While SCAG manufactures top-of-the-line lawn mowers, just like any other brand mower, they will develop problems over time.
Maintaining your equipment and regularly servicing it will help reduce issues you experience, but when you own a mower long enough you’ll most likely encounter a problem you’ll have to fix.
To keep your mower running at its best, regularly clean your mower, check the engine oil and hydraulic oil, clean the air filter, sharpen the blades, and scrape the deck. Perform routine oil changes as required for your SCAG mower.
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Follow all safety instructions provided in your equipment operator’s manual before diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.
Common SCAG Lawn Mower Problems & Solutions
Here is a quick summary of problems that can develop in your SCAG mower. Follow the links to more in-depth articles for detailed information on diagnosing and repairing your mower.
1. Won’t Start
Your SCAG mower can have problems starting when it isn’t getting the spark, fuel, or air required by the engine to form combustion in the cylinder. Check for an air restriction caused by a plugged air filter or incorrect choke setting.
Running old gas through your mower is a culprit that can cause problems in the fuel system. Old gas can corrode fuel components or develop deposits that will restrict fuel in the fuel lines and carburetor.
Other problems that can cause your mower not to start can be a bad spark plug or electrical issues like a bad battery, corroded wiring, a bad switch, or a faulty charging system.
Detailed information can be found at:
15 Reasons Your SCAG Lawn Mower Won’t Start
| Cause | Reason for Problem | Solution |
| No gas in the fuel tank | Fuel tank is empty | Fill with fresh fuel |
| Bad or old fuel | Fuel breaks down overtime making your fuel less efficient and prone to clogging the fuel system | Drain the fuel tank and fill it with fresh fuel. Use a fuel additive like Sea Foam to stabilize the fuel and assist with cleaning the fuel system. Use the right fuel. |
| Faulty or clogged fuel cap | The vent in the cap or other type of vent off of your fuel tank can get clogged causing the fuel tank to form a vacuum restricting fuel flow | Replace a clogged fuel tank vent. |
| Bad spark plug | Excessively dirty or broken spark plug; bad connection; not gapped correctly | Replace with a new spark plug, secure connections, and ensure it is gapped to manufacturer specifications |
| Plugged air filter | Dirt and grass can plug the air filter preventing airflow | Remove the filter and clean it. Replace the filter if it is in bad condition. |
| Plugged fuel filter | A dirty fuel filter will restrict fuel flow | Replace the fuel filter |
| Bad fuel pump | A failed or leaking fuel pump will no longer draw fuel from the tank to move it to the carburetor. | Replace the fuel pump |
| Blocked fuel lines | Bad fuel deposits and dirt can build up and clog the fuel lines preventing the engine from getting the required fuel | Use a carb cleaner and compressed air to clear the clog out of the fuel line. Replace the line if necessary. |
| Dirty carburetor | The carburetor can become dirty and clogged due to bad fuel and ethanol deposits preventing fuel flow | Clean the components making up the carburetor. Replace if needed. |
| Bad battery or loose & dirty terminals | A dead battery, loose cables, or corroded terminals can cause starting problems | Charge your battery and replace it if it won’t hold a charge. Make sure your cables are tight and clean the corrosion from terminals. |
| Bad safety switch | Safety switches are a safety measure that exists to prevent your mower from starting in certain situations. When a switch fails, your mower may not start. | Test and replace faulty safety switch |
| Bad ignition switch or coil | Your mower will not start when either the ignition switch or coil is bad | Test and replace a bad switch |
2. Starts Then Dies
You may be able to get your SCAG mower to start, but after running for a while, it just quits and shuts down. Many of the problems that prevent a lawn mower from starting can also be the reason it dies after it starts and runs.
In addition to checking the fuel, air, and spark problems addressed earlier, look for a faulty ignition coil; an incorrect engine oil level; dirty or broke cooling fins; or a clogged mower deck.
Detailed information can be found at:
Your SCAG Lawn Mower Starts Then Dies: SOLVED!
| Cause | Reason for Problem | Solution |
| Bad fuel | Fuel breaks down overtime making your fuel less efficient and prone to clogging the fuel system and engine damage | Drain the fuel tank and fill it with fresh fuel. Use a fuel additive like Sea Foam to stabilize the fuel and assist with cleaning the fuel system |
| Plugged air filter | Dirt and grass can plug the air filter preventing airflow | Remove the filter and clean it. Replace the filter if it is in bad condition. |
| Dirty or broken cooling fins | Cooling fins get packed with dirt, oil, and grass not allowing air to effectively cool the engine block | Replace broken fins and clean the cooling fins. |
| Clogged fuel lines or filter | Bad fuel deposits and dirt can build up and clog the fuel lines preventing the engine from getting the required fuel | Use a carb cleaner and compressed air to clear the clog out of the fuel line. Replace a plugged fuel filter. |
| Dirty carburetor | The carburetor can become dirty and clogged due to bad fuel and ethanol deposits preventing fuel flow | Clean all components making up the carburetor. Replace if needed. |
| Too Much or Too Little Engine Oil | Too much engine oil increases pressure in the crankcase causing it to overheat and die. Too little oil doesn’t provide the lubrication parts require causing it to overheat and shut down. | Correct your engine oil. Contact a small engine mechanic when this doesn’t correct your problem. You may have developed a significant engine problem. |
| Bad Spark Plug | Dirty or damaged spark plug causes the plug to foul out and cause intermittent running problems. | Clean or replace spark plugs if needed. Ensure spark plug wires are securely attached and the plug is gapped correctly. |
| Faulty Ignition Coil | Windings on the coil can separate and short out on a bad ignition coil | Check for a break in the continuity using an ohm meter and replace is found bad |
| Choke is in the Wrong Position | A choke is used for cold starts. The choke can cause your engine to shut off when it continues to restrict airflow after the engine warms. | Make sure the choke is in the correct position. |
| Bad Fuel Tank Vent | Gas tanks require vents for air to pass through. When the vents get plugged, the fuel tank will cause fuel restrictions. | Replace a fuel tank vent that no longer vents. |
| Clogged Mower Deck | Clogged mower deck causes a strain on the engine causing it to work hard and possibly shut down | Periodically scrape your mower deck to keep it clean |
3. Mower is Smoking
Your lawn mower may begin smoking white, black or blue smoke. While smoke coming from your SCAG mower can indicate you have a significant problem with your mower, it may also not be too bad.
A smoking mower must be addressed right away so minor problems don’t develop into large ones. Stop running the mower once you see smoke and try to find the cause.
Some minor problems to be checked are a plugged air filter, too much oil in the crankcase, or a bad engine gasket.
If you find one of these issues, replace the air filter, correct the crankcase level and replace the gasket. Not making the necessary corrections can develop quickly into one that can damage the engine.
Other more serious items to look for are a low engine oil level or internal engine problems. These are more serious problems that require a small engine mechanic to perform tests to accurately diagnose and perform necessary repairs.
Detailed information can be found at:
Your SCAG Lawn Mower is Blowering White, Blue or Black Smoke
| Cause | Reason for Problem | Solution |
| Plugged air filter | Dirt and grass can plug the air filter preventing airflow | Remove the filter and clean it. Replace the filter if it is in bad condition. |
| Too much oil in the crankcase | Excessive oil can cause pressure to build in the engine allowing oil to get into the cylinder through the valve train | Drain a little engine oil until it is at the manufacturer’s recommended oil level. |
| Engine oil level is too low | Lack of oil can increase friction in your engine causing extreme heat. | Bring to a small engine repair shop to inspect engine damage. You can try adding oil, but it is often too late to fix your engine problem. |
| Internal problems including the piston ring, valve train, or engine gasket | Internal engine problems can have a detrimental effect on your mower if they are not caught soon enough and fixed. | Bring your SCAG mower to your local small engine repair shop for troubleshooting |
4. Weak Hydrostatic Transmission
A hydrostatic transmission on a SCAG lawn mower can feel weak from the use of a bad hydraulic belt or pulley. Old hydraulic oil or not having enough oil in the hydraulic tank can also result in a lack of power from the transmission.
| Cause | Reason for Problem | Solution |
| Bad drive belt | A bad drive belt can cause your pump not to work efficiently | Replace a frayed, cracked or worn belt |
| Bad tensioner pulley | When a tensioner pulley fails, it fails to keep tension on the drive belt | Replace the pulley and grease the tensioner arm |
| Low or old hydraulic oil | Low or old hydraulic oil can fail to lubricate the hydraulic system causing your hydraulic system to seem weak | Change your hydraulic oil at regular intervals as recommended by SCAG. Check your hydraulic oil periodically to ensure your hydraulic fluid is full. |
5. Won’t Drive Straight or Steer Correctly
Several items can affect your SCAG mower’s steering including incorrect tire pressures and worn steering dampers. It is good to check the tracking on your mower.
When the unit is not tracked correctly, your mower can veer off to one side and not drive straight.
| Cause | Reason for Problem | Solution |
| Incorrect tire pressure | Unequal tire pressure can cause your mower to pull to one side. | Check tire pressures and keep them filled to the manufacturer’s spec. Tires on each side of your mower require equal pressure. |
| Bad dampers on zero turn | Bad dampers will cause your mower to jerk to one side when moving forward | Replace with a new damper |
| Tracking adjustment needed on zero turn | When one tire is moving faster than the other, your mower can pull to one side | Adjust the speed adjustment bolt to change the rotation speed of the tire. Refer to your owner’s manual. |
6. Mower Won’t Move
Before you check anything on your SCAG mower, first check to drive bypass valves are not the cause of your moving problem. These are valves located at the rear of your mower that disengages the hydros so you can manually push the mower.
When these valves are bypassed, the mower will free-roll, but will not drive. Make sure the bypass valves are in the operating position.
Once you confirm the bypass valves are not the problem, check for a bad drive belt, broken tensioner spring, or worn tensioner pulley.
A problem in your hydraulic system where the fluid is hot, at a low level, or air is caught in the system can cause your mower to move slowly or not move at all.
Detailed information can be found at:
9 Reasons Your Mower Won’t Move or Go Forward
| Cause | Reason for Problem | Solution |
| Drive release lever in the wrong position | The drive release arms allow hydrostatic mowers to roll freely | The drive-release arms must be in the operating position. |
| Drive pump belt is worn | The mower won’t move if your drive belt has fallen off. It could also not move if the belt is worn. | Replace a worn or cracked belt. Make sure the belt is securely around the pulleys. |
| Bad tensioner pulley | The bearing in the tensioner pulley can fail | Replace the tensioner pulley |
| Missing idler arm spring | If the idler arm spring breaks or goes missing, it can no longer place tension on the drive belt | Replace the broken or missing spring |
| Low or old hydraulic oil | Low or old hydraulic oil can fail to lubricate the hydraulic system causing your hydraulic system to seem weak | Change your hydraulic oil at regular intervals as recommended by SCAG. Check your hydraulic oil periodically to ensure your hydraulic fluid is full. |
| Hot hydraulic fluid | Hot hydraulic fluid can be a sign of damage to your hydrostatic transmission system | Let your hydraulic oil cool. If you find your mower runs fine when it is cold, but becomes weak when the hydraulic system gets hot, have your mower checked at your local SCAG dealership. |
| Air in the hydraulic system | Air must be bled from the hydraulic system after changing your hydraulic fluid or the mower will not be able to move at normal speeds | Follow SCAG’s procedures for changing the hydraulic fluid and bleeding air from the system as outlined in your owner’s manual. |
7. Vibrating and Shaking
Vibration in a mower can be caused by something as small as a wood chip or other debris getting lodged in the mower.
It can also be due to loose hardware, the ball bearing failing in the clutch, loose engine mounting bolts, or worn mower components.
Detailed information can be found at:
This is Why Your SCAG Lawn Mower is Vibrating & Shaking
| Cause | Reason for Problem | Solution |
| Loose or missing engine mounting bolts | Engine bolts are used to reduce the vibration of the mower when the engine is running | Secure engine bolts and replace any missing bolts |
| Clutch is bad | When there is bearing failure and it falls out of the clutch it can cause vibration. | Replace the clutch |
| Unbalanced or damaged mower blades | Damaged and unbalanced blades can send a vibration through your mower. Blades must be balanced before installing | Replace any damaged blades and make sure they are balanced. |
| Material wrapped around the blade spindle | Foreign materials like string or long weeds can get wrapped around your blade shaft causing vibration | Remove all debris and items wrapped around the blade shaft. Check for spindle damage. |
| Bad spindle housing bearings | Vibration can be caused by a bad bearing in the spindle housing. | Replace the bearing in the spindle housing or replace the whole spindle housing assembly |
| Worn pulleys or deck belt | Check deck belt and pulleys for wearing of the belt and bearing failure in the pulleys | Replace any damaged or worn belts and pulleys |
| Debris lodged in mower | The smallest little things can cause your SCAG to excessively vibrate. Check over your mower for debris stuck in the deck or mower. Don’t overlook the small stuff. | Check over your mower deck and mower for any place small items can be stuck in your mower. Remove these foreign materials. |
8. Bad or Uneven Cut
One of the main reasons you invested in your SCAG mower is for its nice cut. It’s disappointing when the mower begins to fail to give you the cut you expect.
To narrow down the cause of your bad or uneven cut, first, start by checking the tire pressures. Something as simple as a low tire will give you a bad cut because the deck will no longer sit level.
Once you have ruled out the tire pressures being wrong, you’ll need to look at your deck. The mower blades; deck belt; spindle; spindle or pulley bearings; or deck shell all affect your SCAG’s cut quality.
Detailed information can be found at:
Reasons Your SCAG Lawn Mower Has a Bad or Uneven Cut
| Worn mower blade | Uneven tire pressures | Engine speed is too low |
| Bent mower blade | Unleveled mower deck | Ground speed is too fast |
| Blade installed wrong | Bent blade spindle or spindle bearing | Damaged deck shell |
| Clogged Mower Deck | Worn deck pulleys or belt | Operator error |
9. Leaking Gas
Oftentimes, you notice you have a fuel leak when you see a small puddle on the ground. Other times you will only smell a strong gas odor in the air because the leaked gas has evaporated leaving no other signs behind.
A fuel leak from your SCAG mower may come from the carburetor due to a failed gasket or stuck float. It can also leak from a fuel filter, fuel shut-off valve, gas cap, fuel lines, or fuel pump.
Detailed information can be found at:
Find Out Where Your SCAG Lawn Mower is Leaking Gas
| Cause | Reason for Problem | Solution |
| Dirty of Failed Carburetor | The carburetor can collect a buildup of substances remaining from old gas that can cause blockages or parts failures resulting in a leak | Clean the carburetor and replace any damaged parts |
| Old Fuel Filter | Filter can become soft and degrade from old fuel | Replace fuel filter |
| Bad Fuel Pump | The pump can wear and deteriorate over time and may begin leaking at the seams | Replace the fuel pump |
| Bad Fuel Tank Seams | A poly tank can leak at the seams of the tank | Replace the fuel tank. |
| Bad Fuel Shut-Off Valve | Shut-off valves are prone to leaking with time | Replace the shut-off valve |
| Cracked or Punctures Fuel Lines | Rubber fuel lines become dry and cracked causing gas to leak. They can also be punctured by a foreign object or the clamps used on the lines. | Replace the fuel lines |
| Bad Seal in the Gas Cap | The gas cap seal can fail and no longer seal allowing gas to splash out of the fuel tank around the gas cap | Replace the gas cap |
10. Runs Rough
When your SCAG begins to run rough and sluggishly, you need to look for items that restrict the amount of air, fuel, or spark the engine receives so it can continue to run well.
In addition to this, look for things that may cause the engine to have to work harder than normal. This can be from operating the mower too fast, having the mower deck plugged with grass clippings, and running dull mower blades.
For More Information Check Out:
Reasons a SCAG Mower Runs Rough & Sputters (Coming Soon)
| Potential Cause | Solution |
|---|---|
| Old fuel | Drain old fuel. Refill with a gas and fuel stabilizer mixture. |
| Clogged fuel line | Remove a clogged fuel line and remove the clog using carburetor cleaner and compressed air. Install a new fuel line when the clog can’t be removed. |
| Plugged fuel filter | Replace the fuel filter. |
| Dirty carburetor | Remove the carburetor to clean it. Rebuild or replace it if needed. |
| Bad gas cap | Replace a gas cap that no longer allows the fuel tank to vent. |
| Dirty spark plug | Clean a dirty plug using a wire brush. Install a new one if it is very dark in color, worn, or damaged. |
| Fast ground speed | Slow down the ground speed to match the mowing conditions. Slow down when mowing tall, thick, or wet grass so the engine isn’t under too much load. |
| Low engine speed | Place the throttle lever in its highest position when engaging the mower blades. |
| Plugged mower deck | Scrape the mower deck to keep it clean. |
| Dull mower blades | Sharpen the mower blades. |
11. Blades Won’t Engage
The mower blades won’t engage on a SCAG zero turn when the PTO switch is faulty, the battery is weak, a safety switch failed or the clutch is bad.
The blades won’t turn when the belt is worn or has fallen off the pulleys due to a stretched belt, bad pulley bearing, or worn tensioner parts.
For More Information Check Out:
SCAG Mower Blades Won’t Engage or Turn On (Coming Soon)
| Potential Cause | Solution |
|---|---|
| Worn mower deck belt | Replace a belt that is worn, cracked, or has a shiny glazed appearance. |
| Belt falls off the pulleys | Replace worn or damaged deck parts including a worn idler arm, worn spring or bad pulleys. Replace a stretch mower deck belt. |
| Bad PTO switch | Replace the PTO switch. |
| Bad clutch | Replace the clutch. On a manual engagement clutch, replace a worn clutch cable, lever, springs, and linkages. |
| Weak battery | Test the battery and place it on a charger if the reading is less than 12.7 volts for a 12-volt battery. Replace the battery when it won’t hold a charge. |
| Bad Safety switch | Replace the safety switch |
| Blown fuse | Replace the fuse with a fuse with the same amperage. |