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Gehl 3935 Troubleshooting

The Gehl SL 3935 skid steer loader driveline system components: a 100.2 cu.in (1.6L) Yanmar 3TNV88 3-cylinder naturally aspirated liquid-cooled diesel engine with a rated power of 36.7 hp (27.4 kW), and 1-speed hydrostatic transmission. The hydraulic system has a pump with a rated capacity of 14.5 gal/min (55 l/min). The system pressure is 2750 psi (190 bar). The Gehl SL 3935 is equipped with a radial-lift loader boom, 80K drive chains, and 27x10.5x15 tires. The skid steer loader has a max lift height of 110" (2795 mm) to hinge pin and dump height of 86.3" (2190 mm). The rated operating capacity is 1260 lbs (572 kg), and tipping load is 2520 lbs (1145 kg).

Engine Troubleshooting

Engine starts hard or won't start
Air trapped in fuel system - Bleed air.
Fuel filter plugged - Replace filter element.
Dirty or damaged injection nozzles - Test injection nozzles and change if necessary.
Water in the fuel system - Change fuel and repair fuel system.
Incorrect valve clearance - Correct valve clearance.
Fuel injection pump damage - Replace injection pump or repair it.

Engine starts but then stalls
Dirty air cleaner - Service or replace air cleaner.
Fuel filter element clogging - Replace the filter element.
Fuel injection pump has loose connections - Tighten the connections.
Fuel injectors are faulty or clogged - Replace or clean fuel injectors.
Fuel injection pump is damaged - Replacement or repair required.

Engine stalls during operation
Engine is cold - Engine is not warmed up to the required temperature.
Fuel filter is plugged - Install new filter element.
Air in the fuel lines - Bleed the fuel lines.
Fuel injection nozzles are clogged or faulty - Inspect nozzles and replace if necessary.
Timing of fuel injection pump is incorrect - Check the fuel injection pump timing adjustment.

Engine stops at low idle speed
Incorrect low idle setting - Correct the settings.
Fuel injection pump is broken - Install a new fuel pump or repair.
Defective fuel injectors - Inspect fuel injectors and change as required.
Excessive valve clearance - Have it adjusted.

Engine lacks power
Air filter is plugged - Clean or change filter.
Faulty fuel injection nozzles - If necessary, replace with a new nozzle.
Fuel injection pressure is incorrect - Test fuel injection pressure and adjust it correctly.
Improper valve clearance - Adjust valve clearance.
Wrong adjustment of low idle speed - Correct low idle adjustment.
Clogged fuel hoses or lines - Fuel lines and hoses need to be cleaned.
Cylinder head gasket is defective - Install new cylinder head gasket.
Piston rings are worn or damaged - Replace the piston rings as required.

Engine overheating
Insufficient coolant - Add coolant and check the components of cooling system.
Engine oil level is low - Need to add engine oil.
Clogged radiator fins or damaged radiator cap - Change cap or clean radiator.
Fan belt is broken or worn - Fan belt must be replaced.
Engine overloaded - Load reducing is recommended.

Oil pressure is low
Oil level is low - Add oil as required.
Clogged oil filter element - Replace or clean engine oil filter element.
Incorrect oil viscosity - Fill up with the proper oil viscosity.
Incorrect oil clearance in main bearing - Change bearings.
Oil pump is defective - Repair or change.

Abnormal engine knocking or noise
Not enough engine oil - Need to add engine oil.
Engine not warmed up - Engine is not warmed up to the required temperature.
Incorrect adjustment of fuel injection pump timing - Adjust as recommended.
Incorrect low idle setting - Adjust low idle speed.
Fuel injectors are faulty or clogged - Replace or clean fuel injectors.
Faulty or misaligned connecting rod - Align or change connecting rod.
Pistons are broken or worn - Replace the pistons as required.

Drive System Troubleshooting

Machine will not move in either direction or one direction
Insufficient hydraulic fluid - Check and refill the hydraulic fluid.
Drive chain malfunction - Inspect drive chain and replace defective components.
Relief valve is damaged - Service or change relief valve.
Dirty suction line or hydraulic filter - Check, clean, or change if necessary.
Foot or hand controls are damaged - Repair or change.
Drive motor or pump is defective - Repair or replace faulty component.

Reduced power
Clogged hydraulic oil filter - Check, clean, or replace as required.
Opened or worn relief valve - Close or replace relief valve.
Worn or faulty transmission components - Inspect and replace defective parts.
Stuck input drive shaft - Repair or install a new drive shaft.
Air in the hydraulic system - Air bleeding is required.

Overheated drive system
Hydraulic oil is insufficient - Need to add oil.
Plugged hydraulic fluid filter - Check, clean, or change as necessary.
Worn or defective relief valve - Repair or change.
Drive pump or hydraulic motor malfunction - Change or repair faulty component.
Hydraulic oil cooler is dirty - Clean the cooling fins.
Overloaded drive system - Reduce loading.

Drive system makes excessive noise
Oil viscosity is incorrect - Use the specified type of oil.
Air leaks in hydraulic system - Air bleeding is required.
Drive pump or hydraulic motor is damaged - Inspect and replace as necessary.
Worn or defective mechanical parts of drive system - Check the components for defect or damage and change if necessary.

Hydraulics Troubleshooting

Hydraulic system overheated
Hydraulic pressure is incorrect - Adjust pressure correctly.
Unadjusted or defective main relief valve - Replace or set up the relief valve.
Hydraulic oil is contaminated - Fill up with fresh hydraulic oil.
Hydraulic fluid level is low - Need to add fluid.
Hydraulic pump is worn - Install new pump or repair it.

Lift arm does not lower or raise
Damaged lift controls - Repair or change.
Hydraulic pump is broken - Replace or repair pump if necessary.
Hydraulic control valve failure - Repair or replace the valve.
Broken hydraulic cylinder - Repair or replace hydraulic cylinder.
Insufficient hydraulic oil - Fill the system to proper hydraulic oil level.

Bucket fails to tilt
Faulty bucket tilt controls - Check and repair as required.
Hydraulic pump failure - Install new pump or repair it.
Damaged hydraulic control valve - Repair or change the valve.
Defective bucket cylinder - Replace or repair cylinder.
Hydraulic fluid is insufficient - Fill up the hydraulic fluid.

Bucket or lift arm is moving slowly
Faulty hydraulic oil pump - Check pump flow and install new pump if necessary.
Oil leaks from hydraulic cylinder - Cylinder seals need to be replaced.
Insufficient hydraulic oil - Fill the system to proper hydraulic oil level.
Hydraulic control valve is not set properly or defective - Repair or set properly.
Hydraulic system loosing pressure - Adjust pressure correctly.

Lift arm or bucket movements are jerky
Air in hydraulic system - Need to bleed air.
Hydraulic oil filter element is clogged - Replace or clean the filter.
Hydraulic oil contamination - Fill up with fresh hydraulic oil.
Cylinder rod or tube is scuffed - Replace damaged component.

Hydraulic pump is noisy
Hydraulic system leaking or not enough oil - Add hydraulic oil or correct system leaks.
Hydraulic filter clogging - Clean or replace the filter.
Suction line is clogged - Suction line needs to be cleaned.
Pump sucks air - Remove air from hydraulics.
Damaged pump components - Rebuild or install new pump.

Electrical Troubleshooting

Battery cannot be charged
Wiring connections are corroded or loose - Tighten or service cable connections.
Defective battery terminal clamps - Change terminal clamps.
Battery faulty cell - Change the battery.
Belt is loose or defective - Adjust belt tension or change the belt.

Starter cranks slowly
Battery voltage is low - Recharge the battery.
Battery won’t hold charge - Service battery or change it.
Battery cables are disconnected or terminals are faulty - Connect wiring correctly or install new terminals.

Starter does not work
Battery is discharged or worn - Recharge or change battery.
Wiring is improperly connected or disconnected - Check wiring and connect properly.
Battery capacity is low - Battery is drained, charge it.
Starter motor is defective - Starter should be changed.