Scag Patriot Zero-Turn Rider Troubleshooting and Maintenance

Want to get the most out of your Scag Patriot mower? This guide will walk you through maintenance tasks and help you solve common problems with your ZTR.

Maintenance Schedule

First 10 hours of use: Check hardware for tightness and belts for alignment. Check the hydraulic oil level.

Every 8 hours: Check engine oil level, safety interlock system and tire pressure, and inspect hydraulic hoses for leaks.

Every 20 hours: Change engine oil and filter.

Every 40 hours: Check and clean the battery and battery posts. Inspect the pump drive belt.

Every 100 hours: Check the fuel lines for leaks. Replace the hydraulic fluid and filters. Clean the air filter.

First 120 hours: Change the hydraulic fluid.

Every 200 hours: Check all hardware for tightness.

Every 400 hours or annually: Replace the fuel filter and adjust the PTO clutch.

Hydraulic Fluid

When the mower is cold, the level can be checked by looking at the sight glass on the side of the expansion tank located to the left of the motor. Milky fluid is contaminated with water, and black fluid has overheated. If either are present, the fluid should be replaced. The system is designed to use 20w50 oil.

To change the fluid and filters:

  1. Park the mower on a level surface
  2. Remove the filter guards from the filters, located next to both rear axles. There are three screws in each one.
  3. Place a drain pan underneath the filters. Remove the cap from the expansion tank, then unscrew the filters.
  4. Once the system has drained, install new filters by hand, tightening 3/4 turn after the gasket contacts the filter base.
  5. Reinstall the filter guards, torquing the bolts to 65 in/lbs.
  6. Remove the top port plugs, located above the filters. Add oil to the expansion tank until it starts flowing out of the port plugs. It should hold about 5 quarts.
  7. Tighten the plugs to 180 in/lbs. and screw in the expansion tank cap.
  8. Lift the rear of the mower onto jack stands and move the dump valve control levers, located on the frame to the left and right of the motor, to the “freewheel” position.
  9. Sit in the seat and start the engine. At 1/2 throttle, push the lever fully forward and reverse 5-6 times. Repeat with the dump valve levers in “drive.” This should purge any air in the system.

Engine Oil, Air Filter and Battery

Refer to the engine and battery manuals included with your mower. Running changes mean maintenance methods change constantly.


To inspect the blades, raise the deck to its highest position.

To sharpen a blade, use a file, cutting across the top of the blade edge. Maintain a 30 degree cutting angle.

To replace a blade, use a Blade Buddy tool to keep it fixed in place. Loosen the blade bolt, then slide off the bolt, lock washer, flat washer and blade. Reassemble in reverse order with the blade’s lift wing pointed up. Torque the bolt to 75 ft-lbs.


To check the clutch adjustment, shut off the mower and insert a 0.015 inch feeler gauge into the three inspection windows around the clutch body; the gauge should just touch the armature and rotor. If the gap is too big or small, adjust the distance using the three nuts on the face of the clutch.


If addressing the causes listed below doesn’t solve the problem, you should have your mower looked at by a service center.

Occasional blades of uncut grass:

  • Increase engine speed
  • Move slower while cutting to let the deck keep up
  • Allow wet grass to dry out
  • Mower blades are dull or weren’t sharpened correctly
  • The deck is plugged up and needs to be cleaned
  • The drive belts are slipping and need to be adjusted

Strips of uncut grass between cutting paths:

  • Increase the overlap between passes

Strips of uncut grass in cutting path:

  • The blades are dull, bent, damaged or incorrectly sharpened
  • Increase engine speed
  • The drive belts are slipping and need to be adjusted
  • Move slower while cutting to let the deck keep up
  • The deck is plugged up and needs to be cleaned

Uneven cut on flat ground:

  • Blade was installed upside-down
  • Blade is worn
  • The deck is plugged up and needs to be cleaned
  • Deck pitch and level needs to be reduced

Uneven cut on uneven ground:

  • Reduce mowing speed
  • Raise deck height
  • Change direction of cut

Sloping ridge across mowing path:

  • Make sure tire pressure is equal
  • Check that the deck is level


  • Check tire pressure
  • Move slower while mowing
  • Raise deck
  • Let the grass dry out before mowing

Ridge in center of cutting path:

  • Blades mounted unevenly
  • Blade is bent

Where to Buy Parts and Accessories for the Scag Patriot

Whether you need a Blade Buddy tool or major components, you can get them from Shanks Lawn Equipment. Their shop is located at 4900 Molly Pitcher Highway in Chambersburg, just off route 11. To get there from I-81, take Exit 10 to Marion. Not in the area? Visit them online at

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