Valve Clearance: Testing and Inspection
CAMSHAFT VALVE CLEARANCEInspection and Adjustment
INSPECTION
Perform inspection as follows after removal, installation or replacement of camshaft or valve-related parts, or if there is unusual engine conditions regarding valve clearance.
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 stating, idling or causing noise), perform inspection as follows:
1. Remove rocker covers (right and left bank).
2. Measure the valve clearance as follows:
a. Set No. 1 cylinder at TDC of its compression stroke.
^ Rotate crankshaft pulley clockwise to align timing mark (grooved line without color) with timing indicator.
<-: Timing mark (grooved line without color)
^ Make sure that intake and exhaust cam nose on No. 1 cylinder (engine front side of right bank) are located as shown in the figure.
^ If not, turn crankshaft one revolution (360°) and align as shown in the figure.
b. Use a feeler gauge, measure the clearance between valve lifter and camshaft.
^ By referring to the figure, measure the valve clearances at locations marked "x" as shown in the table (locations indicated in the figure).
^ No. 1 cylinder at compression TDC
c. Rotate crankshaft by 240 degrees clockwise (when viewed from engine front) to align No. 3 cylinder at TDC its compression stroke.
NOTE: To align cylinder No. 3 with the compression top dead center, place matching marks (A) on the crankshaft pulley (1) side and on the cylinder block side at a point 240° (b) counterclockwise from the compression top dead center using the hex head of the crankshaft pulley bolt as a guide.
^ By referring to the figure, measure the valve clearances at locations marked "x" as shown in the table (locations indicated in the figure).
^ No. 3 cylinder at compression TDC
d. Rotate crankshaft by 240° clockwise (when viewed from engine front) to align No. 5 cylinder at TDC of compression stroke.
NOTE: To align cylinder No. 5 with the compression top dead center, place matching marks (A) on the crankshaft pulley (1) side and on the cylinder block side at a point 240° counterclockwise from the compression top dead center using the hex head of the crankshaft pulley bolt as a guide.
^ By referring to the figure, measure the valve clearances at locations marked "x" as shown in the table (locations indicated in the figure).
^ No. 5 cylinder at compression TDC
3. Perform adjustment if the measured value is out of the standard.
ADJUSTMENT
^ Perform adjustment depending on selected head thickness of valve lifter.
1. Measure the valve clearance.
2. Remove camshaft.
3. Remove valve lifters at the locations that are out of the standard.
4. Measure the center thickness of the removed valve lifters with a micrometer (A).
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)
^ Thickness of new valve lifter can be identified by stamp marks on the reverse side (inside the cylinder).
Stamp mark 788T indicates 7.88 mm (0.3102 in) in thickness.
A: Stamp
B: thickness of valve lifter
Available thickness of valve lifter: 27 sizes with range 7.88 to 8.40 mm (0.3102 to 0.3307 in) in steps of 0.02 mm (0.0008 in) (when manufactured at factory).
6. Install selected valve lifter.
7. Install camshaft.
8. Manually turn crankshaft pulley a few turns.
9. Make sure that the valve clearances for cold engine are within the specifications by referring to the specified values.
10. Install all removal parts in the reverse order of removal.
11. Warm up the engine, and check for unusual noise and vibration.