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Gehl 6635DXT Troubleshooting

The Gehl 6635 DXT skid steer loader driveline system components: a 187 cu.in (2.9L) Deutz BF4M1011F 4-cylinder turbo liquid-cooled diesel engine with a rated power of 75 hp (56 kW), and 1-speed or 2-speed transmission. The hydraulic system has a pump with a rated capacity of 23 gal/min (87.1 l/min). The system relief pressure is 3000 psi (207 bar). The Gehl 6635DXT is equipped with a radial-lift loader boom, 100H roller chains, and 12x16.5 or 33-15.5x16.5 tires. The skid steer loader has a max lift height of 122.7" (3120 mm) to hinge pin and dump height of 93.7" (2380 mm). The rated operating capacity is 2350 lbs (1065 kg), and tipping load is 4700 lbs (2130 kg).

Engine Troubleshooting

Diesel engine hard to start or doesn't start
Air in fuel tank - Bleed fuel tank.
Clogged fuel filter - Change filter element.
Damaged or dirty injection nozzles - Clean or change injection nozzles.
Water in the fuel system - Change fuel and repair fuel system.
Valve clearance is not correct - Have it adjusted.
Fuel injection pump is damaged - Change or repair the pump.

Engine starts and stops suddenly
Plugged air cleaner - Service or replace air cleaner.
Fuel filter element clogging - Replace filter element.
Fuel injection pump has loose connections - Tighten the connections.
Fuel injectors are faulty or clogged - Inspect fuel injectors and change as required.
Fuel injection pump failure - Repair or replace injection pump.

Engine stalls after running
Low coolant temperature - Warm up the engine.
Clogged fuel filter - Replace the filter element.
Air in the fuel pipes - Bleed the fuel pipes.
Dirty or faulty injection nozzles - Install a new kit of correctly balanced nozzles.
Fuel injection pump timing is not adjusted - Use the correct fuel injection pump timing adjustment.

Engine stops when idling
Low idle speed set incorrectly - Adjust low idle speed.
Fuel injection pump is defective - Replacement or repair required.
Fuel injector fault - Clean or replace fuel injectors.
Incorrect valve clearance - Adjustment procedure required.

Lack of engine power
Plugged air filter - Install new air filter element.
Fuel injection nozzles fault - Clean or replace injection nozzles.
Fuel injection pressure is wrong - Check the fuel injection pressure and adjust if necessary.
Improper valve clearance - Correct valve clearance.
Incorrectly set low idle speed - Test and adjust.
Dirt in the fuel hoses or lines - Fuel lines and hoses need to be cleaned.
Worn cylinder head gasket - Install a new gasket.
Piston rings are defective or leaking - Replace the piston rings as required.

Engine overheated
Lack of engine coolant - Top up coolant fluid and check system for leaks.
Lack of engine oil - Fill the crankcase with engine oil.
Defective radiator cap or clogged radiator fins - Install new cap or clean radiator.
Fan belt is broken or worn - Belt change is required.
Engine overloaded - Reduce engine load.

Oil pressure too low
Low crankcase oil level - Check and refill the oil.
Plugged engine oil filter - Service or replace engine oil filter.
Different type of engine oil - Use correct viscosity oil.
Incorrect oil clearance in main bearing - Bearing needs to be changed.
Oil pump is worn or damaged - Install a new pump.

Engine noise or knocking
Engine oil level is low - Fill the crankcase with engine oil.
Low coolant temperature - Warm up the engine.
Improper setting of fuel injection pump timing - Adjust fuel injection pump as required.
Low idle speed set incorrectly - Adjust the low idle speed.
Damaged or clogged injectors - Change or clean fuel injectors.
Connecting rod is defective or misaligned - Align or change connecting rod.
Pistons are scored or worn - Have pistons replaced.

Drive System Troubleshooting

Machine is not moving in one direction or either direction
Low hydraulic fluid level - Check and refill the hydraulic fluid.
Drive chain failure - Check drive chain and change faulty components.
Input drive shaft is defective - Repair or install a new drive shaft.
Relief valver is broken - Repair or replace.
Hydraulic filter or suction line is plugged - Service suction line or change hydraulic filter.
Foot or hand controls are defective - Repair or change.
Defective drive pump or motor - Inspect and change as required.

Power is too low
Hydraulic oil filter is dirty - Change or clean hydraulic filter.
Relief valve is open or defective - Change or close relief valve.
Transmission parts are damaged or faulty - Inspect and change faulty parts.
Damaged input drive shaft - Replace drive shaft.
Air in the hydraulic system - Need to bleed air.

Drive system overheating
Hydraulic fluid is insufficient - Fill the system to proper hydraulic fluid level.
Hydraulic fluid filter is plugged - Check, clean, or replace as required.
Defective or worn relief valve - Repair or install a new relief valve.
Hydraulic motor or drive pump failure - Replace or repair faulty component.
Clogged hydraulic oil cooler - Clean cooling fins as required.
Drive system overload - Reduce the load.

Drive system is noisy
Oil viscosity is wrong - Drain and refill with proper oil.
Air in the hydraulic system - Need to bleed air.
Hydraulic motor or drive pump failure - Change or repair faulty component.
Worn or damaged mechanical components of drive system - Check drive system and change faulty parts.

Hydraulics Troubleshooting

Hydraulic system has overheating
Hydraulic pressure is not correct - Correct adjustment is required.
Main relief valve failure or improper setting - Adjust or replace the relief valve.
Hydraulic oil is dirty - Hydraulic oil change required.
Lack of hydraulic fluid - Check and refill the hydraulic fluid.
Faulty hydraulic oil pump - Install new pump or repair it.

Lift arm fails to drop or lift
Defective lift controls - Replace or repair.
Damaged hydraulic oil pump - Install new pump or repair it.
Faulty hydraulic control valve - Repair or change hydraulic valve.
Broken hydraulic cylinder - Replace or repair boom cylinder.
Low hydraulic fluid level - Add fluid as required.

Bucket tilt does not work
Bucket tilt controls are damaged - Change or repair.
Defective hydraulic pump - Repair or replace pump if necessary.
Hydraulic control valve failure - Repair or replace the valve.
Hydraulic bucket cylinder not working - Change or repair cylinder.
Low hydraulic oil level - Check and refill the hydraulic oil.

Boom or bucket is working slowly
Defective hydraulic pump - Check pump flow and change pump if necessary.
Oil leaks from hydraulic cylinder - Cylinder seals need to be replaced.
Hydraulic oil is insufficient - Fill the system to proper hydraulic oil level.
Hydraulic control valve is not set properly or defective - Set properly or repair.
Hydraulic pressure has dropped - Adjust pressure correctly.

Bucket or boom is jerky
Air in hydraulic system - Air bleeding is required.
Hydraulic oil filter element is dirty - Service or change the hydraulic filter.
Hydraulic oil contamination - Change hydraulic oil.
Scored cylinder tube or rod - Change damaged component.

Hydraulic pump is excessively noisy
Hydraulic leakage or low oil level - Top up hydraulic oil or remedy leakage in system.
Hydraulic filter is dirty - Change or clean oil filter.
Clogged suction line - Clean suction line as required.
Air in hydraulic pump - Remove air from hydraulics.
Pump components are damaged - Rebuild or change hydraulic pump.

Electrical Troubleshooting

Battery won’t charge
Wiring connections are corroded or loose - Tighten or service connections.
Faulty battery terminal clamps - Terminal clamps need to be replaced.
Battery dead cell - Install a new battery.
Loose or defective belt - Change belt or adjust belt tension.

Starter turning slow
Low battery output voltage - Battery is drained, recharge it.
Battery discharges quickly - Battery needs to be serviced or replaced.
Disconnected battery cables or bad terminals - Connect wiring correctly or install new terminals.

Starter motor won't turn
Battery is discharged or defective - Recharge or change battery.
Wiring is incorrectly connected or disconnected - Inspect wiring and connect correctly.
Battery power is low - Battery is drained, recharge it.
Damaged starter motor - Starter should be replaced.