Valve Clearance: Service and Repair
Camshaft Valve ClearanceINSPECTION
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) Remove the engine room cover.
2) Remove the air cleaner and air duct assembly.
3) Remove rocker covers (RH and LH banks).
4) 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 (A) (grooved line without color) with timing indicator (B).
^ Make sure that intake and exhaust cam noses on No. 1 cylinder (engine front side of RH bank) are located as shown.
^ If not, rotate crankshaft one revolution (360 degrees) and align as shown.
b) Use feeler gauge, measure the clearance between valve lifter and camshaft.
Valve clearance:
^ Measure the valve clearances at locations marked "x" as shown in the table below (locations indicated in the illustration) with feeler gauge.
^ No. 1 cylinder at compression TDC
c) Rotate crankshaft by 240° clockwise (when viewed from engine front) to align No. 3 cylinder at TDC of its compression stroke.
NOTE:
Crankshaft pulley bolt flange has a stamped line every 60°. They can be used as a guide to rotation angle.
^ Measure the valve clearances at locations marked "x" as shown in the table below (locations indicated in the illustration) with feeler gauge.
^ No. 3 cylinder at compression TDC
d) Rotate crankshaft by 240° degrees clockwise (when viewed from engine front) to align No. 5 cylinder at TDC of compression stroke.
^ Measure the valve clearances at locations marked "x" as shown in the table below (locations indicated in the illustration) with feeler gauge.
^ No. 5 cylinder at compression TDC
5) For the measured value out of the standard, perform adjustment.
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 removed valve lifters with 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 degrees C (68 degrees F).
^ Thickness of new valve lifter can be identified by stamp marks on the reverse side (inside the cylinder).
Intake
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).
Exhaust
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).
CAUTION:
Install identification letter at the end and top, "U" and "N", at each of proper positions. (Be careful of mis-installation between intake and exhaust.)
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) Installation of the remaining components is in the reverse order of removal.
11) Start the engine, and check for unusual noise and vibration.