Valve Clearance: Service and Repair
Camshaft 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) Remove the engine room cover. Refer to [Engine Room Cover: Removal and Installation] Service and Repair.
2) Remove the air cleaner and air duct assembly. Refer to [Air Cleaner and Air Duct: Removal and Installation] Removal and Installation.
3) Remove rocker covers (RH and LH banks). Refer to [Rocker Cover: Removal and Installation] Removal and Installation.
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°) and align as shown.
b) Use feeler gauge, measure the clearance between valve lifter and camshaft.
Valve Clearance
Unit: mm (in)
1: Approximately 20 °C (68 °F)
2: Approximately 80 °C (176 °F)
- 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° 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. Refer to [Camshaft: Removal and Installation] 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 micrometer.
5) Use the equation below to calculate valve lifter thickness for replacement.
- 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). Refer to [Service Data and Specifications] [1][2]Specifications.
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). Refer to [Service Data and Specifications] [1][2]Specifications.
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. Refer to [Camshaft: Removal and Installation] Removal and Installation.
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.