Small Engines (Lawn Mowers, etc.): Hydraulic drive in Bolens ride-on mower, hydrostat, bypass valve

Question
Hi, I have recently bought a used Bolens/Garden Way ride-on mower model number 13042, serial number 130420100487.
Like a previous questioner, my mower loses power and sometimes judders going uphill after half an hour of mowing.
I cannot find a service manual for this machine, so could it be low hydraulic oil, and how do I check it, please?

Answer
There is usually an expansion chamber somewhere on the tractor open it and there should be a line letting you know how full it should be.  Do not overfill because this fluid expands as it heats up and if you put too much in it will leak out.

My suggestion would be to follow the drive linkage from the handle or pedal to the hydrostat.  This should be adjustable.  Adjusted to give full range of motion on the valve in the hydrostat.  Next find the bypass valve this is the valve you open to be able to push the unit.  Remove the linkage open the bypass valve pushed the unit then close the valve manually reattach the linkage being sure you get full closure the valve does not have to be wrench tight it should open and close easily.  Now put the bumper against a wall and with the engine at full speed you should be able to break traction on the tires meaning spin the tires.  If this does not solve the problem and the unit is still under warranty I would suggest contacting your dealer.  If it is behind the Warnke you could purchase a refill kit and rebuild the hydrostat but it would probably be easier and cheaper to replace it.  It will be either Hydro-Gear or Peerless hydrostat.  Both brands are built in the United States and each has a website with information to help troubleshoot the drive system.  I hope this information helps you out and helps you resolve your problem if you need more assistance please contact us.