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Honda 31cc M4 Engine Bearing Failure

Discussion in 'Mechanic and Repair' started by brudot, Apr 30, 2006.

  1. brudot

    brudot LawnSite Member
    from CT
    Messages: 57

    I have this engine on a brush saw/trimmer and the crankshaft bearing on the flywheel end failed after about 50 hours. Has anyone had a similar experience? Oil is always checked and changed.
  2. khouse

    khouse LawnSite Bronze Member
    Messages: 1,465

    What type and ratio of fuel mix are you running? Also if your tool head is not ballanced or running smooth can put an extra strain on the crank bearing or crank itself to the point that the crank could even break. Do you have teeth missing on you cutter?
  3. AAELI

    AAELI LawnSite Senior Member
    Messages: 360

    Is this the Honda BCGX31 engine? If so, then the failure at only 50 hours is covered under warranty. I am assuming of course that the unit is less than 3 years old. Has the bearing seized or is it running rough? I have had several come into my shop with this problem but all were high time units often run without airfilters which allow dirt to enter the oil sump and subsequently cause bearing failure. If run under heavy loads at wide open throttle/low rpm then it could be that the oil 'cooked' due to inadequate cooling from the slow speed. This engine has been pretty reliable for many. Check with your dealer.
  4. ed2hess

    ed2hess LawnSite Fanatic
    Messages: 14,292

    Is this a four stroke that is lubed by crankcase of oil rather than the 2 cycle oil mix??
  5. AAELI

    AAELI LawnSite Senior Member
    Messages: 360

    The Honda 31cc Mini-4 stroke uses 30W oil in the sump. It is not a 2 cycle engine. I often have these turned in for repair with 2 stroke oil in the sump. Some people have a hard time adjusting to the 4 stroke trimmer/brushcutters.

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