Adjust Engine Valve Lash (Clearance)

causym 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.

Checking Valve Lash

1. Remove crankcase ventilation tube and rocker arm cover.

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. Remove plastic plugs from engine timing rotation hole (A) and timing pin hole (B).

3. Install JDE83 Flywheel Turning Tool and JDE81-4 Timing Pin.

RG7408

Flywheel Housing Timing Holes


A-Timing Rotation Hole
B-Timing Pin Hole

CED,OUO1079,450 -19-12JUL00-1/3

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

4. Rotate engine flywheel in running direction (clockwise viewed from front (A)) until timing pin locks into flywheel. Check to ensure that No. 1 cylinder is at TDC compression stroke.

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.

5. With engine lock-pinned at TDC of No. 1 piston's compression stroke (B), check valve lash on No. 1 and 3 exhaust valves (E), and No. 1 and 2 intake valves (I) to specifications. Adjust lash for these valves, if necessary. (See Adjusting Valve Lash procedure.)

Specification

Intake Valve
Rocker Arm-to-Valve Tip
Checking -Lash 		0.31-0.38 mm
(0.012-0.015 in.)
(Engine Cold)
Exhaust Valve
Rocker Arm-to-Valve Tip
Checking -Lash 		0.41-0.48 mm
(0.016-0.019 in.)
(Engine Cold)

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

7. Check valve lash on No. 2 and 4 exhaust valves (E), and No. 3 and 4 intake valves (I) to same specifications. Adjust lash for these valves, if necessary. (See Adjusting Valve Lash procedure.)

8. Replace rocker arm cover and crankcase vent tube, and install all components removed.

RG4776

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

CED,OUO1079,450 -19-12JUL00-2/3

Adjusting Valve Lash

1. Check valve lash. (See Checking Valve Lash procedure.)

2. Loosen the jam nut (A) on rocker arm adjusting screw.

3. Turn adjusting screw until valve lash is at specification. Feeler gauge should slip between rocker arm and valve tip with a slight drag.

Specification

Intake Valve
Rocker Arm-to-Valve Tip
Adjustment -Lash 		0.36 mm (0.014 in.)
(Engine Cold)
Exhaust Valve
Rocker Arm-to-Valve Tip
Adjustment -Lash 		0.46 mm (0.018 in.)
(Engine Cold)

4. Hold adjusting screw with screwdriver to prevent it from turning, and tighten jam nut to specification.

Specification

Rocker Arm Adjusting Screw Jam Nut -Torque 27 N·m (20 lb-ft)

5. Recheck valve lash. Repeat steps 1-4, if needed, until valve lash is correct.

RG7409

Adjusting Valves


A-Adjusting Screw Jam Nut

CED,OUO1079,450 -19-12JUL00-3/3