Valve Clearance: Adjustments

NOTE: To obtain accurate readings, valve lash measurements AND adjustments should only be performed when the engine coolant temperature is less than 60° C (140° F).

The 24-valve overhead system is a "low-maintenance" design. Routine adjustments are no longer necessary, however, measurement should still take place when trouble-shooting performance problems, or upon completion of a repair that includes Removal and Installation of the valve train components.

1. Disconnect battery negative cables.





2. Remove cylinder head cover (Fig. 12).





3. Remove the fuel pump gear access cover (Fig. 13).





4. Using the crankshaft barring tool #7471B, rotate the engine and align the pump gear mark with the top dead center (TDC) mark on the gear housing cover (Fig. 14).

5. With the engine in this position (pump gear mark at 12 o'clock), valve lash can be measured at the following rocker arms:
- INTAKE 1-2-4
- EXHAUST 1-3-5

Fig. 15:

Valve Lash Limit Chart:

Measure the valve lash by inserting a feeler gauge between the rocker arm socket and crosshead (Fig. 15). Refer to the Valve Lash Limit Chart for the correct specifications.
- If the measurement falls within the limits, adjustment/resetting is not necessary. Engine operation within these ranges has no adverse affect on performance, emissions, fuel economy or level of engine noise.
- If measurement falls the lash outside of the limits, adjustment/resetting is required.

6. If adjustment/resetting is required, loosen the lock nut on rocker arms and turn the adjusting screw until the desired lash is obtained:

INTAKE: 0.264 mm (0.010 in.)
EXHAUST: 0.508 mm (0.020 in.)

6. Tighten the lock nut to 24 Nm (18 ft. lbs.) and re-check the valve lash.

7. Using the crankshaft barring tool, rotate the crankshaft one revolution (360°) to align the pump gear mark to the 6 o'clock position in relation to the TDC mark on the gear housing cover (Fig. 14).
8. With the engine in this position (pump gear mark at 6 o'clock), valve lash can be measured at the remaining rocker arms:
- INTAKE 3-5-6
- EXHAUST 2-4-6

Use the same method as above for determining whether adjustment is necessary, and adjust those that are found to be outside of the limits.
9. Install the cylinder head cover (Fig. 12).
10. Install the fuel pump gear access cover.
11. Connect the battery negative cables.