John Deere — Flush Cooling System and Replace Thermostats

Maintenance

From a John Deere operator's manual covering: 4039, 4045, 6059, 6068, RG4697. Check it applies to your exact model before use.

Applies to: John Deere 4039, John Deere 4045, John Deere 6059, John Deere 6068

Procedure

1. Slowly open the cooling system filler cap or radiator cap to relieve pressure.
2. Open radiator drain valve. Drain all coolant from radiator.
3. On left side of engine, open drain valve or remove drain plug from engine block. Drain all coolant from engine block.
4. Close all drain valves after coolant has drained.
5. Fill the cooling system with clean water. Run the engine about 10 minutes to stir up possible rust or sediment.
6. Stop engine and immediately drain the water before rust and sediment settle.
7. Fill the cooling system with clean water and TY15979 John Deere Heavy Duty Cooling System Cleaner or equivalent cleaner.
8. Fill with water to flush the system. Run engine about 10 minutes, then drain flushing water.
9. For thermostat replacement, remove cap screws and thermostat cover.
10. Remove and discard thermostats and all gasket material.
11. Install new gasket, new thermostats and cover. Tighten all cap screws to 27 N-m (20 lb-ft).
12. Add coolant to radiator until coolant touches bottom of filler neck.
13. Run engine until it reaches operating temperature; normal coolant temperature range is 82-94 C (180-202 F).
14. After running engine, check coolant level and entire cooling system for leaks.

Full service-parts list: John Deere 4039 →, John Deere 4045 →, John Deere 6068 →

Source: John Deere operator's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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