Valve Clearance: Adjustments
VALVE CLEARANCE INSPECTION AND ADJUSTMENTMLA (MECHANICAL LASH ADJUSTER)
NOTE: Inspect and adjust the valve clearance when the engine is cold (Engine coolant temperature: 20°C) and cylinder head is installed on the cylinder block.
1. Remove the engine cover (A).
2. Remove the cylinder head cover.
1) Disconnect the ignition coil connector (A) and re move the ignition coil.
2) Disconnect the P.C.V hose (A) and the breather hose from the cylinder head cover.
3) Loosen the cylinder head cover bolts and then remove the cover (A) and gasket.
3. Set No. 1 cylinder to TDC/compression.
1) Turn the crankshaft pulley and align its groove with the timing mark "T" of the lower timing chain cover.
2) Check that the mark (A) of the camshaft timing sprockets are in straight line on the cylinder head surface as shown in the illustration. If not, turn the crankshaft one revolution (360°).
4. Inspect the valve clearance.
1) Check only the valve indicated as shown. [No. 1 cylinder: TDC/Compression] measure the valve clearance.
^ Using a thickness gauge, measure the clearance between the tappet and the base circle of camshaft.
^ Record the out-of-specification valve clearance measurements. They will be used later to determine the required replacement adjusting tappet.
Valve clearance
Specification
Engine coolant temperature: 20°C [68°F]
Limit
Intake: 0.10 - 0.30 mm (0.0039 - 0.0118 inch)
Exhaust: 0.20 - 0.40 mm (0.0079 - 0.0157 inch)
2) Turn the crankshaft pulley one revolution (360°) and align the groove with timing mark "T" of the lower timing chain cover.
3) Check only valves indicated as shown. [NO. 4 cylinder: TDC/compression]. Measure the valve clearance.
5. Adjust the intake and exhaust valve clearance.
1) Set the No. 1 cylinder to the TDC/compression.
2) Marks on the timing chain and camshaft timing sprockets.
3) Turn the crankshaft pulley 15° clockwise.
4) Remove the service hole bolt (A) of the timing chain cover.
CAUTION: The bolt must not be reused once it has been assembled.
5) Insert a thin rod in the service hole of the timing chain cover and release the ratchet.
6) Remove the front camshaft bearing cap (A).
7) Remove the exhaust camshaft sprocket.
8) Remove the exhaust camshaft bearing cap and exhaust camshaft.
9) Remove the intake camshaft bearing cap and in take camshaft.
CAUTION: When disconnect the timing chain from the camshaft timing sprocket, hold the timing chain.
10) Secure the timing chain.
CAUTION: Be careful not to drop anything inside timing chain cover
11) Measure the thickness of the removed tappet using a micrometer.
12) Calculate the thickness of a new tappet so that the valve clearance comes within the specified value.
Valve clearance (Engine coolant temperature: 20°C)
T: Thickness of removed tappet
A: Measured valve clearance
N: Thickness of new tappet
Intake: N = T + [A - 0.20 mm (0.0079 inch)]
Exhaust: N = T + [A - 0.30 mm (0.0118 inch)]
13) Select a new tappet with a thickness as close as possible to the calculated value.
NOTE: Tappets are available in 47 size increments of 0.015 mm (0.0006 inch) from 3.00 mm (0.118 inch) to 3.690 mm (0.1452 inch)
14) Place a new tappet on the cylinder head.
15) Hold the timing chain, and install the intake camshaft and timing sprocket assembly.
16) Align the matchmarks on the timing chain and camshaft timing sprocket.
17) Install the intake and exhaust camshaft.
18) Install the front bearing cap.
19) Install the service hole bolt.
Tightening torque 12 - 15 Nm (1.2 - 1.5 kgf.m, 8.8 - 11.0 ft. lbs.)
20) Turn the crankshaft two turns in the operating direction (clockwise) and realign crankshaft sprocket and camshaft sprocket timing marks.
21) Recheck the valve clearance.
Valve clearance (Engine coolant temperature: 20°C)
[Specification]
Intake: 0.17 - 0.23 mm (0.0067 - 0.0090 inch)
Exhaust: 0.27 - 0.33 mm (0.0106 - 0.0129 inch)