John Deere 6068HF120 Engine

⚠ Valve clearance must be checked and adjusted with engine cold.

Tools: JDE83 or JDG820 Flywheel Turning Tool, JDE81-4 Timing Pin, Feeler gauge

1. Disconnect negative battery terminal.
2. Remove rocker arm cover and crankcase ventilator tube.
3. Remove timing hole plugs; rotate engine to No. 1 TDC compression.
4. Insert JDE81-4 timing pin in flywheel.
5. Check intake and exhaust valve clearances with engine cold.
6. Loosen jam nut and adjust screw until feeler gauge drags slightly.
7. Hold screw, tighten jam nut to 27 N•m (20 lb-ft), recheck clearance.
8. Repeat for remaining valves per 4- or 6-cylinder sequence.

⚠ Do not pry against alternator rear frame.

Tools: JDG1341 belt tension gauge

1. Install JDG1341 belt tension gauge halfway between pulleys.
2. Loosen cap screws B and C.
3. Slide alternator or tensioner bracket by hand to remove slack.
4. Pry outward on alternator front frame or tensioner bracket to stretch belt.
5. Stretch until specified tension is achieved.
6. Tighten cap screws B and C.
7. Run engine ten minutes and recheck used belt tension.

⚠ Explosive release of fluids from pressurized cooling system can cause serious burns.

Tools: D05104ST Tester

1. Remove radiator cap and attach to D05104ST tester.
2. Pressurize cap to 70 kPa (0.7 bar) (10 psi).
3. Gauge should hold pressure for 10 seconds.
4. Retest cap turned 180 degrees to verify.
5. Connect gauge and adapter to radiator filler neck.
6. Pressurize system to 70 kPa and check for leaks.

⚠ Do not let thermostat or thermometer rest against container side or bottom.

Tools: Thermometer, Container

1. Remove thermostat(s) and inspect for corrosion or damage.
2. Suspend thermostat and thermometer in water.
3. Stir water as it heats and observe opening action.
4. Compare opening temperatures with specification chart.
5. Remove thermostat and observe smooth closing as it cools.
6. Replace defective thermostat; replace dual thermostats as matched set.

⚠ Towing with a non-matching device can cause serious accidents.

1. Lock wheels to stop trailer moving.
2. Lift rear trailer supports and lock them.
3. Release parking brake.
4. Release draw bar arm locking levers and adjust ring to vehicle hook height.
5. Hitch trailer and remove wheel locks.
6. Lift front wheel fully using its handle.
7. Connect trailer electrical circuit to tow vehicle.
8. Hook handbrake safety wire onto tow vehicle hook.

Tools: fork lift truck with arms longer than frame width

1. Position fork lift arms under frame cross beams only.
2. Lift and handle equipment carefully.
3. Set down generating set in unloading position.

⚠ Never carry out work on a generating set suspended on a lifting device only.

Tools: crane, slings, lifting beam, safety hook, shackles

1. Attach lifting slings to the set's designated lifting rings.
2. Hang slings carefully and check they are correctly attached.
3. Check equipment is solid before lifting.
4. Lift the generating set carefully.
5. Direct and stabilise the set toward the chosen position.
6. Set down carefully while continuing to position it.
7. Release slings, then detach and remove lifting rings.

⚠ Keep sparks and flames away from battery.

Tools: Midtronics, Wega, or similar battery tester, hydrometer

1. Visually inspect tray, terminals, and electrolyte level.
2. If electrolyte below prescribed level, add water and charge 4-5 hours.
3. Check electrolyte density; above 1.22 kg/l proceed to electrical test.
4. If density is below 1.22 kg/l or cell variation exceeds 50 g/l, recharge or replace.
5. Use Midtronics, Wega, or similar tester for quick electrical performance test.
6. Replace battery if tester gives negative result.

⚠ Escaping fluid under pressure can penetrate skin.

1. Loosen air bleed vent screw two full turns on filter base.
2. Operate supply pump primer lever until fuel is free of bubbles.
3. Tighten bleed plug; continue priming until resistance is felt.
4. Push hand primer inward toward engine.
5. Start engine and check for leaks.

⚠ Do not overtighten filter element.

Tools: filter wrench

1. Run engine about 5 minutes to warm oil; shut off.
2. Remove oil pan drain plug and drain crankcase oil while warm.
3. Remove and discard oil filter element using a filter wrench.
4. Clean filter mounting pad and remove old packing.
5. Oil new packing and install new filter; hand tighten 3/4-1-1/4 turn after contact.
6. Install drain plug with new seal.
7. Fill crankcase with correct oil; do not overfill.
8. Start engine, check leaks, stop, and check oil level after 10 minutes.

Tools: Breaker bar, Socket, Torque wrench

1. Release belt tension using breaker bar and socket.
2. Remove belt from pulleys and release tension arm.
3. Mark swing arm (A) and mounting base 21 mm away (B).
4. Rotate swing arm with torque wrench until marks align.
5. Record torque and compare with specification.
6. Replace tensioner assembly as required.

⚠ The air intake system must not leak; leaks may cause internal engine damage.

1. Inspect all intake hoses for cracks; replace as necessary.
2. Check clamps connecting air cleaner, engine, and turbocharger; tighten as necessary.
3. Inspect rubber dust unloader valve for cracks or plugging.
4. Test air restriction indicator for proper operation.
5. Remove and inspect primary air cleaner element; service as necessary.
6. Replace air cleaner elements at 600 hours or 12 months if no indicator.