How to Maintain Your Scag Mower

Scag MowerFrequent and routine maintenance is the best way to keep a machine in top condition and prevent costly issues from arising over the long term. For owners of Scag riding mowers, proper maintenance will ensure reliable functionality and high levels of efficiency.

Maintenance Intervals

There are a number of items to inspect and replace when maintaining a Scag mower and keeping track of all of them can be difficult if only some are done at a time. The best approach to keeping the mower maintained is to follow a consistent schedule. This will ensure that nothing is overlooked and that all equipment is replaced on time.

The primary items in need of replacement are various fluids and filters. Engine oil should be checked after every eight hours of operation and replaced as necessary, although no later than after every 100 hours. The engine oil filter should be replaced every 200 hours. Owners should change the hydraulic oil, the hydraulic oil filter, and the fuel filter at least once a year or after 500 hours of operation.

Additionally, Scag provides a factory maintenance schedule for owners of their riding mowers.

  • Break-In Procedure: Owners are expected to break in their new machinery. Within the first 10 hours of operation, owners must ensure that everything is securely fastened, check the oil level and hoses in the hydraulic system, ensure that all belts remain tight, and inspect the engine oil and filter.
  • Eight Hours: After eight hours of operation, owners must clean the mower, check coolant and oil levels, check the tire pressure, check the condition of the blades, and apply grease to certain fittings.
  • Forty Hours: After 40 hours, owners must inspect their batteries and check the belts again for proper alignment.
  • One Hundred Hours: After 100 hours of operation, owners must apply grease to certain fittings, change the engine oil, clean the air filter, and check the lubricant in the deck’s gearbox.
  • Two Hundred Hours: After 200 hours of operation, owners must change their engine oil filter and check the hydraulic oil level. Apply additional grease to fittings and ensure that all mounting hardware is secure and that all belts and bolts remain secure.
  • Five Hundred Hours: After 500 hours of operation, the mower will need a new fuel filter, hydraulic oil, hydraulic oil filter, deck gearbox lubricant, and coolant if the machine is liquid cooled.

Essential Replacement Parts

Essential replacement parts vary depending upon the maintenance schedule. As described above, owners will eventually require oil filters for the engine and hydraulic system, a fuel filter, and coolant for liquid-cooled machines. Additional parts may be necessary upon inspection, such as new belts or new blades.

Safety Precautions

Before performing any maintenance on any machine, ensure that the machine is not running. Ensure that the ignition switch is in the “Off” position and remove the key from its slot to ensure that it is not inadvertently bumped. For added security, remove the spark plug wire or disconnect the battery. If the machine was recently running, allow it to cool before performing any maintenance.

Before working on the machine, ensure that the parking brake is set and that the machine is on flat, level ground. There should be ample space to walk around the machine. Wear heavy gloves while working around the blades; if inspecting the blades will not be a part of the maintenance, sheathe the blades while you work on the machine.

Before working on the engine, identify which engine your machine utilizes and secure an owner’s manual for that engine. While performing maintenance, do not modify the engine’s governor; over revving the engine can cause permanent and expensive damage to the engine. Use only the oil specified in the manual.

Scag also advises that all maintenance on the hydraulic system be performed by an authorized Scag dealer. Hydraulic fluid is under significant pressure and an unexpected release of fluid can perforate skin and enter the body, resulting in serious medical complications if the fluid is not surgically removed quickly. Keep all body parts away from any holes or slots that eject hydraulic fluid at all times.

Inspect the Mower

Before any maintenance can begin, owners should inspect their mowers. Check all belts and fasteners to ensure that everything is secure. Inspect the blades to for any cracking or deformation and ensure that the blades are sharp. If the blades are cracked or damaged, do not weld or straighten the blades; simply replace them. In addition, owners or maintenance personnel should inspect the machine again after servicing it.

The Hydraulic System

  • Checking Hydraulic Oil: Wipe the area around the cap for the hydraulic reservoir of contaminants and remove the cap. Oil should be at least 3.25 inches from the filler cap. Add 20W50 oil if it is too low, but do not overfill. Replace the cap when done.
  • Changing Hydraulic Oil: Place a container under the drain plug for the hydraulic fluid reservoir and remove the plug. When the system has been drained, replace the plug and refill the reservoir with 20W50. Stop filling when the oil is 3.25 inches from the cap.
  • Changing Hydraulic Oil Filter: Remove the hydraulic oil filter from the bottom of the machine. Consult your manual if you have difficulty locating it. Replace the filter with the new filter. After replacing it, idle the engine for a few minutes and then check the hydraulic oil level.

Engine Oil

  • Checking Engine Oil: Checking the engine oil is simple. Atop the machine is a standard dipstick. Ensure that the volume is correct and that the engine oil is fresh. Signs of contaminants in the oil, like grass or metal fragments, should result in an immediate change in engine oil.
  • Replacing Engine Oil: Place a safe container underneath the oil drain plug and remove the plug. Allow the oil to drain. Once the oil has drained, replace the plug and refill with the appropriate weight oil as described in the engine manual provided with the mower.
  • Changing Engine Oil Filter: The oil filter is usually visible, but Scag mowers use a variety of engines from numerous manufacturers. To identify the location and specific procedure for changing the oil filter on your individual machine, consult the manual for your engine.

Inspecting the Battery

Scag recommends inspecting the battery weekly or after 40 hours of operation. Ensure that the battery is clean and that the terminals are not corroded. If they are, clean the posts with steel wool and a solution of baking soda and water. Keep this solution out of the battery cells.

Inspecting the battery in a Scag mower requires removing the battery cell cap to inspect the electrolyte level, so this step should be done carefully; wear eye protection and gloves while working on the battery and do not perform this procedure near any open flames. Remove the caps and check the electrolyte level. It should be at the bottom of the vent wells. If it is below this amount, fill it with distilled water until the battery is at this level.

After inspecting the electrolyte level, replace the caps and fasten the connectors. Use a light layer of silicone dielectric grease to prevent corrosion. Start the mower to ensure that the battery is fully functional.

Cutter Deck Gearbox

  • Checking Lubricant: Lower the deck to its lowest point and access the check plug on the side of the gearbox. Lubricant should be up to the bottom of the hole. If not, add 80W90 through the check hole until it is. Replace the check plug when finished.
  • Changing Deck Gearbox Lubricant: Place a safe container underneath the gearbox. Locate the drain plug on the gearbox and remove it. Wait until the lubricant is drained. Once it is, replace the drain plug and refill the gearbox with 80W90 through the check plug on the side of the gearbox.

The Blades

Sharp blades are critical to the effectiveness of any mower. Raise the deck to its highest point and raise up the front of the machine slightly to access the blades. If the blades are clean, undamaged and sharp, just ensure that the blade attaching bolt is securely fastened and that the blades are properly balanced. Grease the cutter deck spindle with lithium grease.

If the blades appear to be fine and if you have not noticed any reduction in the effectiveness of the cut, the blades will not require further attention. However, if the blades are dull, they will require sharpening. If the blades are damaged, they must be replaced.

  • Sharpening the Blades: Sharpening the blades can be done with the blades in place. Use a file, not a grinder, as a grinder can damage the blades. Do not change any angles or add a new bevel; simply sharpen the blade.
  • Replacing the Blades: Before removing the blades, secure them to prevent them from rotating. Unscrew the hex nut from the main bolt and remove the blade, bolt and spacer from the shaft. Put the bolt and washer through the new blade, reinstall the spacer, and reinsert the bolt into the spindle shaft. Thread the hex nut back onto the other end of the bolt and torque it to 75 lbs-ft.

Applying Lubrication

Owners must apply chassis and lubrication to a total of 20 parts around the machine. Most areas that involve some metal to metal contact will require attention. Owners should consult their manual for a diagram of which lubricant to apply to which area.

To buy these parts or any other replacement parts, go to Shank’s Lawn Equipment. Shank’s Lawn Equipment has a large inventory of factory original parts and a wide array of factory diagrams, ensuring that you buy the right type of part for your machine. If you are in the Waterfall PA or Wells Tannery PA, area please stop by – to visit with an expert or just to say hi.


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