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John Deere LA105 Troubleshooting

The John Deere LA105 lawn tractor was manufactured from 2008 to 2010. The JD LA105 driveline consists of a Briggs and Stratton 31P677 4-cycle single cylinder OHV vertical shaft air-cooled gasoline engine and Dana 4360 belt-driven gear transmission with 5 forward and 1 reverse gears.

A 30.6 cu.in (501 cc) engine has a cylinder bore of 3.56" (91 mm), piston stroke of 3.06" (78 mm), and rated power of 19.5 hp (14.5 kW). Max. forward speed - 5 mph (8 km/h), maximum reverse speed - 2.3 mph (3.7 km/h).

The lawn tractor is equipped with a manual steering system, disc brakes, 15x6.00-6 front tires, and 20x8.00-8 rear tires. The wheelbase is 49" (1240 mm). The John Deere LA105 is compatible with a 42" mid-mount 2-blade mower deck with cutting height of 1-4" (25-102 mm), 44" front-mount 2-stage snowblower with clearing height of 18" (450 mm), and 46" front blade with manual lifting system.

Engine Troubleshooting
Engine hard to start or will not start
Empty gas tank - Fill it up
Improper fuel grade - Change gasoline
Dirty fuel system - Check and clean
Defective spark plug wire connection - Inspect spark plug wiring connection, change or repair
Faulty spark plug - Change spark plug as required
Plugged fuel filter - Fuel filter needs to be replaced
Brake pedal not depressed - Press the brake pedal
Carburetor is not working properly - Inspect and adjust
Bad compression - Check and change damaged parts
Throttle cable is adjusted improperly or worn - Adjust properly or replace the cable
Engine runs roughly
Cooling fins are clogged - Need to clean or wash
Ignition system is defective - Check ignition and replace faulty components
Defective or stuck choke cable - Change or service the cable
Air filter element is plugged - Clean or replace air filter
Fuel pump is clogged or faulty - Service or change fuel pump
Engine starts but immediately stops
Spark plug is damaged - Install new spark plug
Carburetor is dirty or defective - Service or change carburetor
Faulty ignition coil - Replace ignition coil as necessary
Valve springs are worn or loose - Replace valve springs
Stuck valves - Valves must be cleaned
Engine overheats
Engine oil level low - Add oil to the engine crankcase
Excessive engine load - Load reducing is recommended
Cooling fins are blocked - Clean and wash as required
Carburetor is running lean - Make the correct settings
Incorrect ignition timing - Set the ignition timing properly
Valve setting is incorrect - Adjust valves as required
Engine knocking or noise
Stale or low octane fuel - Use proper fuel
Engine is under excessive load - Load reducing is recommended
Engine oil level is low - Check oil level and add oil as required
Wrong adjustment of low idle speed - Correct idle settings
Fuel pump is clogged or faulty - Clean or replace fuel pump
Worn main bearings or crankshaft - Crankshaft or bearings need to be replaced
Excessive valve clearance - Adjust valve clearance
Cylinder bore or piston rings are worn - Replace faulty components
Engine power is too low
Dirty or improperly adjusted carburetor - Adjust the carburetor properly or clean it
Air filter element is plugged - Change or service air filter
Clogged or damaged fuel pump - Test fuel pump and replace if necessary
Ignition system malfunction - Inspect ignition system and change failed components
Defective cylinder head gasket - Cylinder-head gasket replacement required
Burned or stuck valves - Clean or replace valves
Push rod is bent or worn - Change push rod
Cylinder block components are faulty - Replace defective components as required
Engine using too much gasoline
Choke did not open fully - Change or adjust choke cable
Improper adjustment of carburetor main jet - Adjust it correctly
Spark plug is loose or defective - Tighten or replace spark plug
Worn, stuck, or burned valves - Replace or service valves
Worn piston, rings, or sleeve - Change faulty components
Improper valve clearance - Adjust to proper valve clearance
Engine consuming too much oil
Damaged gaskets or seals - New components need to be installed
Damaged valve guides or valve stems - Change the valves
Piston rings are stuck or broken - Replace piston rings
Piston or cylinder liner is scored - Inspect piston and liner, change as required
Blocked breather pipe or hose - Clean or replace

Transmission Troubleshooting
Difficult to shift gears
Loose or broken gear shift linkage - Change defective shift linkage
Shift forks are bent or worn out - Replace the shift forks
Gear shifting mechanism is worn - Change worn components
Transmission makes noise
Transmission oil level is low - Fill the transmission housing to proper oil level
Transmission oil is dirty - Transmission oil change required
Worn gears or damaged bearings - Replace gears or bearings
Transmission jumping out of gear
Bent or incorrectly installed shift lever - Reinstall the lever properly or change it
Gears are worn or damaged - Change gears
Shift forks or shift rods are worn - Change defective forks or rods
Transmission slipping
Drive shaft/belt is worn or incorrectly adjusted - Install a new shaft/belt or adjust it
Improper brake/clutch adjustment or damaged brake/clutch - Replace brake/clutch or adjust it
Drive sheave is worn or faulty - Replace sheave

Mower Deck Troubleshooting
Mower vibration is excessive
Damaged or clogged mower drive pulley - Clean or change pulley
Drive belt is damaged or loose - Install a new belt or adjust belt tension
Mower blades are warped or not balanced - Balance or change blades
Loose blade bolts tightening - Bolts should be tightened
Constant clogging of discharge chute
Mowing speed is too high - Select a lower speed
Grass is too long - Must be set to low cutting height
Reduced engine rpm - Adjust carburetor to higher rpm
Cutting height is too low - Use correct cutting height
Incorrect mower drive belt installation - Install drive belt correctly
Mower leaving random uncut of grass
Clogged mower deck - Check cutting deck and clean as necessary
Not sharp blades - Sharpen the blades
Worn or damaged blades - Install new blades
High ground speed - Need to slow down
Cutting height is too low - Use a higher cutting height
Bagger is overfilled - Remove grass from bagger
Blade scalped grass
Lawn is bumpy or not smooth - Lawn leveling required
Cutting level is too low - Adjust mower to higher cutting height
High mowing speed - Use a slower speed
Mower deck is not leveled properly - Adjust the level of mower deck correctly
Blades are bent or worn - Blades must be changed
Tires are not properly inflated - Inflate tires as required
Mower cuts uneven
Low tire inflation - Inflate tires as required
Mower deck is not leveled properly - Adjust mower deck level properly
Blades are excessively dull - Need a blade sharpening
Damaged or worn blades - Replace the blades
Discharge area is clogged - Clean out the mower deck
Deck shell is damaged - Repair or replace the deck
Loose or defective mower spindle - Repair or replace the spindle

Electrical Troubleshooting
Battery won’t charge
Electrical cable connections are corroded or loose - Clean or tighten wiring connections
Battery terminal connectors are faulty - Install new terminal connectors
Bad cell in battery - Change the battery
Starter turns slow
Battery power is low - Battery needs to be recharged
Battery will not hold charge - Service charging system or replace battery
Bad battery terminals or disconnected wiring - Check wiring and clean or replace terminals
Starter does not work
Battery is drained or worn - Recharge or change battery
Battery cables are disconnected or incorrectly connected - Check cables and connect as needed
Low battery output - Charge the battery
Improperly gapped or dirty spark plug - Clean, gap or replace spark plug
Solenoid or starter motor failure - Change solenoid or repair starter




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