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Home›Repair guides›John Deere›Check and Adjust Valve Clearance

John Deere — Check and Adjust Valve Clearance

Adjustments · Valve train / rocker arms

From a John Deere owner's manual covering: 4045TF120, 6068HF158, 6068TF120, 6068TF250. Check it applies to your exact model before use.

Applies to: John Deere 4045TF120, John Deere 6068TF120, John Deere 6068TF250

Before you start

  • To prevent accidental starting of engine while performing valve adjustments, always disconnect NEGATIVE (—) battery terminal.
  • Valve clearance MUST BE checked and adjusted with engine COLD.

Procedure

  1. Remove rocker arm cover and crankcase ventilator tube.
  2. Remove plastic plugs or cover plate from engine timing/rotation hole and timing pin hole.
  3. Using JDE83 or JD81-1 Flywheel Turning Tool, rotate engine flywheel in running direction until No. 1 cylinder is at TDC compression stroke.
  4. Insert JDG1571 or JDE81-4 Timing Pin in flywheel.
  5. With engine lock-pinned at TDC of No. 1 piston's compression stroke, check valve clearance to specifications.
  6. If valves need adjusting, loosen the jam nut on rocker arm adjusting screw.
  7. Turn adjusting screw until feeler gauge slips with a slight drag.
  8. Hold the adjusting screw from turning with screwdriver and tighten jam nut to specifications.
  9. Recheck clearance again after tightening jam nut. Readjust as necessary.
  10. Replace rocker arm cover and crankcase ventilator tube.

Tools required

Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.

Specs & values

  • Intake Valve Clearance For Checking (engine cold) 0.31—0.38 mm (0.012—0.015 in.)
  • Exhaust Valve Clearance For Checking (engine cold) 0.41—0.48 mm (0.016—0.019 in.)
  • Intake Valve Clearance For Adjusting (engine cold) 0.36 mm (0.014 in.)
  • Exhaust Valve Clearance For Adjusting (engine cold) 0.46 mm (0.018 in.)
  • Rocker Arm Adjusting Screw Jam Nut—Torque 27 N·m (20 lb-ft)
  • 4-Cylinder FridayParts $14.48 firing order 1-3-4-2; 6-Cylinder FridayParts $54.99 firing order 1-5-3-6-2-4

Full service-parts list: John Deere 6068TF250 →

Source: John Deere owner'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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