Check and Adjust Valve Clearance

RG7408-UN-06AUG96

Flywheel Housing Timing Holes

A - Timing/Rotation Hole

B - Timing Pin Hole

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

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

1. Remove rocker arm cover and crankcase ventilator tube.

2. 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.

   Remove plastic plugs or cover plate from engine timing/rotation hole (A) and timing pin hole (B).

3. NOTE: Some engines are equipped with flywheel housings which do not allow use of an engine flywheel rotation tool. These engines may be rotated from front nose of engine, using JDG966 Crankshaft Front/Rear Rotation Adapter.

   Using JDE83 or JD81-1 Flywheel Turning Tool, rotate engine flywheel in running direction (clockwise viewed from front) until No. 1 cylinder is at TDC compression stroke. Insert JDG1571 or JDE81-4 Timing Pin in flywheel.

   If No.1 cylinder rocker arms are loose, the engine is at No. 1 TDC compression.

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

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4. With engine lock-pinned at TDC of No. 1 piston's compression stroke, check valve clearance to following specifications. (Use sequence for 4-cylinder or 6-cylinder engines as outlined on next page.)

   Item	Measurement	Specification
   Intake Valve Clearance For Checking (Rocker Arm-to-Valve Tip) (Engine Cold)	Clearance	0.31—0.38 mm (0.012—0.015 in.)
   Exhaust Valve Clearance For Checking (Rocker Arm-to-Valve Tip) (Engine Cold)	Clearance	0.41—0.48 mm (0.016—0.019 in.)

5. 
   RG7409-UN-06AUG96

   Adjusting Valves

   A - Adjusting Screw Jam Nut

   If valves need adjusting, use the appropriate valve clearance adjustment procedure on the next page and adjust to specifications below. Loosen the jam nut (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 jam nut to specifications. Recheck clearance again after tightening jam nut. Readjust clearance as necessary.

   Item	Measurement	Specification
   Intake Valve Clearance For Adjusting (Rocker Arm-to-Valve Tip) (Engine Cold)	Clearance	0.36 mm (0.014 in.)
   Exhaust Valve Clearance For Adjusting (Rocker Arm-to-Valve Tip) (Engine Cold)	Clearance	0.46 mm (0.018 in.)
   Rocker Arm Adjusting Screw Jam Nut	Torque	27 N˙m (20 lb-ft)

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6. Replace rocker arm cover and crankcase ventilator tube.

4-Cylinder Engine:

RG4776-UN-31OCT97

4-Cylinder Engine Valve Adjustment

A - Front of Engine

B - No. 1 Piston TDC Compression

C - No. 4 Piston TDC Compression

E - Exhaust Valve

I - Intake Valve

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

1. Using JDE81-4 Timing Pin, lock No. 1 piston at TDC compression stroke (B).

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

3. Turn crankshaft 360°. Lock No. 4 piston at TDC compression stroke (C).

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

6-Cylinder Engine:

RG4777-UN-31OCT97

6-Cylinder Engine Valve Adjustment

A - Front of Engine

B - No. 1 Piston TDC Compression

C - No. 6 Piston TDC Compression

E - Exhaust Valve

I - Intake Valve

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

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

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

3. Turn crankshaft 360°. Lock No. 6 piston at TDC compression stroke (C).

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