To check and adjust the valve clearance of the G4GC engine, you must:
1. Remove the engine cover.
Note. Checking and adjusting the valve clearance is carried out on a cold engine (engine temperature 20°C) with the cylinder head installed.
2. Loosen the mounting bolts and remove the top cover of the drive belt.
3. Disconnect the high voltage wires from the spark plugs.
Note. When disconnecting the high voltage wires from the spark plugs, do not pull on the wires or bend them, as this may damage the wires.
4. Disconnect the recirculation hose (A) exhaust and breather hose (B) from the cylinder head cover.
5. Disconnect the throttle cable (A) from the cylinder head cover.
6. Unscrew the fastening bolts (IN) and remove the cylinder head cover.
7. Set the piston of the first cylinder to the top dead center position. To do this, turn the crankshaft pulley and align the recess on the pulley with the mark «T» on the bottom drive belt cover as shown.
8. Make sure that the hole on the camshaft gear matches the alignment mark on the bearing cap. If the hole does not match the alignment mark, turn the crankshaft one full turn (360°).
9. Check the valve clearances marked in the figure (position of the piston of the first cylinder at top dead center). Using a feeler gauge, check the clearance between the cams and the valve lifters. Write down the clearances, they will be needed later for the selection of valve shims.
Note.
Valve clearances (at engine temperature 20C):
- Inlet: 0.20mm
- Graduation: 0.28mm
Maximum allowable valve clearances:
- Intake: 0.12-0.28mm
- Graduation: 0.20-0.38mm
10. Turn the crankshaft one turn and again align the recess on the crankshaft pulley with the mark «T» on the bottom cover of the drive belt.
11. To check up size of backlashes of the valves specified in drawing.
12. Adjust the gaps of the intake and exhaust valves. To do this, turn the crankshaft so that the protruding part of the cam, the gap of which must be adjusted, is directed upwards (see picture).
13. Using a special tool (09220-2D008), press down on the valve thrust washer and place a stop between the valve thrust washer and the camshaft. Then remove the fixture.
14. Using a screwdriver (A) and magnet (IN) remove the adjusting washer.
15. Measure the thickness of the removed shim with a micrometer.
16. Calculate the thickness of the new shim so that the valve clearance matches the nominal value.
- T is the thickness of the removed shim.
- A is the measured clearance.
- N is the thickness of the new shim.
- Inlet valve: N=T+ (A-0.20mm)
- Exhaust valve: N=T+ (A-0.28mm)
17. Select a new shim, the thickness of which is closest to the calculated value.
Note. The shim range is available in twenty sizes from 2.00mm to 2.76mm in 0.04mm increments.
18. Install a new shim in the valve lifter.
19. Using a special tool (09220-2D008), press down the valve lifter and remove the stopper between the thrust washer and the camshaft.
20. Recheck valve clearance.
Thickness of new shims
Note. Thickness of new shims (in mm) stamped on their front.