Valve Clearance: Service and Repair

CAMSHAFT VALVE CLEARANCE

Valve Clearance

INSPECTION

NOTE:
Perform the following inspection after removal, installation or replacement of camshaft or valve-related parts, or if there are unusual engine conditions due to changes in valve clearance over time (starting, idling, and/or noise).
1. Warm up the engine. Then stop the engine.
2. Remove the engine room cover. Service and Repair.
3. Remove the air cleaner and air duct assembly. Removal and Installation.
4. Remove the RH bank and LH bank rocker covers using power tool. Removal and Installation.

5. Turn the crankshaft pulley in the normal direction (clockwise when viewed from engine front) to align TDC identification notch
(without paint mark) with timing indicator.

6. At this time, make sure both the intake and exhaust cam noses of No. 1 cylinder (top front on LH bank) face outside.
- If they do not face outside, turn crankshaft pulley once more.

7. Measure valve clearances at the locations marked "�" as shown in the table below (locations indicated with black arrow).
- : Engine front
- (black): Measurable at No.1 cylinder compression top dead center
- (white): Measurable at No. 3 cylinder compression top dead center
- A: RH
- B: LH
- C: Exhaust
- D: Intake

NOTE:
Firing order 1-8-7-3-6-5-4-2
- No. 1 cylinder compression TDC

- Measure valve clearance using suitable tool. Specifications.

CAUTION:
If the inspection was carried out with a cold engine, make sure the values with a fully warmed up engine are still within specifications.
8. Turn the crankshaft pulley clockwise 270� from the position of No. 1 cylinder compression TDC to obtain No. 3 cylinder compression TDC.

9. Measure valve clearances at the locations marked "�" as shown in the table below (locations indicated with white arrow).
- : Engine front
- (black): Measurable at No.1 cylinder compression top dead center
- (white): Measurable at No. 3 cylinder compression top dead center
- A: RH
- B: LH
- C: Exhaust
- D: Intake

NOTE:
Firing order 1-8-7-3-6-5-4-2
- No. 3 cylinder compression TDC

10. Turn the crankshaft pulley clockwise 90� from the position of No.
3 cylinder compression TDC (clockwise by 360� from the position of No. 1 cylinder compression TDC) to measure the intake and exhaust valve clearances of No. 6 cylinder (G) and the exhaust valve clearance of No. 2 cylinder (E).
- : Front
- A: RH
- B: LH
- C: Exhaust
- D: Intake
- E: No. 2 cylinder
- F: No. 4 cylinder
- G: No. 6 cylinder
- H: No. 8 cylinder
- J: No. 1 cylinder
- K: No. 3 cylinder
- L: No. 5 cylinder
- M: No. 7 cylinder
11. If out of specifications, adjust as necessary.

ADJUSTMENT

NOTE:
- Perform adjustment depending on the selected head thickness of the valve lifter.
- The specified valve lifter thickness is the dimension at normal temperatures. Ignore dimensional differences caused by temperature. Use the specifications for hot engine condition to adjust.
1. Remove the camshaft. Removal and Installation.
2. Remove the valve lifters at the locations that are out of specification.

3. Measure the center thickness of the removed valve lifters using suitable tool.
4. Use the equation below to calculate the valve lifter thickness for replacement.
- Valve lifter thickness calculation:
Thickness of replacement valve lifter = t1+ (C1 - C2) t1 = Thickness of removed valve lifter
C1 = Measured valve clearance
C2= Standard valve clearance:

- Thickness of a new valve lifter can be identified by stamp marks on the reverse side (inside the cylinder).
Stamp mark N788 indicates 7.88 mm (0.3102 in) in thickness.
- Available thickness of valve lifter: 25 sizes with range 7.88 to 8.36 mm (0.3102 to 0.3291 in) in steps of 0.02 mm (0.0008 in)
(when manufactured at factory). Specifications.
5. Install the selected valve lifter.
6. Install the camshaft.
7. Manually turn the crankshaft pulley a few turns.
8. Make sure the valve clearances for a cold engine are within specifications. Specifications.
9. After completing the repair, check the valve clearances again with the specifications for a warmed engine.
Make sure the values are within specifications. Specifications.