Valve Clearance: Testing and Inspection

CAMSHAFT


Valve Clearance


INSPECTION
In cases of removing/installing or replacing camshaft and valve-related parts, or of unusual engine conditions due to changes in valve clearance (found malfunctions during starting, idling or causing noise), perform inspection as follows:
1. Remove rocker covers (right bank and left bank). Component Removal and Installation.
2. Measure the valve clearance as follows:
a. Set No. 1 cylinder at TDC of its compression stroke.





- Rotate crankshaft pulley in clockwise to align TDC identification notch (without paint mark) with timing indicator on front cover.





- Check that both intake and exhaust cam noses of No. 1 cylinder (engine front side of left bank) are located as shown in the figure.
- If not, turn crankshaft one revolution (360 degrees) and align as shown in the figure.





b. Use feeler gauge, measure the clearance between valve lifter and camshaft.










- By referring to the figure, measure the valve clearances at locations marked "�" as shown in the table below (locations indicated with black arrow in figure).

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










c. Rotate crankshaft pulley clockwise (when view from engine front) by 270 degrees from the position of No. 1 cylinder compression TDC to align No. 3 cylinder at TDC of its compression stroke.

NOTE:
Crankshaft pulley mounting bolt flange has a angle mark every
90 degrees. They can be used as a guide to rotation angle.





- By referring to the figure, measure the valve clearances at locations marked "�" as shown in the table below (locations indicated with white arrow in figure).
- No. 3 cylinder at compression TDC










d. Rotate crankshaft pulley clockwise (when view from engine front) by 90 degrees from the position of No. 3 cylinder compression TDC to align No. 6 cylinder at TDC of its compression stroke.





- By referring to the figure, measure the valve clearances at locations marked "�" as shown in the table below.
- No. 6 cylinder at compression TDC





3. Perform adjustment if the measured value is out of the standard. Refer to "ADJUSTMENT".

ADJUSTMENT
Perform adjustment depending on selected head thickness of valve lifter.
1. Measure the valve clearance. Testing and Inspection.
2. Remove camshaft. Removal and Installation.
3. Remove valve lifters at the locations that are out of the standard.





4. Measure the center thickness of removed valve lifters with a micrometer.
5. Use the equation below to calculate valve lifter thickness for replacement.

Valve lifter thickness calculation: t = t1 + (C1 - C2)
t = Valve lifter thickness to be replaced
t1 = Removed valve lifter thickness
C1 = Measured valve clearance
C2 = Standard valve clearance:
Intake: 0.30 mm (0.012 in)*
Exhaust: 0.33 mm (0.013 in)*
*: Approximately 20°C (68°F)





- Thickness of new valve lifter can be identified by stamp marks on the reverse side (inside the cylinder).
Stamp mark 788 indicates 7.88 mm (0.3102 in) in thickness.





6. Install selected valve lifter.
7. Install camshaft. Removal and Installation.
8. Manually turn crankshaft pulley a few turns.
9. Check that the valve clearances for cold engine are within the specifications by referring to the specified values. Testing and Inspection.
10. Install all removal parts in the reverse order of removal. Removal and Installation.
11. Warm up the engine, and check for unusual noise and vibration.