Valve Clearance: Service and Repair
CAMSHAFT VALVE CLEARANCE
Inspection and Adjustment
INSPECTION
Check valve clearance if applicable to the following cases:
Intake side:
- At the removal and installation of VVEL ladder assembly or valve-related parts, or at the occurrence of malfunction (poor starting, idle malfunction, unusual noise) due to aged deterioration in valve clearance.
CAUTION:
Valve clearance check on the intake side is not required after replacing the VVEL ladder assembly and cylinder head assembly with a new one. (Install new VVEL ladder assembly and cylinder head assembly in factory-shipped condition because it is factory-adjusted and inspected.)
NOTE:
VVEL ladder assembly cannot be replaced as a single part, because it is machined together with cylinder head assembly.
Exhaust side:
- At the removal, installation, and replacement of camshaft (EXH) or valve-related parts, or at the occurrence of malfunction (poor starting, idle malfunction, unusual noise) due to aged deterioration in valve clearance.
1. Remove rocker covers (bank 1 and bank 2). Removal And Installation.
2. Measure the valve clearance as follows:
- Use the feeler gauge (commercial service tool) of curved-tip. This allows the feeler gauge to access the clearance between camshaft and valve lifter with ease.
Valve clearance : Camshaft "Camshaft".
NOTE:
Be sure to note the following points when measuring valve clearance on the intake side.
- Before measuring, check that the position of drive shaft nose is within the angle shown in the figure.
A : Bank 1
B : Feeler gauge (commercial service tool)
D : View D
c : 45 degrees (drive shaft nose angle
White Arrow : Insertion direction of feeler gauge on the bank 1
Black Arrow : Insertion direction of feeler gauge on the bank 2
- Refer to the illustration for the insertion direction of the feeler gauge since the direction depends on the bank.
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.
Arrow : Timing mark (grooved line without color)
- Check that exhaust cam nose on No. 1 cylinder (engine front side of bank 1) is located as shown in the figure.
1 : Camshaft (EXH) (bank 1)
Arrow: Engine Front
- If not, turn crankshaft one revolution (360 degrees) and align as shown in the figure.
- By referring to the figure, measure the valve clearances at locations marked "x" as shown in the table below (locations indicated in the figure).
Arrow: Engine Front
- No. 1 cylinder at compression TDC
b. Rotate crankshaft 240 degrees clockwise (when viewed from engine front) to align No. 3 cylinder at TDC its compression stroke.
NOTE:
Mark a position 240 degrees (b) from a corner of the hexagonal part of crankshaft pulley mounting bolt as shown in the figure.
Use the hexagonal part as a guide.
1 : Crankshaft pulley
A : Paint mark
- By referring to the figure, measure the valve clearances at locations marked "x" as shown in the table below (locations indicated in the figure).
Arrow: Engine Front
- No. 3 cylinder at compression TDC
c. Rotate crankshaft 240 degrees clockwise (when viewed from engine front) to align No. 5 cylinder at TDC of compression stroke.
NOTE:
Mark a position 240 degrees (b) from a corner of the hexagonal part of crankshaft pulley mounting bolt as shown in the figure.
Use the hexagonal part as a guide.
1 : Crankshaft pulley
A : Paint mark
- By referring to the figure, measure the valve clearances at locations marked "x" as shown in the table below (locations indicated in the figure).
Arrow: Engine Front
- No. 5 cylinder at compression TDC
3. Perform adjustment or replacement if the measured value is out of the standard.
- If a valve clearance on the exhaust side is out of specification, adjust the valve clearance.
- If a valve clearance on the intake side is out of specification, replace VVEL ladder assembly and cylinder head assembly. Exploded View and Exploded View.
CAUTION:
Never adjust valve clearance on the intake side.
NOTE:
Since the valve lifter (INT) cannot be replaced by the piece, VVEL ladder assembly and cylinder head assembly replacement are required.
CAMSHAFT (EXH) VALVE CLEARANCE ADJUSTMENT
- Perform adjustment depending on selected head thickness of valve lifter (EXH).
1. Measure the valve clearance. Refer to "INSPECTION".
2. Remove VVEL ladder assembly and camshaft (EXH). Disassembly And Assembly.
CAUTION:
Never loosen adjusting bolts and mounting bolts (black color) of VVEL ladder assembly.
3. Remove valve lifter (EXH) at the locations that are out of the standard.
4. Measure the center thickness of the removed valve lifters (EXH) with a micrometer (A).
5. Use the equation below to calculate valve lifter (EXH) thickness for replacement.
Valve lifter (EXH) thickness calculation: t = t1 + (C1 - C2)
t = Valve lifter (EXH) thickness to be replaced
t1 = Removed valve lifter (EXH) thickness
C1 = Measured valve clearance
C2 = Standard valve clearance:
Exhaust : 0.33 mm (0.013 in)
C = Measured valve clearance
C = Standard valve clearance:
Exhaust : 0.33 mm (0.013 in)
- Thickness of new valve lifter (EXH) 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.
A : Stamp
B : Thickness of valve lifter (EXH)
Available thickness of valve lifter (EXH): 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). [1][2]Camshaft, Engine.
6. Install selected valve lifter (EXH).
7. Install VVEL ladder assembly and camshaft (EXH). Disassembly And Assembly.
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. SEE Inspection and Adjustment.
10. Install all removed parts in the reverse order of removal.
11. Warm up the engine, and check for unusual noise and vibration.