Common Scag Zero-Turn Mower Problems
Although Scag zero-turn mowers are durable, efficient, built to last, and comfortable to use.
It is possible for your Scag zero-turn mower to develop a fault at any time and this can be frustrating, especially when you have an overgrown lawn that needs trimming.
In this article, we share well-detailed Scag zero-turn mower problems and practical fixes to ensure smooth mowing operation.
But before we jump right into the possible solutions…
Some of the most common Scag zero-turn mower problems are:
- Scag zero-turn mower fails to start
- Scag zero-turn mower won’t move
- Vibration problems
- Scag zero-turn mower loses power and dies
- Bad or uneven cut
Scag Zero-Turn Mower Problems: Causes and Solutions
1. Scag Mower Fails to Start
If your Scag mower won’t start, it might be because of air or gas restrictions not allowing the engine to get the required air and gas to run.
This can occur as a result of a defective spark plug, bad solenoid, a failed electrical component or a dead battery.
| Cause | Reason for Problem | Solution |
| Old or Bad Gas | Gas breaks down over time and makes it less efficient, clogging the gas system | Use a fuel siphon and take out the gas from the gas tank. Stabilize the gas by using a fuel additive. |
| No gas in the tank | Gas tank is empty | Fill with fresh gas |
| Defective spark plug | Bad connection; Broken or dirty spark plug; not gapped correctly | Secure connection; Replace the faulty spark plug and make sure that it is gapped correctly |
| Clogged or faulty fuel | The vent may get clogged andcreate a vacuum in the tank, restricting the flow of fuel | Clear the blocked vent with a thin piece of wire or replace the cap if necessary. |
| Faulty charging system | If the charging system isn’t able to hold the mower charged and drains the battery, it is advisable to repair it | Seek the help of an expert to help you identify the problem and fix it. |
| Broken recoil | A damaged or broken recoil may prevent it from starting the engine | Inspect recoil to know if you can re-string it. Broken parts like the pulley should be replaced or you replace the entire recoil assembly if necessary. |
| Clogged air filter | A blocked and dirty fuel filter will restrict the flow of fuel. | Replace fuel filter |
| Dirty carburetor | The carburetor can become dirty due to bad gas and ethanol deposits that preventthe flow of fuel | Clean the components of the carburetor or replace if needed |
| Faulty ignition switch or coil | A bad coil or ignition or coil will make the mower not to start | Test and replace the defective ignition switch |
| Bad safety switch | If the switch fails, it may prevent the mower from starting | Test and replace defective safety switch |
| Faulty battery or dirty and loose terminals | Loose cables, corroded terminals or a dead battery may make the mower not start | Ensure that the cables are tight and clean corroded terminals. Charge the battery or replace the battery |
2. Mower Loses Power and Dies
Your Scag mower can lose power when the air or gas systems are compromised, affecting the mower’s operation.
This problem may be related to clogged fuel lines, a dirty carburetor, a bad air filter, and bad gas.
| Cause | Reason for Problem | Solution |
| Bad Gas | Gas degrades over time making the fuel less efficient and liable to engine damage and clogging the fuel system | Drain the gas tank and fill it with fresh gas. Use fuel additives to stabilize fuel |
| Broken or dirty cooling fins | The cooling fins may be filled with oil, grass, and dirt which will not allow the air to properly cool the engine block | Clean the cooling fins orreplace them with new ones |
| Blocked air filter | Grass and dirt can block the air filter to prevent air flow | Remove the filter andclean it. Replace it if it is in a bad condition |
| Clogged fuel lines | Dirt and gas deposits can accumulate and block the fuel lines, causing the engine not to get the required gas | Clear the clog out the fuel line by using compressed air and carb cleaner |
| Dirty carburetor | This may be caused by bad gas and ethanol deposits which prevents the flow of fuel | Clean all the parts that make up the carburetor or replace if needed |
3. Scag Zero-Turn Mower Smokes
Your Scag zero-turn mower can smoke when the oil gets into the cylinder and starts to burn off.
Some parts begin to burn as a result of increased friction from low oil capacity. This can also result in internal engine failure.
| Cause | Reason for Problem | Solution |
| Internal problems including engine gasket, piston ring or valve train | Internal engine problems may cause serious effects if they are not quickly detected and fixed | Take the mower to a local small engine shop for fixing |
| Low engine oil level | Lack of oil may increase friction in the engine, causing extreme heat in the engine | Take the mower to a small engine repair shop to check for engine damage |
| Blocked air filter | Grass and dirt can block the air filter which prevents air flow | Take off the air filter and clean it or replace it if it is bad |
| Excess oil in the crankcase | Too much oil can cause pressure to build in the engine, enabling oil to gain access into the cylinder through the valve train | Drain a little engine oil until it meets manufacturer’s recommended oil level |
4. Weak Hydrostatic Transmission
A weak hydrostatic transmission may occur due to a worn or broken drive belt or tensioner pulley.
| Cause | Reason for Problem | Solution |
| Faulty tensioner pulley | If the tensioner pulley fails, it fails to keep the tension on the drive belt | Replace the pulley and grease the tensioner arm |
| Old or low hydraulic oil | Old or low hydraulic oil may not lubricate the hydraulic system, causing the hydraulic system to be weak | Check the hydraulic oil periodically to be sure thatThe hydraulic fluid is full. Change the hydraulic oil regularly in line with the recommendations of Scag |
| Bad drive belt | A bad drive belt may prevent the pump from functioning well | Replace worn, cracked, or frayed belt |
5. Mower Won’t Steer Correctly Or Drive Straight
Your zero-turn mower may experience these problems as a result of bad dampers, worn steering parts, and incorrect tire pressures.
The tracking may be off on your Scag zero-turn mower, causing it to veer off to the left or right.
| Cause | Reason for Problem | Solution |
| Loose or worn steering parts in riding lawn mower | Worn washers, gears and bushings can prevent the mowing machine from steering in a way or the other | Check and replace failedparts on the steering system |
| Bad dampers | Bad dampers may cause it to jerk to one side when moving in forward position | Replace bad damper with a new one |
| Incorrect tire pressure | Incorrect tire pressure may make the zero-turn mower to pull to one side | Inspect tire pressure and keep them filled as specified by the manufacturer. The tires must have equal pressures. |
| Tracking adjustment neededon a Scag zero-turn mower | The mower can pull to one side if one tire is moving faster than the other. | To change the rotation speed of the tire, adjust the speed adjustment bolt. Check the owner’s manual |
6. Scag Zero-Turn Mower Won’t Move
This is one of the common problems of a Scag zero-turn mower.
This can occur as a result of a missing idler spring, bad drive belt, or worn tensioner pulley.
If the drive release lever and transmission bypass rod aren’t in the right position, it may cause the mower not to move.
| Cause | Reason for Problem | Solution |
| Worn drive pump belt | It won’t move forward if the drive belt is worn or falls off | Replace the cracked or worn belt. Ensure that the belt is secure around the pulleys |
| Bypass rod or drive release lever is in the wrong position | A wrongly positioned bypass rod or drive release will not allow mower to move freely | The bypass rod must be the disengaged while the drive release lever should be in the operating position |
| Missing idler arm spring | A broken or missing idler arm spring will no longer place tension on the drive belt | Replace missing or broken spring |
| Faulty tensioner pulley | The bearing in the tensioner pulley can fail | Replace the tensioner pulley |
| Old or low hydraulic oil | Old or low hydraulic can fail to lubricate the system | Check the hydraulic oil at periodic intervals to be sure that the hydraulic fluid is full.Change the hydraulic oil regularly in line with Scag’s recommendations |
| Air in the hydraulic system | The Scag zero-turn mower won’t be able to move at normal speeds if the air isn’t bled from the hydraulic system after changing the hydraulic fluid | Follow the recommendations of Scag to change the hydraulic fluid. Check the owner’s manual to bleed air from the system |
| Hot hydraulic fluid | A hot hydraulic fluid can damage the hydrostatic transmission system. | Allow the hydraulic oil to be cool. It is advisable to check the mower at the local Scag dealership if the hydraulic system gets weak when hot |
7. Vibration Problems
The Scag zero-turn mower may vibrate because of unbalanced or damaged blades, or failing components including bearings in the clutch, spindle housings, and pulleys.
Other possible causes include loose components and hardware on the mower, and debris lodged under the mower’s pulleys and other places where small items can get stuck in the mower.
| Cause | Reason for Problem | Solution |
| Failing clutch | When there is bearing failure and it falls out of the clutch, it may cause vibration problems | Replace the clutch |
| Damaged or unbalanced mower blades | Damaged or unbalanced blades can cause the mower to vibrate | Replace damaged blades and ensure that they are balanced |
| Debris lodged in Scag mower | Acorns, woodchips, stones and other debris can get lodged in the mower. This causes it to shake | Inspect the mower deck and other places where small items can get stuck in the mower. Remove all foreign materials |
| Bad deck belt or pulleys | Inspect the pulleys and belt for bearing failure and wear | Replace any worn or damaged pulleys and belts |
| Bad bearings in the spindle housing Foreign material around mower blade shaft | Bad bearings in the spindle housing can cause vibration Foreign materials like long weeds, string or wire can get wrapped around the blade shaft or spindle shaft to cause vibration | You can replace only the bearing but it’s best to replace the entire spindle housing assemblyRemove foreign materials that are wrapped around the blade shaft. |
8. Hydro Belt Problems
Some users complained about the recurrent breakage of the hydro belt. The sizes of the pumps are increased on the TC2 but the wheel motors are not raised to that ratio.
In this case, there is an excessive load on the belt, causing it to break. This problem is common with Scag Tiger Cat 2 zero-turn mowers.
| Cause | Reason for Problem | Solution |
| Broken hydro belt | Excess load on the belt causes recurrent breakage of the hydro belt | Call a technician to fix it |
9. Scalping
Scalping is when the mower deck comes close to or hits the ground. This problem may occur as a result of low tire pressure, mowing on wet grass and ground speed too fast.
| Cause | Reason for Problem | Solution |
| Low tire pressures | When the tire is lower in pressure, the mower can scalp the lawn | Check and adjust pressures |
| Ground speed too fast | Mowing too fast on grass can cause lawn scalping | Slow speed to adjust for conditions |
| Wet grass | Mowing on wet grass can make the grass to clump together which may result to scalping | Cut grass after it has dried out |
10. Scag Zero-Turn Mower Won’t Crank
The Scag zero-turn mower may face issues with cranking and might affect the operation and functionality of the mower.
This problem may occur as a result of a dead battery. It is important to check the battery’s condition if it is charged or not.
| Cause | Reason for Problem | Solution |
| Dead battery | If the battery isn’t charged, the mower may face issues with power | Charge the battery.Replace cell or battery if it is in a bad condition |
11. Uneven or Bad Cut
Your Scag zero-turn mower may cut unevenly because of defective components such as a damaged or worn blade, unleveled mower deck, uneven tire pressures, clogged mower deck and slow engine speed.
| Cause | Reason for Problem | Solution |
| Mower deck is clogged with dirt | Grass buildup beneath the deck can cause bad cut | You may use silicone spray but it may not solve the problem.Mow the lawn regularly to prevent grass from clumping. It’s best not to avoid mowing on wet grass. |
| Incorrect tire pressures | When one tire is lower in pressure than the other, the deck can sit unevenly andgive you an uneven cut | Ensure that the tires have thecorrect tire pressure |
| Bent blade | Bent blades can affect the cut of the lawn and leave it with an uneven cut | Replace bent blade with a new one |
| Worn or dull blade | If the mower blades are excessively worn, it may leave strips of grass behind | Replace worn mower blades |
| Blades are installed wrongly | Placing the mower blades upside down can cause them to hit the ground which candamage the grass and mower | Ensure that the blades are sharpened before installation |
| Bent blade spindle | Bad deck bearings can make your mower have a bad cut | Check for bad bearing in the spindle housing or a quill assembly. |
| Bad deck belt or pulleys | A cracked belt or bad belt from a pulley might cause a bad cut | Replace the belt and pulley |
| Engine speed is too low or ground speed is too fast | Mowing too fast on tall or thick grass can make you get a bad cut because some of the grass will be pushed over | If you are mowing on a weedy, you may not be worried by the quality of the cut and can mow a bit faster but move a bit slower mowing your front yard. You also need to slow down the ground speed of your mower while mowing tall or thick grass. |
| Deck shell is damaged | The deck shell can get damaged by running the mower into rocks, trees, and other hard surfaces, causing a bad cut | It is advisable to seek the help of an expert to fix it |
12. Engine Overheats
The engine of your Scag zero-turn mower can overheat due to low engine oil level or restricted airflow, affecting the operation of the mower.
| Cause | Reason for Problem | Solution |
| Low engine oil level | The engine may overheat because the oil level is low. | Fill the crankcase with the right amount and weight of oil. |
| Restricted airflow | There is a restriction in the air flow | Clean debris and grass clippings from and cooling fins and blower housing. |
13. Leaking Gas
This issue may occur if the carburetor bowl gasket is damaged. This will affect the operation and functionality of the Scag zero-turn mower.
| Cause | Reason for Problem | Solution |
| Damaged or missing Carburetor bowl gasket | A damaged carburetor bowl gasket can cause gas to leak | Replace the carburetor bowl gasket |
14. Scag Zero-Turn Mower is Difficult to Start
Some Scag owners have complained about the mower taking much time before starting. This may be due to a clogged carburetor.
When gas is left for a long time, it becomes sticky and clogs your carburetor.
| Cause | Reason for Problem | Solution |
| Clogged carburetor | Old gas may become sticky and can clog the carburetor | Replace the clogged carburetor |
Scag Zero-Turn Mower Not Getting Gas
If your Scag Turf Tiger II or any other Scag zero-turn lawn mower does not get gas, the problem may be due to:
- Bad Fuel
- Plugged fuel filter
- Clogged fuel lines
- Bad fuel pump
- Dirty Carburetor
Troubleshooting Tips
- Use a siphon pump to drain the gas tank and refill it with fresh fuel. Ensure that you add a fuel additive to the fresh gas to clean and stabilize the fuel system.
- Replace the clogged fuel filter with a new one.
- Replace the fuel line with a new one.
- Replace a damaged fuel pump with a new one.
- To clean the dirty carburetor, spray the carburetor cleaner into the air intake.
Scag Zero-Turn Mower Blades Won’t Engage
If your Scag zero turn mower blades won’t engage, it may be as a result of the following reasons:
- Corroded connections
- Faulty seat switch
- Defective PTO clutch
- Faulty PTO switch
- Damaged or worn-out belt
Troubleshooting Tips
- Check all the wires that go to the PTO. Unplug and clean all connections
- Replace faulty safety switch
- Replace PTO clutch
- Replace the bad PTO switch with a new one.
- Inspect the belt and replace it if it is damaged or worn out
How Do You Clean the Carburetor on a Scag Zero-Turn Mower?
Here are the steps for cleaning the carburetor of your Scag zero-turn mower:
Spray Carburetor Cleaner Into The Air Intake
The first step to take is to remove the air filter from the air filter housing. Spray the carburetor cleaner into the air intake.
Check if the engine will start and continue to operate. If the engine does not start but shuts down, you need to disassemble the carburetor for cleaning.
Take Pictures for Reassembly
It is advisable to take photos while you disassemble it. Some components might come apart and you may find it difficult to remember their position when you have disassembled them.
Taking photos of this process will enable you to reassemble them with ease
Turn off the Fuel Supply
To shut off the fuel supply, you need to use pliers or a fuel hose pinch to crimp the fuel line. You can also turn off the fuel shut-off valve. After that, take off the fuel line from the carburetor.
Take off Choke Cable and Throttle Cable
Remove the choke cable and throttle if your mower has one.
Remove the Filter Housing
Take off the nuts and screws that attach the carburetor to the filter housing.
Take Off the Springs
Slowly remove the springs but you need to be careful not to stretch them out.
To remove the springs, you have to twist the carburetor a bit. Ensure that you do not tear the gasket that is found between the carburetor and engine block.
Remove the Float Bowl
You can locate the float blow at the base of the carburetor. The float bowl is where the gas is stored in the carburetor. This component is held by a screw.
Before removing the bowl, ensure that you clean around the outer part of the carburetor bowl to eliminate dirt. After that, remove the screw from the bowl’s base.
Make sure that you get a rag to catch the remaining gasoline in the bowl.
Do not damage the o-ring while trying to remove the bowl. In addition, make sure that you do not get the carburetor cleaner on the o-ring.
Inspect the Stem for Plugged Holes
A clogged stem will prevent the carburetor from bringing fuel to the jet. Locate the holes with a flashlight and disconnect them with a thick wire.
Inspect the Carburetor for White Crusty Build-up
Use a carburetor cleaner to remove white crusty material. It is quite impossible to get all the white deposits out of the carburetor.
Reassemble the Carburetor
After cleaning, you can now reassemble the carburetor. Check the photos that you took earlier to be sure that the parts are in the proper position.
Reattach parts to the carburetor including choke and throttle cable( if it uses one), fuel line, filter housing, and springs.
Fill the Gas Tank with Fresh Gas Mixed With A Fuel Additive
Fill the gas tank with fresh gas and mix it with a fuel additive. Allow the gas to fill the carburetor’s bowl and start the engine.
Note: You may need to replace the carburetor if it is in a bad condition.
Tools Required For Cleaning Scag Carburetor
Conclusion
If you notice that your Scag zero-turn mower is giving you issues, the first step to take is to figure out the causes. Some of the problems include vibration problems, weak hydrostatic transmission, and starting issues.
Follow the recommended fixes to get your Scag zero-turn mower working again. If your mower does not work properly after trying these troubleshooting tips, it might be best to seek a technician’s help.
Top Recommended Handy Tools for Troubleshooting & Servicing Your Lawn Mower
| Multimeter – This is useful for checking voltage, continuity & current to identify electrical problems in your mower | Filter Wrench – For loosening your mower’s filter. |
| Carburetor Cleaner – Choke and Throttle Body Cleaner for cleaning clogs & buildup in the fuel system. | Blade Balancer–Balances Blades After Sharpening. |
| Fuel Stabilizer – This stabilizes & cleans your fuel to reduce fuel system buildup | Battery Inflator – This helps to ensure your mower tires stay inflated to prevent steering or uneven cutting issues. |
| Socket & Allen Wrench Set – These tools are needed to service & troubleshoot your mower problems | Tachometer– Evaluates your mower’s engine performance and provides accurate data about the status of the engine |
| 12-Volt Battery Charger – This is useful for charging your mower battery. | Lawn Mower Blade Sharpener– Adjustable Lawn Mower Blade Sharpener for Right and Left Hand Blades. |