Checking and Adjusting Engine Valve Clearance (Except 6068SFM75 and 6068AFM75)

CAUTION: To prevent accidental starting of engine while performing valve adjustments, always disconnect NEGATIVE (–) battery terminal.

IMPORTANT: Engine valve clearance MUST BE checked and adjusted with engine COLD.

NOTE: If desired, have your authorized servicing dealer or engine distributor adjust the engine valve clearance.

1. Remove rocker arm cover and crankcase ventilator tube.

   IMPORTANT: Visually inspect contact surfaces of valve tips and rocker arm wear pads. Check all parts for excessive wear, breakage, or cracks. Replace parts that show visible damage.

   Rocker arms that exhibit excessive valve clearance should be inspected more thoroughly to identify damaged parts.

2. 
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   Flywheel Housing Timing Holes

   A - Timing Holes

   Remove plastic plugs or cover plate from flywheel housing timing holes (A).

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3. Using either JDG820 or JDE83 Flywheel Turning Tool and JDE81-4 or JDG1571 Timing Pin, rotate engine in running direction (clockwise viewed from front) until Number 1 (front) cylinder is at Top Dead Center (TDC) Compression stroke. Insert JDE81-4 or JDG1571 timing pin in flywheel.

   If Number 1 cylinder rocker arms are loose, the engine is at Number 1 "TDC Compression".

   If No. 1 cylinder rocker arms are not loose, rotate engine one full revolution (360°) to Number 1 "TDC Compression".

4. 
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   Adjust Valves

   A - Locknut

   With engine lock-pinned at “TDC” of Number 1 piston’s compression stroke, check valve clearance to following specifications, as directed in the procedures (following page) for 4 or 6-cylinder engines. If valves need adjusting, loosen the locknut (A) on rocker arm adjusting screw. Turn adjusting screw until feeler gauge slips with a slight drag. Hold the adjusting screw from turning with screwdriver and tighten locknut to 27 N˙m (20 lb-ft). Recheck clearance again after tightening locknut. Readjust clearance as necessary.

   Item	Measurement	Specification
   Intake Valve Clearance Adjustment (Rocker Arm-to-Valve Tip) (Engine Cold)	Clearance	0.35 mm (0.014 in.)
   Exhaust Valve Clearance Adjustment (Rocker Arm-to-Valve Tip) (Engine Cold)	Clearance	0.45 mm (0.018 in.)

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5. Replace rocker arm cover and crankcase ventilator tube.

4-Cylinder Engine

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4-Cylinder Engine Valve Adjustment

A - Front of Engine

B - No. 1 Piston at TDC Compression Stroke

C - No. 4 Piston at TDC Compression Stroke

E - Exhaust Valve

I - Intake Valve

NOTE: Firing order is 1-3-4-2.

Lock No. 1 piston at TDC compression stroke (B).

Adjust valve clearance on No. 1 and 3 exhaust valves and No. 1 and 2 intake valves.

Rotate flywheel 360°. Lock No. 4 piston at TDC compression stroke (C).

Adjust valve clearance on No. 2 and 4 exhaust valves and No. 3 and 4 intake valves.

6-Cylinder Engine

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6-Cylinder Engine Valve Adjustment

A - Front of Engine

B - No. 1 Piston at TDC Compression Stroke

C - No. 6 Piston at TDC Compression Stroke

E - Exhaust Valve

I - Intake Valve

NOTE: Firing order is 1-5-3-6-2-4.

Lock No. 1 piston at TDC compression stroke (B).

Adjust valve clearance on No. 1, 3, and 5 exhaust valves and No. 1, 2, and 4 intake valves.

Rotate flywheel 360°. Lock No. 6 piston at TDC compression stroke (C).

Adjust valve clearance on No. 2, 4, and 6 exhaust valves and No. 3, 5, and 6 intake valves.