halves got dressed down too much. We are in the process of trying to address this in a fair manner that we can both live with as far as what the repair with new case halves will cost me.

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