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Common SCAG Lawn Mower Problems & Solutions

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.

The most common SCAG lawn mower problems are:

  • SCAG mower doesn’t start
  • SCAG mower starts then dies
  • SCAG mower is smoking
  • SCAG mower has a weak hydrostatic transmission
  • SCAG mower won’t drive straight or steer correctly
  • SCAG mower won’t move
  • SCAG mower is shaking or vibrating
  • SCAG mower is cutting uneven
  • SCAG mower is leaking gas

To keep your mower running at it’s 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 prior to diagnosing, repairing or operating. Consult a professional if you don’t have the skills, 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.

SCAG Lawn Mower 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 a 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, bad switch or faulty charging system.

Detailed information can be found at:
15 Reasons Your SCAG Lawn Mower Won’t Start

CauseReason for ProblemSolution
No gas in the fuel tankFuel tank is emptyFill with fresh fuel
Bad or old fuelFuel breaks down overtime making your fuel less efficient and prone to clogging the fuel systemDrain the fuel tank and fill 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 capThe 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 flowReplace a clogged fuel tank vent.
Bad spark plugExcessively dirty or broken spark plug; bad connection; not gapped correctlyReplace with a new spark plug, secure connections and ensure it is gapped to manufacturer specifications
Plugged air filterDirt and grass can plug the air filter preventing air flowRemove the filter and clean it. Replace the filter if it is in bad condition.
Plugged fuel filterA dirty fuel filter will restrict fuel flowReplace the fuel filter
Bad fuel pumpA failed or leaking fuel pump will no longer create pressure needed to pump fuelReplace the fuel pump
Blocked fuel linesBad fuel deposits and dirt can build up and clog the fuel lines preventing the engine from getting the required fuelUse a carb cleaner and compressed air to clear the clog out of the fuel line. Replace line if necessary.
Dirty carburetorThe carburetor can become dirty and clogged due to bad fuel and ethanol deposits preventing fuel flowClean the components making up the carburetor. Replace if needed.
Bad battery or loose & dirty terminalsA dead battery, loose cables or corroded terminals can cause starting problemsCharge your battery and replace if it won’t hold a charge. Make sure your cables are tight and clean the corrosion from terminals.
Bad safety switchSafety switches is a safety measure that exist 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 coilYour mower will not start when either the ignition switch or coil is badTest and replace a bad switch
Bad charging systemA charging system that can’t keep your mower charged and is constantly draining the battery must be repaired to prevent starting problems.Take your lawn mower to your local SCAG dealer for assistance identifying which part of the charging system has failed.
Reasons Your SCAG Mower Won’t Start

SCAG Lawn Mower Starts Then Dies

You may be able to get your SCAG mower to start, but after running 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!

CauseReason for ProblemSolution
Bad fuelFuel breaks down overtime making your fuel less efficient and prone to clogging the fuel system and engine damageDrain the fuel tank and fill with fresh fuel. Use a fuel additive like Sea Foam to stabilize the fuel and assist with cleaning the fuel system
Plugged air filterDirt and grass can plug the air filter preventing air flowRemove the filter and clean it. Replace the filter if it is in bad condition.
Dirty or broken cooling finsCooling fins get packed with dirt, oil and grass not allowing air to effectively cool the engine blockReplace broken fins and clean the cooling fins.
Clogged fuel lines or filterBad fuel deposits and dirt can build up and clog the fuel lines preventing the engine from getting the required fuelUse a carb cleaner and compressed air to clear the clog out of the fuel line. Replace a plugged fuel filter.
Dirty carburetorThe carburetor can become dirty and clogged due to bad fuel and ethanol deposits preventing fuel flowClean all components making up the carburetor. Replace if needed.
Too Much or Too Little Engine OilToo much engine oil increases pressure in the crankcase causing it to overheat and die. Too little oil doesn’t provide the lubrication parts need 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 PlugDirty or damaged spark plug causes 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 CoilA windings on the coil can separate and short out on a bad ignition coilCheck for a break in the continuity using an ohm meter and replace is found bad
Choke is in the Wrong PositionA 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.
Battery is Not ChargingA battery that doesn’t hold a charge or a bad charging system that can’t keep the battery charged will cause your SCAG mower to die after running.Test your battery and charging system. Replace any electrical components found to be bad. Read more about testing your battery and charging system here.
Bad Fuel Tank VentGas 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 DeckClogged mower deck causes a strain on the engine causing it to work hard and possibly shut downPeriodically scrape your mower deck to keep it clean
Reasons Why Your SCAG Mower Dies While Mowing

SCAG Lawn 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 test to accurately diagnose and perform necessary repairs.

Detailed information can be found at:
Why Your SCAG Lawn Mower is Smoking
– Article Coming Soon

CauseReason for ProblemSolution
Plugged air filterDirt and grass can plug the air filter preventing air flowRemove the filter and clean it. Replace the filter if it is in bad condition.
Too much oil in the crankcaseExcessive oil can cause pressure to build in the engine allowing oil to get into the cylinder through the valve trainDrain a little engine oil until it is at the manufacturers recommended oil level.
Engine oil level is too lowLack 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 have this fix your engine problem.
Internal problems including the piston ring, valve train or engine gasketInternal 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
Reasons Why Your SCAG Mower is Smoking

SCAG Lawn Mower Has a 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.

CauseReason for ProblemSolution
Bad drive beltA bad drive belt can cause your pump not to work efficientlyReplace a frayed, cracked or worn belt
Bad tensioner pulleyWhen a tensioner pulley fails, it fails to keep tension on the drive beltReplace the pulley and grease the tensioner arm
Low or old hydraulic oilLow or old hydraulic oil can fail to lubricate the hydraulic system causing your hydraulic system to seem weakChange your hydraulic oil at regularly intervals as recommended by SCAG.
Check your hydraulic oil periodically to ensure your hydraulic fluid is full.
SCAG Mower’s Hydrostatic Transmission Seems Weak

SCAG Lawn Mower 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.

CauseReason for ProblemSolution
Incorrect tire pressureUnequal tire pressure can cause your mower to pull to one side.Check tire pressures and keep them filled to the manufacturers spec. Tires on each side of your mower requires equal pressures.
Bad dampers on zero turnBad dampers will cause your mower to jerk to one side when moving forwardReplace with a new damper
Tracking adjustment needed on zero turnWhen one tire is moving faster than the other, your mower can pull to one sideAdjust speed adjustment bolt to change the rotation speed of the tire. Refer to your owner’s manual.
Reasons Why Your SCAG Mower Won’t Drive Straight or Steer Correctly

SCAG Lawn 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, broke 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

CauseReason for ProblemSolution
Drive release lever in the wrong positionThe drive release arms allows hydrostatic mowers to roll freelyThe drive release arms must be in the operating position.
Drive pump belt is wornThe 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 pulleyThe bearing in the tensioner pulley can failReplace the tensioner pulley
Missing idler arm springIf the idler arm spring breaks or goes missing, it can no longer place tension on the drive beltReplace the broken or missing spring
Low or old hydraulic oilLow or old hydraulic oil can fail to lubricate the hydraulic system causing your hydraulic system to seem weakChange your hydraulic oil at regularly intervals as recommended by SCAG.
Check your hydraulic oil periodically to ensure your hydraulic fluid is full.
Hot hydraulic fluidHot hydraulic fluid can be a sign of damage to your hydrostatic transmission systemLet your hydraulic oil cool. If you find your mower runs fine when it is cold, but does becomes weak when the hydraulic system gets hot, have your mower checked at your local SCAG dealership.
Air in the hydraulic systemAir must be bled from the hydraulic system after changing your hydraulic fluid or the mower will not be able to move at normal speedsFollow SCAG’s procedures for changing hydraulic fluid and bleeding air from the system as outlined in your owner’s manual.
Reasons Why Your SCAG Will Not Move or Go Forward

SCAG Lawn Mower is Vibrating and Shaking

Vibration in a mower can be caused by something as small as 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

CauseReason for ProblemSolution
Loose or missing engine mounting boltsEngine bolts are used to reduce vibration of the mower when the engine is runningSecure engine bolts and replace any missing bolts
Clutch is badWhen there is bearing failure and it falls out of the clutch it can cause vibration. Replace the clutch
Unbalanced or damaged mower bladesDamaged and unbalanced blades can send a vibration through your mower. Blades must be balanced before installingReplace any damaged blades and make sure they are balanced.
Material wrapped around the blade spindleForeign materials like string or long weeds can get wrapped around your blade shaft causing vibrationRemove all debris and items wrapped around the blade shaft. Check for spindle damage.
Bad spindle housing bearingsVibration can be caused by a bad bearing in the spindle housing.Replace bearing in the spindle housing or replace the whole spindle housing assembly
Worn pulleys or deck beltCheck deck belt and pulleys for wearing of the belt and bearing failure in the pulleysReplace any damaged or worn belts and pulleys
Debris lodged in mowerThe 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.
Reasons Your SCAG Lawn Mower is Vibrating

SCAG Lawn Mower Has a 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 to 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 bladeUneven tire pressuresEngine speed is too low
Bent mower bladeUnleveled mower deckGround speed is too fast
Blade installed wrongBent blade spindle or spindle bearingDamaged deck shell
Clogged Mower DeckWorn deck pulleys or beltOperator error
Reasons Your SCAG Lawn Mower is Cutting Uneven

SCAG Lawn Mower is Leaking Gas

Often times, 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

CauseReason for ProblemSolution
Dirty of Failed CarburetorThe carburetor can collect a buildup of substances remaining from old gas that can cause blockages or parts failures resulting in a leakClean the carburetor and replace any damaged parts
Old Fuel FilterFilter can become soft and degrade from old fuelReplace fuel filter
Bad Fuel PumpPump can wear and deteriorate over time and may begin leaking at the seamsReplace the fuel pump
Bad Fuel Tank SeamsA poly tank can leak at the seams of the tankReplace the fuel tank.
Bad Fuel Shut-Off ValveShut-off valves are prone to leaking with timeReplace the shut-off valve
Cracked or Punctures Fuel LinesRubber fuel lines become dry and cracked causing gas to leak. They can also be punctures by a foreign object or the clamps used on the lines.Replace the fuel lines
Bad Seal in the Gas CapThe gas cap seal can fail and no longer seal allowing gas to splash out of the fuel tank around the gas capReplace the gas cap
Places Your SCAG Mower May Be Leaking Gas