my lawnboy 8237 mower stopped self propelling itself this weekend, so
i disassembled the engine and found the drive gear was shredded into
pieces. So i will replace the gear with a new one, no problem. My
question is, what lubricates this part? Is the gearbox supposed to be
reassembled with gearbox oil? If so, how do you get it in there?
Also while I have the engine all apart, should I replace the piston
and rings? When the mower is running it seems quite strong, so what
are your recommendations? Should I just wait until the rings are
completely worn out before replacing?
Are you talking about the gears on the lower end of the engine?
If you have the engine all apart, replace the piston rings, crankshaft
seals, and the reed valves. I would not replace the piston as long as it
looks good. Beings you have it apart you may consider going through the carb
too. A gasket, needle and seat, and float will keep you from tearing it
apart in the near future. Also a new rewind rope and remove and clean the
recoil spring too! None of this will be any easier to repair/replace now as
you have it all apart, and the parts don't cost much either.
Yes, the gears i am talking about are the ones that are driven off the
crankshaft and eventually drive the rear wheels.
I looked at the reed valves, they seem to have been doing their job,
do these wear out that frequently?
I am taking your advice to replace the crankshaft seals.
I wonder if you could tell me how to carefully remove the rings,
assuming the piston is already removed, and put the new ones on. Is a
special tool required? Is there a special grease required when
sliding the piston back in with the new rings?
There is a tool you can buy to help expand the rings to install them, looks
allot like a snap ring pliers. That said I never use one. The rings will
break if you twist them too much so you do need to be careful. When
installing rings I start with the ring end gap placed over the groove the
ring fits into. The Ring will be at an angle over the top of the piston.
Taking both thumbs, slowly spread the ring gap while sliding the rind over
the piston with your fingers.
As far as lube, just a drop or two of two cycle oil on the cylinder wall,
and any bearing surface. Don't overdue it!
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