John Deere Powertech Tier II 6068 Engine

⚠ Disconnect negative battery terminal before valve adjustments to prevent accidental starting.

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

Tools: JDE 820 or JDE 83 Flywheel Turning Tool, JDE 81-4 Timing Pin, Feeler gauge, Screwdriver, Torque wrench

1. Disconnect negative battery terminal before valve adjustment.
2. Remove rocker arm cover with ventilator tube.
3. Remove plastic plugs or cover plate in engine timing holes on front side of flywheel.
4. Rotate flywheel clockwise with flywheel turning tool until timing pin engages timing hole.
5. Both rocker arms for No. 1 cylinder will be loose at TDC.
6. If not, rotate flywheel one complete turn and reinstall timing pin.
7. Adjust intake valve clearance to 0.36 mm (0.014 in) and exhaust to 0.46 mm (0.018 in).
8. Loosen jam nut, turn adjusting screw until slight drag on feeler gauge.
9. Hold adjusting screw and tighten jam nut to 27 N·m (20 lb-ft).
10. Check clearance again after tightening jam nut.
11. For 4-cylinder, adjust No. 1 and No. 3 exhaust and No. 1 and No. 2 intake; rotate 360° and adjust No. 2 and No. 4 exhaust and No. 3 and No. 4 intake.
12. For 6-cylinder, adjust No. 1, No. 3, No. 5 exhaust and No. 1, No. 2, No. 4 intake; rotate 360° and adjust No. 2, No. 4, No. 6 exhaust and No. 3, No. 5, No. 6 intake.

⚠ Do not run engine with air cleaner removed.

1. Inspect air cleaner every 100 hours.
2. Replace filter every 500 hours or yearly, whichever comes first.
3. Clean rubber tube at cleaner; loosen hose clamp and attaching strip.
4. Ensure rubber tube is in good condition and new filter is clean and installed properly.
5. Start engine and check for leaks.

Tools: Hydrometer

1. Check electrolyte level every 50 hours or once per month; add distilled water to manufacturer's recommended level.
2. Check and clean batteries, cables, and terminals every 100 hours.
3. Clean corrosion with water and baking soda solution; flush with clean water.
4. Tighten terminals and grease them to inhibit corrosion.
5. Check battery condition with hydrometer every 500 hours.

⚠ Do not crack any fuel lines to bleed the fuel system on four-valve cylinder head engines.

1. On fuel filter base, loosen air bleed vent screw by hand two full turns.
2. Operate fuel supply pump primer lever or primer button until fuel flows out of bleed vent screw.
3. Tighten bleed vent screw securely.
4. Continue operating primer until pumping action is no longer felt.
5. If engine does not start, repeat steps 1-4.

1. Operate engine under various conditions, particularly heavy loads with minimal idling, to seat components.
2. Oil consumption is greater during break-in.
3. Change engine oil and filter at 50 hours using API CC, CD, or CE break-in oil.
4. Change oil and filter again at 100 hours.
5. Frequently check engine temperature and oil pressure gauges.

⚠ Overtightening can damage filter housing.

Tools: Filter wrench

1. Use filter wrench to remove old filter; dispose in approved manner.
2. Make sure old filter gasket is removed and discarded.
3. Lubricate rubber gasket on new filter and screw on until gasket meets sealing surface.
4. Using hands only, tighten filter one-half turn farther.
5. Fill engine with recommended oil; start and check for leakage.
6. Stop engine and check oil level; add oil if necessary.

⚠ Use extreme caution when working on hot engines to avoid burns.

1. Check coolant level each day before starting engine.
2. Remove pressure cap from expansion tank and check water level.
3. Level should be about 1 3/4 in. (4-5 cm) below filler cap sealing surface when engine is cold.
4. When filling, open venting cock on top of turbocharger to prevent air pockets.
5. Pressure valve in filler cap releases at approximately 7 PSI (0.5 bar).
6. Makeup coolant must meet engine coolant requirements.

Tools: Oil dipstick

1. Check oil level in crankcase with oil dipstick daily.
2. Oil level must be between 'waffled area' and 'oo'.
3. Never allow level to go below 'oo'.
4. Always add same viscosity oil as already in crankcase.

⚠ Perform service with engine shut down.

1. Check red filter service indicator button daily; if it pops up, change filter element.
2. After changing element, unscrew clear plastic cover on button and push indicator down to reset.
3. Replace cover.
4. Normally change filter element every 750 hours.
5. Check hoses and O-rings on crankcase vent system.

⚠ Use extreme caution when working on hot engines to avoid burns.

1. Flush cooling system and check for leaks and blockage every 2000 hours with engine stopped and cold.
2. Close seacock.
3. Remove pressure cap from expansion tank; open cooling system air vent on turbocharger if applicable.
4. Open drains on exhaust manifold and engine block; drain fresh water system.
5. For keel cooling, vessel must be out of water to drain keel cooler.
6. With drains open, pour clean water into expansion tank until water from drain is clear.
7. Close drains when flushing complete.
8. Fill fresh water system with recommended coolant mixture.
9. Close cooling system air vent on turbocharger.
10. Open seacock.
11. Start engine; check hoses and connections and repair leakage.

⚠ Relieve pressure before disconnecting fuel lines.

1. Check primary fuel filter daily; empty collection bowl as necessary.
2. Change primary element every 500 hours or whenever necessary.
3. If bowl fills with water, change primary and secondary elements immediately.
4. Change secondary fuel filter every 500 hours.

1. Drain cooling system.
2. Remove cooling water pipes between heat exchanger and water pump inlet.
3. Disconnect hose to seawater pump.
4. Unscrew attaching bolts holding heat exchanger to expansion tank.
5. Remove bolts holding heat exchanger cover.
6. Wash core inside and out; use chemical agents if necessary.
7. Clean accessible parts of heat exchanger housing.
8. Reassemble using new gaskets and sealing rings.