Valve Clearance Adjustment - Isuzu 4JA1 Workshop Manual

VALVE CLEARANCE ADJUSTMENT

1. Bring the piston in either the No. 1 cylinder or the No. 4
cylinder to TDC on the compression stroke by turning
the crankshaft until the crankshaft damper pulley TDC
line is aligned with the timing pointer.
2. Check the rocker arm shaft bracket nuts for
looseness.
Tighten any loose rocker arm shaft bracket nuts
before adjusting the valve clearance.
Rocker Arm Shaft Bracket Nut Torque
014RY00014
8. Check for play in the No. 1 intake and exhaust valve
push rods.
If the No. 1 cylinder intake and exhaust valve push
rods have play, the No. 1 piston is at TDC on the
compression stroke.
If the No. 1 cylinder intake and exhaust valve push
rods are depressed, the No. 4 piston is at TDC on the
compression stroke.
014RY00015
Adjust the No.1 or the No. 4 cylinder valve clearances
while their respective cylinders are at TDC on the
compression stroke.
Valve Clearance (At Cold)
9. Loosen each valve clearance adjusting screw as
shown in the illustration.
10. Insert a feeler gauge of the appropriate thickness
between the rocker arm and the valve stem end.
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11. Turn the valve clearance adjusting screw until a slight
drag can be felt on the feeler gauge.
12. Tighten the lock nut securely.
13. Rotate the crankshaft 360°.
14. Realign the crankshaft damper pulley TDC notched
line with the timing pointer.
15. Adjust the clearances for the remaining valves as
shown in the illustration.
014RY00017
ENGINE MECHANICAL 6A – 31
N·m (kg·m /lb·ft)
54 (5.5/40)
0.4 (0.016)
mm (in)