Hello everyone-

I have repaired many of these 31cc engines in string trimmers and leaf blowers, and most of these were from the 1990's time frame. One thing I always noticed was the reed stop is extremely close to the con rod big end. All had rubbing on the reed stop by the con rod until flakes of chrome came off the reed stop then, more metal was torn from the reed stop, then the engine would lock up from the metal fragments getting into the crank bearing.

I solved this problem by using 2-3 gaskets under the intake block and sealing well with permatex ultra grey. I wonder if this may have contriburted to your rod failure. I found it impossible to remove all the minute metal particles from the bearing when this happened, so a new service crankcase would be installed (along with a new reed assembly, and careful check of the rod bearings). My old service manual for this engine lists some brush cutters models maximum rpm as 8,800, so I feel that the rpm isn't the culprit.

MTD sells an improved crankcase now for ~ 60-70 dollars, that is stronger than the older types, but you'll need the matching flywheel and module as the woodruff key location has changed.MTD-753-04328 (long shaft). Yes, it's not worth the time or money actually, but I really like this engine so I repair them when I can find one. [sm=49_49.gif]