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John Deere D140 Troubleshooting

The John Deere D140 lawn tractor was manufactured from 2011 to 2017. The John Deere D140 tractor is powered by 40.03 cu.in (656 cc) Briggs and Stratton 407777 4-cycle V-twin cylinder OHV vertical-shaft air-cooled gasoline engine with a rated power of 21 hp (15.7 kW), or 44.2 cu.in (724 cc) Briggs and Stratton 44S677 4-cycle V-twin cylinder OHV vertical-shaft air-cooled gasoline engine with a rated power of 22 hp (16.4 kW).

The JD D140 is equipped with Tuff Torq T40 belt-driven hydrostatic transmission with infinite forward and reverse gears. The maximum forward speed - 5.5 mph (8.8 km/h), maximum reverse speed - 3.2 mph (5.1 km/h). The lawn tractor is equipped with a manual steering system, mechanical shoe brakes, 15x6.00-6 front tires, and 20x10.00-8 rear tires. The wheel base is 49" (1240 mm).

Compatible attachments for John Deere D140: a 48" mid-mount 3-blade mower deck with cutting height of 1.0-4.0" (25-102 mm), 13 cut positions, and manual lift with assist spring, 46" front blade with lift height of 6.5" (160 mm), and 44" front-mount dual-stage snowblower with clearing height of 18" (450 mm).

Engine Troubleshooting
Engine won't start or hard to start
Empty gas tank - Fill gasoline up
Low-quality gasoline - Use quality fuel
Air in the fuel system - Air bleeding
Disconnected or loose spark plug wire - Inspect the spark plug wire connection, replace or repair
Defective spark plug - Replace spark plug
Fuel filter is clogged - Fuel filter needs changing
Defective safety switch - Replace if required
Carburetor malfunction - Check and repair as required
Low compression - Check and replace worn parts
Throttle cable is adjusted improperly or worn - Change cable or adjust properly
Unstable engine running
Air intake grill is clogged - Need to clean or wash
Ignition system problems - Inspect ignition system and change failed components
Defective or stuck choke cable - Change or clean the cable
Air filter is dirty - Replace or clean air filter
Fuel pump is damaged or dirty - Test fuel pump and change if necessary
Engine starts but then stops
Defective spark plug - Install new spark plug
Carburetor is clogged or defective - Service or change carburetor
Ignition coil is faulty - Change ignition coil as required
Valve springs are bad or broken - Change valve springs
Valves sticking - Valves must be cleaned
Engine overheating
Not enough engine oil - Fill the crankcase with engine oil
Engine overloaded - Reduce engine load
Plugged cooling fins - Clean and wash as required
Carburetor mixture is too lean - Make the correct settings
Ignition timing is incorrect - Ignition timing needs to be set properly
Valve setting is improper - Adjust valves as required
Engine knocks or noises
Stale fuel - Use proper gasoline
Engine is under excessive load - Reduce load
Engine oil level is low - Check and refill engine oil
Low idle speed adjustment is incorrect - Correct the settings
Clogged or defective fuel pump - Service or change fuel pump
Crankshaft or main bearings failure - Need to install new components
Valve clearance is not correct - Need to adjust valve clearance
Damaged piston rings or cylinder bore - Change defective components
Loss of engine power
Dirty or incorrectly adjusted carburetor - Adjust the carburetor correctly or clean it
Air filter is blocked - Change or clean air filter
Fuel pump is damaged or dirty - Clean or change fuel pump
Ignition system malfunction - Inspect ignition system and change failed components
Worn cylinder head gasket - Replace cylinder head gasket
Valves are stuck or burned - Service or replace valves
Bent or worn push rod - Install a new push rod
Faulty cylinder block components - Replace defective parts as required
Engine uses too much fuel
Choke didn't open fully - Adjust or change choke cable
Incorrect carburetor main jet adjustment - Adjust it correctly
Loose or defective spark plug - Tighten or replace spark plug
Stuck, worn, or burned valves - Replace or service valves
Worn sleeve, rings, or piston - Replace faulty parts
Valve clearance is incorrect - Need to adjust valve clearance
Excessive oil consumption
Gaskets or seals may be damaged - Worn parts need to be replaced
Damaged valve stems or valve guides - Valves need to be changed
Damaged or seized piston rings - Install new piston rings
Worn cylinder liner or piston - Inspect piston and liner, fit new components as necessary
Breather hose or pipe is clogged - Service or replace

Hydrostatic Transmission Troubleshooting
Hydrostatic transmission makes noise
Worn or unadjusted speed control linkage - Repair or adjust linkage
Transmission overload - Reduce transmission load
Dirty transmission fluid or insufficient fluid level - Add fluid to correct level or fill the transmission with fresh fluid
Worn or defective transmission components - Replace or repair defective components
Difficult to shift
Stuck or damaged gshift linkage - Replace or repair the linkage
Hydrostatic pump is worn or stuck - Repair or replace pump
Transmission shift control components are defective or misadjusted - Change or adjust correctly
Low power
Low fluid level - Fill the transmission housing to proper fluid level
Defective or worn drive sheave - Replace sheave
Unadjusted or broken shift linkage - Adjust correctly or change linkage
Speed control pedal linkage is bent or not adjusted - Change or adjust linkage
Transmission leaking
Transmission gaskets or seals are damaged - Install new seals or gaskets
Final drive shaft leaks - Change shaft seals
Transmission case is cracked - Change broken case

Mower Deck Troubleshooting
Mower vibration is excessive
Dirty or worn mower drive sheave - Service or change sheave
Loose or worn drive belt - Belt needs to be adjusted or replaced
Unbalanced or warped mower blades - Balance or change as needed
Blade bolts are not tightened well - Tighten bolts as required
Constant clogging of discharge chute
High mowing speed - Use a slower speed
Long grass - Must be set to low cutting height
Reduced engine rpm - Adjust throttle to full opening
Cutting height is too low - Use correct cutting height
Drive belt installed improperly - Install drive belt correctly
Lawn mower leaving uncut grass
Clogged mower deck - Clean out the mower deck
Blades are not sharp - Sharpen the blades
Defective or worn blades - Blades need to be replaced
Ground speed is too fast - Need to slow down
Mower deck set to low cutting - Use correct cutting height
Full grass bag - Remove grass from bag
Blade scalped grass
Lawn is not level or bumpy - Lawn leveling required
Mower deck cutting height is set too low - Change cutting height adjustment
Fast ground speed - Use a slower speed
Deck level is not correct - Adjust the level of mower deck correctly
Blades are bent or worn - Replace the blades
Incorrect tire pressure - Inflate tires correctly
Uneven cut
Incorrect tire pressure - Correct tire pressure
Deck is not leveled correctly - Adjust the level of mower deck correctly
Excessive blade dullness - Need to sharpen the blades
Worn or bent blades - Change the blades
Mower deck is clogged - Need to clean the mower deck
Deck shell is damaged - Rebuild or replace mower deck
Mower spindle is faulty or loose - Repair or replace the spindle

Electrical Troubleshooting
Battery will not charge
Electrical wire connections are loose or corroded - Clean or tighten connections
Defective electrical terminal connectors - Change terminal connectors
Battery is worn - Battery replacement required
Starter turns slow
Low battery output voltage - Low battery charging, charge as required
Battery drains quickly - Service charging system or install new battery
Corroded battery terminals or disconnected wires - Connect wiring properly or install new terminals
Starter is not cranking
Battery is low or faulty - Replace or charge as required
Battery cables are disconnected or incorrectly connected - Check cables and connect as needed
Battery power is low - Battery is drained, charge it
Spark plug faulty or incorrectly gapped - Replace or clean and gap
Starter motor or solenoid failing - Repair starter or install a new solenoid




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