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Ford 6640 Tractor Troubleshooting

The Ford 6640 is a Powerstar 40 series utility tractor. This model was manufactured between 1991 and 1995. The Ford 6640 tractor is powered by 304 cubic inches (5 L) Ford Genesis four stroke 4-cylinder liquid-cooled diesel engine with a maximum power of 85 hp (62.5 kw) at 2200 rev/min.

The Ford 6640 is fitted with 4 transmission options: 8x2 EconoShift constant mesh transmission, 16x4 Dual power transmission, 12x12 Synchro shift transmission, and 16x16 Pulse command transmission. The maximum travel speed (forward/reverse): 19.2 mph (30.9 kph).

The open center hydraulic system includes a gear pump with rated fluid flow of 9.6 gpm (36.8 lpm). The hydraulic system pressure is 176 bar (2550 psi). The Ford 6640 is equipped with 7.50x16 front tyres and 16.9x30 rear tyres. The wheel base is 92.1" (2340 mm) for models with 2WD (4x2), and 93" (2360 mm) for models with 4WD (4x4).

Engine Troubleshooting
Diesel will not start or hard to start
Dirty fuel filter element - Clean or change the filter
Fuel shut-off valve closed - Open the fuel shut-off valve
Air in fuel lines - Bleed fuel lines
Clogged or damaged injectors - Check fuel injectors and replace if required
Faulty fuel injection pump - Replace injection pump or repair it
Low compression - Check and change damaged parts
Diesel stalls while running
Engine not warmed up - Warm up the engine
Air trapped in fuel system - Bleed air
Improper fuel injection - Fuel injection settings required
Fuel filter is dirty - Change the filter element
Fuel injectors are clogged or faulty - Check fuel injectors and replace if required
Diesel starts but then shuts off
Fuel injection pump timing is incorrect - Check and correct adjustments
Fuel filter is clogged - Change the filter element
Fuel injector nozzles are dirty or defective - Change injector nozzles
Fuel injection pump malfunctioning - Change or repair the pump
Clogged air cleaner - Change or service air cleaner element
Engine stalls at low idle speed
Incorrectly set low idle speed - Correct the settings
Damaged fuel injection pump - Rebuild or change fuel pump
Fuel injector nozzles are clogged or faulty - Replace fuel injector nozzles
Incorrect valve clearance - Adjustment procedure required
Engine overheated
Insufficient coolant fluid - Coolant needs to be refilled. Check the components of cooling system
Cooling system is clogged or cooling parts are worn - Replace faulty parts or service cooling system
Lack of engine oil - Fill up the oil to required level
Fan belt is defective or belt tension is not adjusted - Replace or adjust belt tension properly
Defective thermostat - Test thermostat opening temperature, replace as required
Diesel engine loses power
Faulty or dirty injectors - Check fuel injectors and replace if required
Fuel injection pressure is wrong - Adjust to proper pressure
Air filter element clogging - Service or replace the air filter
Dirty oil filter - Service or change engine oil filter element
Engine overload - Reduce the load or operate the tractor in lower gears
Improper valve clearance - Adjust valve clearance according to specifications
Low idle speed adjustment is incorrect - Correct low idle settings
Dirty fuel hoses or pipes - Clean fuel hoses and pipes
Low engine compression: Valves are broken or leaking - Replace the valves as required
Abnormal engine knocking or noise
Fuel injection pump timing is incorrect - Fuel pump timing settings need to be corrected
Fuel injector nozzles fault - Change or clean injector nozzles
Low engine oil level - Fill up the oil to required level
Engine is not fully warmed up - Normalize the engine temperature
Worn crankshaft or main bearings - Repair or replace defective parts
Broken or worn piston rings - Replace the piston rings as required
The flywheel to crankshaft bolts are loose - Tighten bolts as required
High oil consumption
Oil leaks: Defective seals or gaskets - Install new components
Oil viscosity is incorrect - Use oil of correct viscosity
Worn or stuck piston rings - Replace piston rings
Valve stems and guides are worn - Change the valves
Scuffed pistons or cylinder liners - Check liners and pistons, install new components as required

Electrical System Troubleshooting
Battery does not charge
Battery is defective - Battery change required
Damaged battery wiring harness - Inspect wiring for damage, replace or repair
Corroded or loose cables and terminals - Tighten or clean terminals and cables
Belt damage or incorrect belt tension adjustment - Replace belt or properly adjust belt tension
Starter turns slow
Low battery voltage - Battery is drained, recharge it
Battery is not holding charge - Service battery or change it
Bad battery cable harness - Inspect cables for malfunctions, repair or change
Loose or corroded terminals and cables - Service or tighten battery terminals and cables
Starter motor won't turn
Low battery power - Charge the battery
Discharged or faulty battery - Recharge or change battery
Defective starter motor - Repair or replace starter
Wiring is improperly connected or disconnected - Need to reconnect the wiring properly

Transmission Troubleshooting
Gear shift is hard
Clutch is unadjusted or worn - Adjust correctly or replace
Damaged or loose gear shift linkage - Change defective shift linkage
Damaged or worn shift forks - Change the shift forks
Worn gear shift mechanism - Replace worn components
Transmission fluid pressure is insufficient
Oil level is low - Correct the transmission oil level
Transmission fluid filter is dirty (if equipped) - Change or clean the transmission fluid filter
Relief valve failure - Install a new valve
Excessive transmission noise
Damaged or worn bearings - Install new bearings
Oil level is insufficient - Fill the transmission housing to proper oil level
Contaminated transmission fluid - Fill up with fresh transmission fluid
Defective gears or incorrect backlash - Replace gears or set backlash properly
Shift forks are damaged or worn - Change defective shift forks
External fluid leaks
Gaskets or seals are defective Install new components
Transmission case is cracked - Replace case or transmission assembly

Hydraulics Troubleshooting
Hydraulic system overheated
Incorrect hydraulic system pressure setting - Change the pressure settings
Faulty or incorrectly adjusted main relief valve - Adjust relief valve or change if required
Dirty hydraulic fluid - The fluid must be changed
Air in hydraulic system - Inspect the suction line, pump seals, and fittings
Hydraulic oil pressure is insufficient
Not enough hydraulic fluid in the system - Need to add fluid
Hydraulic oil filter element clogging - Install a new hydraulic filter element
Defective hydraulic pump - Check hydraulic pump flow and replace pump if necessary
Defective or incorrect setting hydraulic control valve block - Adjust properly or change
Hydraulic cylinder malfunction - Inspect cylinder parts for wear or damage and replace if required
Hydraulic pipes are leaking - Identify leaks in the system and repair it
3-point hitch lifts too slowly or can't lift
Lack of hydraulic oil - Add oil to the hydraulic system
Hydraulic oil is too cold - Allow oil to warm
Dirty hydraulic oil filter - Hydraulic filter maintenance required
Hydraulic pump malfunction - Check pump flow and install new pump if necessary
Defective or misadjusted main relief valve - Adjust or replace the relief valve
Hydraulic control valve block is not set properly or defective - Set correctly or replace
Hydraulic cylinder is faulty - Inspect cylinder parts for wear or damage and replace if required
Damaged or loose suction line - Tighten or change
Hitch does not lower or lowers very slowly
Hydraulic spool valve is not set properly or defective - Set properly or replace
Broken hydraulic cylinder - Inspect cylinder parts for wear or damage and replace if required
Lift arm shaft is damaged - Install a new shaft
The hitch has any internal mechanical damage - Replace faulty or worn hitch parts
Hitch jerks when drop or lift
Air in hydraulic system - Check the suction line, pump seals, and fittings
Hydraulic oil is dirty - Hydraulic oil change required
Hydraulic pump failure - Test the pump flow rate and install new pump if required
Hydraulic control valve is defective or set improper - Replace or set properly
Hydraulic cylinder is defective - Check the cylinder components for damage or wear and change if necessary

Steering System Troubleshooting
Steering wheel is hard to turn
Steering column is defective or incorrectly installed - Steering column must be installed correctly or replaced
Air enters in steering system - Bleed air
Steering filter clogging - Clean steering filter element
Improper toe-in adjustment - Adjust toe-in properly
Tires are not correctly inflated - Inflate tires as necessary
Steering pump is worn - Repair or change steering pump
Damaged or worn power steering control unit - Inspect and replace as required
Faulty or stuck relief valve - Service or replace the relief valve
Low steering oil level - Fill up the steering oil
Steering system oil leak - Tighten joints of hydraulic pipes and hoses in steering system
Steering wheel has too much free-play
Steering column coupling or shaft is extremely worn out - Change faulty component
Worn or defective power steering control unit - Replace or repair steering unit as required
Steering pump stopped working - Repair or replace steering pump
Worn or faulty steering tie-rod ends or linkage - Change damaged part
Tractor pulls to left or right
Tire pressure is improper - Inflate the tires properly
Incorrect toe-in - Adjust toe-in correctly
Steering tie-rod ends or linkage are defective - Change failed component
Power steering control unit is defective or worn - Repair or change the steering unit
Defective steering cylinder - Repair or change hydraulic steering cylinder
Improperly adjusted or worn front hub bearings - Adjust correctly or change bearings




Farm Tractors Technical Specifications
JD 1026R JD 3650 JD 6400 JD 7810
FORD 1320 FORD 2810 FORD 3930 FORD 5600
MF 250 MF 690 MF 3060 MF 6180
NH TC48DA NH M100 NH T7550 NH 8560
CASE IH 495 CASE IH 1255XL CASE IH 2140 CASE IH 2294