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John Deere L120 Troubleshooting
The
John Deere L120 lawn tractor was manufactured between 2003 and 2005. The John
Deere L120 tractor can be powered by two engines: 40.03 cu.in (656 cc) Briggs
and Stratton 406777 4-cycle V-twin cylinder OHV vertical-shaft air-cooled
gasoline engine with a rated power of 20 hp (15.4 kW), or 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 22 hp (16.4 kW).
The John Deere L120 is equipped with Tuff Torq K46 HD belt-driven
hydrostatic transmission with foot-controlled variable speed drive. Max
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, wet
disc brakes, 16x6.50-8 front tires, and 22x9.50-12 rear tires.
The wheelbase is 49" (1240 mm). The John Deere L120 is compatible with a
42" mid-mount 2-blade mower deck with cutting height of 1.0-4.0" (25-102
mm) and manual lift system, 42" front-mount dual-stage snowblower with
clearing height of 21" (530 mm), and 46" front blade with lift height of
6.5" (160 mm).
| Engine Troubleshooting |
| Engine starts hard or will not start |
| No fuel in fuel tank - Fill it up |
| Wrong grade of gasoline - Use quality fuel |
| Clogged fuel system - Remove clogging |
| Loose or disconnected spark plug wire - Check the spark plug wire connection, repair or replace |
| Spark plug is damaged - Change spark plug as required |
| Plugged fuel filter - Change fuel filter |
| Brake pedal not depressed - Press the brake pedal |
| Carburetor not adjusted - Adjust according to instructions |
| Engine has bad compression - Check cylinder block and change wear parts |
| Not adjusted or damaged throttle cable - Change cable or adjust properly |
| Air intake grill is clogged - Wash or clean as required |
| Ignition system malfunction - Inspect ignition system and change failed components |
| Stuck or defective throttle cable - Replace or service the cable |
| Air filter element is plugged - Change or service air filter |
| Fuel pump is dirty or defective - Service or change fuel pump |
| Engine starts but then stalls |
| Damaged spark plug - Replace spark plug |
| Carburetor is faulty or clogged - Replace or service carburetor |
| Ignition coil is not working - Change ignition coil as required |
| Broken or bad valve springs - Valve springs need to be changed |
| Valves sticking - Clean the valves |
| Lack of engine oil - Check and refill engine oil |
| Engine is under excessive load - Reduce the load |
| Air intake grill is clogged - Need to clean or wash |
| Carburetor fuel mixture is too lean - Set the carburetor correctly |
| Wrong ignition timing - Set the ignition timing properly |
| Valve setting is improper - Adjust valves correctly |
| Stale fuel - Use proper fuel |
| Engine is under excessive load - Reduce the load |
| Engine oil level is insufficient - Fill up the oil to required level |
| Low idle speed set incorrectly - Correct the settings |
| Dirty or damaged fuel pump - Test fuel pump and change if necessary |
| Crankshaft or main bearings are worn out - Install new parts as as required |
| Valve clearance is improper - Need to adjust valve clearance |
| Damaged cylinder bore or piston rings - Change defective components |
| Carburetor is dirty or improperly adjusted - Service or properly adjust carburetor |
| Plugged air filter - Clean or change air filter |
| Fuel pump is clogged or faulty - Check fuel pump and change if required |
| Ignition system is defective - Check ignition system and replace faulty parts |
| Cylinder head gasket is damaged - Replace the head gasket |
| Valves are burned or stuck - Replace or service valves |
| Worn or defective push rod - Push rod needs to be changed |
| Cylinder block components are damaged - Change defective components |
| Engine uses too much fuel |
| Choke opening is not full - Replace or adjust choke cable |
| Incorrect adjustment of carburetor main jet - Adjust it correctly |
| Loose or faulty spark plug - Tighten or change the spark plug |
| Stuck, worn, or burned valves - Replace or clean valves |
| Rings, sleeve, or piston are damaged - Change faulty components |
| Excessive valve clearance - Adjust valve clearance according to specifications |
| Damaged gaskets or seals - New components need to be installed |
| Valve guides and stems are worn - Need to replace the valves |
| Worn or stuck piston rings - Install new piston rings |
| Cylinder liner or piston is worn - Inspect liner and piston, change as necessary |
| Plugged breather pipe or hose - Replace or clean |
| Hydrostatic Transmission Troubleshooting |
| HST transmission makes noise |
| Defective or not adjusted speed control pedal linkage - Change or adjust linkage |
| Excessive loading - The load should be reduced |
| Transmission fluid is dirty or fluid level is too low - Add fluid to correct level or fill the transmission with fresh fluid |
| Worn or defective parts of transmission - Check transmission components and change if necessary |
| Corroded or worn shift linkage - Lubricate or change linkage |
| Hydrostatic pump is worn or stuck - Replace or repair pump |
| Faulty or misadjusted transmission shift control parts - Adjust properly or change |
| Insufficient transmission fluid - Check and refill the transmission fluid |
| Worn or damaged drive sheave - Replace sheave |
| Unadjusted or broken shift linkage - Adjust properly or change linkage |
| Worn or out of adjustment speed control linkage - Adjust or replace linkage |
| Transmission seals or gaskets are broken - Seals and gaskets need to be replaced |
| Final drive shaft leaks - Replace shaft seals |
| Cracked transmission case - Replace defective case or transmission assembly |
| Mower Deck Troubleshooting |
| Mower vibrates too much |
| Mower deck drive sheave is clogged or worn - Clean or change sheave |
| Drive belt is defective or loose - Install a new belt or adjust belt tension |
| Mower blades are unbalanced or bent - Balance or replace blades |
| Blade bolts are not tightened well - Tighten bolts as required |
| Discharge chute regular clogging |
| Mowing speed is too high - Use a lower speed |
| Grass is too long - Use a lower cutting height |
| Low engine speeds - Open choke fully |
| Cutting height is too low - Change cutting height adjustment |
| Improper drive belt installation - Install drive belt as required |
| Lawn mower leaving uncut grass |
| Deck is plugged with grass - Clean out the mower deck |
| Blades are not sharp - Need to sharpen the blades |
| Damaged or worn blades - Replace the blades |
| Mowing speed is too high - Operate at slower speed |
| Cutting level is too low - Change cutting height adjustment |
| Full bagger - Remove grass from bagger |
| Blades are scalping the grass |
| Bumpy or not smooth lawn - Level the lawn |
| Cutting height is too low - Change cutting height adjustment |
| High ground speed - Use a lower speed |
| Deck level is not correct - Level the deck properly |
| Damaged or bent blades - Blades must be changed |
| Low tire pressure - Correct tire pressure |
| Incorrect tire pressure - Inflate tires as required |
| Improperly leveled mower deck - Deck needs to be adjusted properly |
| Blades are too dull - Blades need to be sharpened |
| Worn or defective blades - Blades must be changed |
| Discharge chute is plugged - Need to clean the mower deck |
| Deck shell is broken - Replace or rebuild mower deck |
| Bent or loose mower spindle - Change or repair the spindle |
| Electrical Troubleshooting |
| Battery cannot be charged |
| Corroded or loose wire connections - Clean or tighten connections |
| Faulty battery terminal connectors - Replace terminal connectors |
| Battery faulty cell - Battery change required |
| Low battery output - Recharge the battery |
| Battery runs out quickly - Service charging system or change battery |
| Terminals are faulty or battery cables are disconnected - Check cables and change or clean terminals |
| Battery is low or faulty - Change or recharge battery |
| Battery wiring is disconnected or improperly connected - Inspect wiring and connect as required |
| Low battery power - Low battery charging, charge as required |
| Spark plug faulty or incorrectly gapped - Clean, gap or replace spark plug |
| Solenoid or starter motor failure - Repair starter or replace solenoid |
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| Lawn and Garden Tractors Technical Specs |
