2.
Remove scale, sealing compound and carbon deposits completely. After cleaning the oil passages, apply compressed air to verify that the passagesare not clogged.
Check the cylinder head for cracks, damage and coolant leakage. If cracked, replace the cylinder head.
Remove scale, sealing compound and carbon deposits completely. After cleaning the oil passages, apply compressed air to verify that the passagesare not clogged.
Check the cylinder head surface for flatness in the direction as shown in the illustration. If flatness exceeds service limit in any direction, either replace the cylinder head or machine the cylinder head matching surface lightly.
Flatness of cylinder head gasket surface |
Standard : Less than 0.03 mm (0.0012 in.) |
Limit : 0.2 mm ( 0.008 in.) |
Using a wire brush, clean the valve thoroughly.
Check each valve for wear, damage and distortion of the head and the stem at B Position. Replace, if necessary. If stem end, A, is hollowed out or worn, resurface as necessary. This correction must be limited to a minimum.Also resurface the valve face.
Replace the valve if the margin has decreased to less than the service limit.
Margin |
[Standard] |
Intake : 1.0 mm (0.040 in.) |
Exhaust : 1.5 mm (0.059 in.) |
[Limit] |
Intake : 0.7 mm (0.028 in.) |
Exhaust : 1.0 mm (0.040 in.) |
Check the free height of each valve spring. If they exceed the service limit, replace the springs.
Using a square, test the squareness of each spring. If a spring is excessively out- of-square, replace it.
Valve spring |
[Standard] |
Free height : 45.82 mm (1.804 in.) |
Load : 25.3kg / 40 mm (55.8 lb / 1.57 in.) |
Out of square : 1.5° or less |
[Limit] |
Free height : 44.82 mm (1.7646 in.) |
Out of square : 4° |
Valve stem - to - guide clearance |
[Standard] |
Intake : 0.020 - 0.047 mm (0.0008 - 0.0020 in.) |
Exhaust : 0.050 - 0.085 mm (0.0020 - 0.0033 in.) |
[Limit] |
Intake : 0.1 mm (0.0040 in) |
Exhaust : 0.15 mm (0.0059 in.) |
Cut away the inner face of the valve seat to reduce the wall thickness.
Enlarge the diameter of the valve seat so that it matches the specified oversize hole diameter of the new valve seat ring.
Heat the cylinder head to about 250°C (480°F) and press-fit an oversize seat ring for the bore in the cylinder head.
Using lapping compound, lap the valve to the new seat.
Valve seat contact width : |
0.9 - 1.3 mm (0.035 - 0.051 in.) |
Description | Size mm (in.) | Size mark | Seat ring height H mm(in.) | Oversize hole diameter I.D. mm(in.) |
Intake valve Seat ring | 0.3(0.012) O.S. 0.6(0.024) O.S. | 30 60 | 7.9-8.1 (0.311-0.319) 8.2-8.4 (0.323-0.331) | 35.300-35.325 (1.3898-1.3907) 35.600-35.625 (1.4016-1.4026) |
Exhaust valve Seat ring | 0.3(0.012) O.S. 0.6(0.024) O.S | 30 60 | 7.9-8.1 (0.311-0.319) 8.2-8.4 (0.323-0.331) | 33.300-33.325 (1.3110-1.3120) 33.600-33.625 (1.3228-1.3238) |
Using the special tool (09222 - 21200A), withdraw the old valve guide toward the bottom of cylinder head.
Recondition the valve guide hole so that it can match the newly press-fitted oversize valve guide.
Using the special tool (09222-21200 A, B), press-fit the valve guide. The valve guide must be press-fitted from the upper side of the cylinder head. Keep in mind that the intake and exhaust valve guides are different in length.
Do not install a valve guide unless it is oversize.
After the valve guide is press-fitted, insert a new valve and check for proper stem-to-guide clearance.
After the valve guide is replaced, check that the valve is seated properly. Recondition the valve seats as necessary.
Over size mm (in.) | Size mark | Oversize valve guide hole size mm (in.) |
0.05(0.002) | 5 | 12.050 - 12.068 (0.4744 - 0.4751 ) |
0.25 (0.010) | 25 | 12.250 - 12.268 (0.4823 - 0.4830) |
0.50 (0.020) | 50 | 12.500 - 12.518 (0.4921 - 0.4928) |
