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John Deere D125 Troubleshooting
The
John Deere D125 lawn tractor was manufactured from 2014 to 2017. The JD D125
powerline components: Briggs and Stratton 40R877 4-cycle V-twin cylinder OHV
air-cooled gasoline engine and Tuff Torq T40 belt-driven hydrostatic
transmission with infinite forward and reverse gears.
A 40.1 cubic inches (655 cc) engine has a cylinder bore of 2.97" (75
mm), piston stroke of 2.89" (73 mm), and rated power of 20 hp (14.9 kW).
Max. forward speed - 5.5 mph (8.8 km/h), maximum reverse speed - 3.2 mph
(5.1 km/h).
The John Deere D125 is equipped with a manual steering system, disc
brakes, 15x6.00-6 front tires, and 20x8.00-8 rear tires. The wheel base
is 49" (1240 mm). The lawn tractor is compatible with the following
attachments: 42" mid-mount 2-blade mower deck with cutting height of
1-4" (25-102 mm), 43.25" front-mount 2-stage snowblower with clearing
height of 18" (450 mm), and 46" front blade with mechanical lift system.
| Engine Troubleshooting |
| Engine will not start or starts up hard |
| No gasoline in tank - Fill fuel up |
| Wrong grade of gasoline - Use quality gasoline |
| Water or air in fuel system - Remove air or water from system |
| Defective spark plug wire connection - Inspect the spark plug wire connection, replace or repair |
| Spark plug is defective - Change spark plug |
| Fuel filter is plugged - Change fuel filter |
| Brake pedal not pushed down - Push the brake pedal down |
| Carburetor components worn out - Repair or replace parts |
| Low cylinder compression - Check cylinder block and replace worn parts |
| Improperly adjusted or worn throttle cable - Adjust properly or change the cable |
| Clogged cooling fins - Need to wash or clean |
| Ignition system failure - Check ignition system and replace faulty parts |
| Stuck or faulty choke cable - Clean or replace the cable |
| Air filter element is plugged - Replace or clean air filter |
| Dirty or defective fuel pump - Clean or install new fuel pump |
| Engine starts and stalls immediately |
| Faulty spark plug - Replace spark plug |
| Clogged or defective carburetor - Service or change carburetor |
| Ignition coil is not working - Change ignition coil as required |
| Loose or broken valve springs - Install new valve springs |
| Valves are stuck - Valves must be cleaned |
| Not enough engine oil - Fill the crankcase with engine oil |
| Engine is overloaded - Load reducing is recommended |
| Cooling fins are plugged - Clean and wash as required |
| Carburetor mixture is too lean - Use proper settings |
| Ignition timing is wrong - Set the ignition timing correctly |
| Valve setting is improper - Set the valves correctly |
| Engine knocking sound or abnormal noise |
| Stale or low octane fuel - Use proper gasoline |
| Engine overloaded - Reduce engine load |
| Engine oil level low - Add oil to the engine crankcase |
| Low idle speed set incorrectly - Test and adjust |
| Fuel pump is faulty or clogged - Clean or install new fuel pump |
| Main bearings or crankshaft wear - Change or repair worn components |
| Excessive valve clearance - Need to adjust valve clearance |
| Piston rings or cylinder bore are damaged - Replace defective components |
| Carburetor is incorrectly adjusted or clogged - Clean or correctly adjust carburetor |
| Dirty air filter element - Change or service air filter |
| Clogged or defective fuel pump - Test fuel pump and change if necessary |
| Ignition failure - Check ignition and replace faulty components |
| Cylinder head gasket is blown - Replace cylinder head gasket |
| Valves are burned or stuck - Change or service valves |
| Push rod is worn or defective - Replace push rod |
| Cylinder block parts are damaged - Defective parts need to be replaced |
| Engine using too much gasoline |
| Insufficient choke opening - Inspect choke cable and adjust as required |
| Improper carburetor main jet adjustment - Adjust it properly |
| Spark plug is loose or defective - Spark plug need to be tightened or replaced |
| Valves are stuck, worn, or burned - Replace or clean valves |
| Sleeve, piston, or rings are damaged - Replace defective components |
| Valve clearance is not correct - Need to adjust valve clearance |
| Excessive oil consumption |
| Defective seals or gaskets - Install new components |
| Damaged valve stems or valve guides - Change the valves |
| Piston rings are seized or worn - Piston rings replacement required |
| Scuffed piston or cylinder liner - Inspect piston and liner, replace as required |
| Breather hose or pipe is blocked - Service or replace |
| Hydrostatic Transmission Troubleshooting |
| HST transmission noise |
| Speed control linkage is worn or unadjusted - Adjust or replace linkage |
| Transmission overload - Reduce loading |
| Transmission fluid is dirty or fluid level is too low - Pour fresh fluid or add transmission fluid to proper level |
| Worn or defective transmission components - After disassembly and inspection, replace defective components |
| Shift linkage is rusty or worn - Lubricate or replace the linkage |
| Hydrostatic pump is blocked or defective - Change or repair pump |
| Unadjusted or damaged transmission shift control parts - Adjust correctly or replace |
| Transmission fluid insufficient - Need to add transmission fluid |
| Drive pulley is worn or faulty - Replace pulley |
| Shifter linkage is faulty or not adjusted - Adjust properly or replace linkage |
| Worn or out of adjustment speed control linkage - Adjust or repair linkage |
| Damaged transmission seals or gaskets - Seals and gaskets need to be replaced |
| Final drive shaft leaks - Replace shaft seals |
| Cracked transmission housing - Install a new transmission housing |
| Mower Deck Troubleshooting |
| Mower vibrates too much |
| Mower deck drive pulley is worn or dirty - Clean or change pulley |
| Loose or damaged drive belt - Adjust belt tension or replace belt |
| Warped or not balanced mower blades - Balance or change as needed |
| Blade mounting bolts are loose - Bolts need to be tightened |
| Constant clogging of discharge chute |
| Ground speed is too fast - Operate at slower speed |
| Tall grass - Adjust mower to lower cutting height |
| Reduced engine speeds - Open choke fully |
| Mower cuts too low - Change cutting height adjustment |
| Drive belt installation is not correct - Install drive belt correctly |
| Lawn mower leaving uncut grass |
| Discharge area is clogged - Need to clean the mower deck |
| Not sharp blades - Need a blade sharpening |
| Worn or damaged blades - Replace the blades |
| High mowing speed - Operate at slower speed |
| Cutting level is too low - Must be set to high cutting height |
| Bagger is full - Clean bagger |
| Blades are scalping the grass |
| Lawn is not level or bumpy - Lawn leveling required |
| Low cutting height - Raise the cutting height |
| Ground speed is too fast - Use a slower speed |
| Improperly leveled mower deck - Level the deck correctly |
| Blades are worn or bent - Replace the blades |
| Tires are not properly inflated - Correct tire pressure |
| Tire pressure is too low - Inflate tires as required |
| Improperly leveled mower deck - Adjust the level of mower deck correctly |
| Blades are excessively dull - Need a blade sharpening |
| Blades are defective or worn - Blades must be changed |
| Cutting deck is clogged - Clean mower deck as required |
| Damaged mower deck shell - Repair or change the deck |
| Loose or faulty mower spindle - Change or repair the spindle |
| Electrical Troubleshooting |
| Battery does not charge |
| Loose or corroded electrical wiring connections - Tighten or clean electrical wiring connections |
| Electrical terminal connectors are faulty - Terminal connectors should be replaced |
| Battery failing - Replace the battery |
| Low battery power - Battery is drained, recharge it |
| Battery won’t hold charge - Service battery or change it |
| Disconnected wiring or bad battery terminals - Connect wiring properly or install new terminals |
| Battery is low or faulty - Recharge or replace battery |
| Wiring is incorrectly connected or disconnected - Inspect wiring and connect correctly |
| Battery capacity is low - Battery is drained, recharge it |
| Incorrectly gapped or worn spark plug - Clean, gap or replace spark plug |
| Starter motor or solenoid is defective - Starter/solenoid needs to be replaced |
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| Lawn and Garden Tractors Technical Specs |
