Cylinder Head - Overhaul
Cylinder Head - Overhaul
Service Repair No - 12.29.19.01
Disassembly
1. Remove cylinder head gasket.
2. Loosen screw on tool LRT-12-034.
3. Fit tool LRT-12-034 to valve and tighten screw to compress valve spring sufficiently to release collets from valve spring cap.
4. Remove 2 collets and release valve spring compressor.
5. Remove valve spring cap and valve spring.
6. Remove valve from cylinder head.
7. Remove and discard valve stem oil seal.
8. Repeat above operations for remaining valves.
9. Keep valves, springs, caps and collets in their fitted order.
Inspect
1. Clean mating faces of cylinder block and head using suitable gasket removal spray and a plastic scraper, ensure that bolt holes in block are clean and dry.
CAUTION: Do not use a metal scraper on machined surfaces may be damaged.
2. Check head and block faces for warping and pitting. Maximum warp = 0.05 mm (0.002 in.).
3. Check cylinder head height at each end of head. Renew a head which is outside limits a 22.94 mm (0.903 in.) - New b 62.56 mm (2.463 in.) - New
4. Cylinder head can be refaced to 0.50 mm (0.02 in.) max. below head height.
5. Remove carbon deposits from exhaust valve guide using a 8.70 mm (0.34 in.) diameter reamer inserted from combustion face side of cylinder head.
6. Clean cylinder head, valve springs, valves and inlet valve guide bores. Ensure all loose particles of carbon are removed on completion.
7. Check the following valve dimensions. Renew valves as necessary.
^ Valve head diameter's': Inlet = 39.75 to 40.00 mm (1.56 to 1.57 in.).
^ Valve head diameter's': Exhaust = 34.23 to 34.48 mm (1.35 to 1.36 in.). Valve stem diameter 'B': Inlet = 8.664 to 8.679 mm (0.341 to 0.342 in.).
^ Valve stem diameter 'B': Exhaust = 8.651 to 8.666 mm (0.340 to 0.341 in.).
8. Check installed height of valve.
^ Valve installed height 'C'= 47.63 mm (1.875 in.).
9. Check condition of valve springs. Valve springs must be replaced as a complete set.
^ Valve spring free length = 48.30 mm (1.90 in.).
^ Valve spring fitted length = 40.40 mm (1.59 in.).
^ Spring load - valve closed = 339 + 10 N (76 + 2.25 lbs).
^ Spring load - valve open = 736 + 10 N (166 + 2.25 lbs).
10. Check valve stem to guide clearance using a new valve. Renew valve guides as necessary.
^ Valve stem to guide clearance 'D': Inlet = 0.025 to 0.066 mm (0.001 to 0.002 in.).
^ Valve stem to guide clearance 'D': Exhaust = 0.038 to 0.078 mm (0.0015 to 0.003 in.).
11. Using valve guide remover tool LRT-12-037 press valve guide into combustion face side of cylinder head.
12. Lubricate new valve guide with engine oil and partially fit to cylinder head, from valve spring side of head, using tool LRT-12-039A. Service valve guides are 0.025 mm (0.001 in.) oversize on outside diameter to ensure an interference fit.
13. Fully fit guide using tool LRT-12-039A and distance piece tool LRT-12-519.
^ Valve guide installed height 'A' = 15.00 mm (0.590 in.).
14. Ream valve guide to 8.70 mm (0.342 in.).
15. Position cylinder head stands and mount cylinder head on stands.
16. Check valve seat insert for pitting, burning, cracks and wear. Replace as necessary. Service valve seat inserts are available 0.025 mm (0.001 in.) oversize on outside diameter to ensure interference fit.
17. Remove worn valve seat.
CAUTION: Take care not to damage the counterbore in the cylinder head when removing the valve seats.
18. Heat cylinder head evenly to approximately 120° (250°F).
WARNING: Handle the hot cylinder bead with care.
19. Using a suitable mandrel, press new insert fully into counterbore.
20. Allow cylinder head to air cool.
21. Recut valve seat in head and lap in valves using fine paste.
22. Coat valve with a small quantity of engineer's blue, insert valve and press into position several times without rotating. Seating position should be in center of valve face.
23. Check valve installed height if valve seats have been refaced or renewed.
^ Valve installed height= 47.63 mm (1.875 in.).
24. Reface valves as necessary. If a valve has to be ground to a knife-edge to obtain a true seat, renew valve.
25. Cut valve seats using tools LRT-12-501, LRT 12-503 and LRT-12-517.
^ Valve seat angle 'A' = 45°.
^ Valve seat width 'A' Inlet = 36.83 mm (1.45 in.).
^ Valve seat width 'A' Exhaust = 31.50 mm (1.24 in.).
^ Width IB' - Inlet = 0.89 to 1.4 mm (0.035 to 0 055 in.)
^ Width 'B' - Exhaust = 1.32 to 1.83 mm (0.052 to 0.072 in.).
^ Angle 'C' = 56° to 57°.
^ Angle 'D' = 46° to 46° 25'.
^ Angle 'E' = 20°.
26. Ensure cutter blades are correctly fitted to cutter head with angled end of blade downwards, as illustrated. Check that cutter blades are adjusted so that middle of blade contacts area of material to be cut. Use light pressure and only remove the minimum of material necessary.
27. Clean valve seat and valve.
Reassembly
1. Clean spring caps, collets and valve springs.
2. Lubricate new valve stem oil seal with clean engine oil and fit seal.
3. Lubricate valve with clean engine oil and fit valve.
4. Fit spring and cap, compress spring using tool LRT-12-034 and fit collets.
5. Release valve spring and remove tool LRT-12034.
6. Fit cylinder head gasket.