Valve Clearance: Adjustments

Valve Clearance Inspection And Adjustment

NOTE:
Inspect and adjust the valve clearance when the engine is cold (Engine coolant temperature : 20°C±5°C(59 - 77°F)) and cylinder head is installed on the cylinder block.

1. Remove the engine cover.
2. Remove air cleaner assembly.
3. Remove the surge tank.
4. Remove the cylinder head cover.
(1) Disconnect the ignition coil connector and remove the ignition coil.
(2) Remove the cylinder head cover.




5. Set the piston of the No.1 cylinder to TDC(Top Dead Center) position.
(1) Turn the crankshaft pulley clockwise and align its groove with the timing mark "T" of the timing chain cover.
(2) Check that the timing marks of the camshaft sprocket are in straight line on that of the cylinder head cover surface as shown in the illustration. It makes the piston of the No.1 cylinder position at TDC.





NOTE:
If not, turn the crankshaft one revolution clockwise.

6. Inspect the intake and the exhaust valve clearance.
(1) With the piston of the No.1 cylinder positioning at TDC, the valves which can be measured its clearance are as shown below.




Measurement method.
A. Using a thickness gauge, measure the clearance between the tappet and the base circle of camshaft.
B. Record the out-of-specification valve clearance measurements. They will be used later to determine the required adjusting tappet for replacement.

Specification
Limit (Engine coolant temperature : 20°C [68°F])
Intake : 0.10 - 0.30mm (0.0039 - 0.0118in.)
Exhaust : 0.20 - 0.40mm (0.0079 - 0.0157in.)


(2) Turn the crankshaft pulley one revolution (360°) clockwise and align the groove with the timing mark "T" of the timing chain cover.
(3) With the piston of the No.4 cylinder positioning at TDC, the valves which can be measured its clearance are as shown below.




7. Adjust the intake and the exhaust valve clearances.
(1) Set the piston of the No.1 cylinder to the TDC/position.
(2) Remove the timing belt.
(3) Remove the camshaft bearing caps(A, B).




(4) Remove the camshaft assembly.
(5) Remove MLA(Mechanical Lash Adjuster)s.
(6) Measure the thickness of the removed tappet using a micrometer.




(7) Calculate the thickness of a new tappet so that the valve clearance comes within the specified value.

T : Thickness of removed tappet
A : Measured valve clearance
N : Thickness of new tappet
Intake : N = T + [A - 0.20mm(0.0079in.)]
Exhaust : N = T + [A - 0.25mm (0.0098in.)]


(8) Select a new tappet with a thickness as close as possible to the calculated value.

NOTE:
Tappets are available with 41different size increments of 0.015mm (0.0006in.) from 3.00mm (0.118in.) to 3.600mm (0.1417in.)

(9) Place a new tappet on the cylinder head.

NOTE:
Apply engine oil on the periphery surface of the selected tappet.

(10) Install the intake and exhaust camshafts.
(11) Install the bearing caps.
(12) Install the timing belt.
(13) Turn the crankshaft two revolutions in the operating direction(clockwise) and realign crankshaft sprocket and camshaft sprocket timing marks(A).
(14) Recheck the valve clearance.

Specification (Engine coolant temperature: 20°C[68°F])
Intake : 0.17 - 0.23mm (0.0067 - 0.0090in.)
Exhaust : 0.27 - 0.33mm (0.0106 - 0.0129in.)