Overhaul
Cylinder Head
Cylinder Head - Remove
1. Remove rocker shaft assembly.
2. Mark heads LH and RH for reassembly.
NOTE: RH cylinder head illustrated.
3. Using sequence shown, remove and discard 10 bolts securing cylinder head to cylinder block.
4. Release cylinder head from 2 dowels and remove cylinder head.
5. Remove and discard cylinder head gasket.
6. Repeat above procedures for remaining cylinder head.
Valves And Springs - Remove
1. Remove spark plugs.
2. Using valve spring compressor LRT-12-034 or a suitable alternative, compress valve spring.
3. Compress valve spring sufficiently to release collets from valve spring cap.
4. Release spring compressor and remove collets, valve, valve spring cap and valve spring.
5. Repeat above operations for remaining valves.
NOTE: Keep valves, springs, caps and collets in fitted order.
6. Remove and discard valve stem oil seals.
Cylinder Head - Inspection
1. Clean all traces of gasket material from cylinder head using a plastic scraper.
2. Check core plugs for signs of leakage and corrosion, replace as necessary. Apply Loctite 572 to threads of screwed core plugs.
3. Check gasket face of each cylinder head for warping, across centre and from corner to corner.
Maximum warp = 0.05 mm (0.002 in)
4. Check cylinder head height at each end of cylinder head:
A = 22.94 mm (0.903 in) - New
B = 62.56 mm (2.463 in) - New
5. Cylinder heads may be refaced:
Reface limit = 0.50 mm (0.02 in) from new dimension
Valves, Valve Springs And Guides - Inspection
NOTE: Two types of exhaust valve may be fitted - standard valves A in illustration or carbon break valves - B in illustration. Carbon break valves may be identified by the machined profile C on the valve stem. To prevent exhaust valves sticking, standard exhaust valves should be replaced with carbon break valves during engine overhaul.
1. Remove carbon deposits from valve guides using an 8.70 mm (0.34 in) diameter reamer inserted from combustion face side of cylinder head.
2. Clean valve springs, cotters, caps and valves. Clean inlet valve guide bores. Ensure all loose particles of carbon are removed on completion.
3. Check existing valve stem and head diameters.
4. Check valve stem to guide clearance using new valves.
5. Renew valves and guides as necessary. Valve head diameter A:
Inlet = 39.75 to 40.00 mm (1.5 to 1.6 in)
Exhaust = 34.226 to 34.48 mm (1.3 to 1.4 in)
Valve stem diameter B:
Inlet = 8.664 to 8.679 mm (0.341 to 0.342 in)
Exhaust = 8.651 to 8.666 mm (0.340 to 0.341 in)
6. Check installed height of each valve.
Valve installed height C = 47.63 mm (1.9 in)
7. Renew valve/valve seat insert as necessary.
8. Check valve stem to guide clearance.
Valve stem to guide clearance D:
Inlet = 0.025 to 0.066 mm (0.001 to 0.002 in)
Exhaust = 0.038 to 0.078 mm (0.0015 to 0.003 in)
9. Check condition of valve springs:
Free length = 48.30 mm (1.90 in)
Fitted length = 40.40 mm (1.60 in)
Load - valve closed = 339 ± 10 N (76 ± 2 lbf)
Load - valve open = 736 ± 10 N (165 ± 2 lbf)
NOTE: Valve springs must be replaced as a complete set.
Valve Guides - Renew
1. Using valve guide remover, LRT-12-037 press valve guide out into combustion face side of cylinder head.
NOTE: Service valve guides are 0.025 mm (0.001 in) oversize on outside diameter to ensure interference fit.
2. Lubricate new valve guide with engine oil and place in position.
3. Using LRT-12-038 partially press guide into cylinder head, remove tool.
4. Fit LRT-12-515 over valve guide and continue to press guide into cylinder head until tool LRT-12-038 contacts tool LRT-12-515; remove tool.
Valve guide installed height A = 15.0 mm (0.590 in)
5. Ream valve guides to 8.70 mm (0.34 in) diameter.
6. Remove all traces of swarf on completion.
Valve Seat Inserts - Inspection
1. Check valve seat inserts for pitting, burning and wear. Replace inserts as necessary.
Valve Seat Inserts - Renew
NOTE: Service valve seat inserts are available 0.025 mm (0.001 in) oversize on outside diameter to ensure interference fit.
1. Remove worn valve seats.
CAUTION: Take care not to damage counterbore in cylinder head.
2. Heat cylinder head evenly to approximately 120 °C (250 °F).
WARNING: Handle hot cylinder head with care.
3. Using a suitable mandrel, press new insert fully into counterbore.
4. Allow cylinder head to air cool.
Valve Seats And Seat Inserts - Refacing
CAUTION: Renew worn valve guides and seat inserts before lapping valves to their seats.
1. Check condition of valve seats and valves that are to be re-used.
2. Remove carbon from valve seats.
3. Reface valves as necessary. If a valve has to be ground to a knife-edge to obtain a true seat, fit a new valve.
Valve seating face angle A = 45°
4. Cut valve seats using LRT-12-501 with LRT-12-503 and LRT-12-517.
Valve seat:
Width A:
Inlet = 36.83 mm (1.45 in)
Exhaust = 31.50 mm (1.24 in)
Seating width B:
Inlet = 0.89 to 1.4 mm (0.035 to 0.055 in)
Exhaust = 1.32 to 1.83 mm (0.052 to 0.072 in)
Angle C= 56 ° to 70 °
Angle D= 46 ° to 46 ° 25 °
Angle E= 20 °
5. Ensure cutter blades are correctly fitted to cutter head with angled end of blade downwards, facing work, as illustrated. Check that cutter blades are adjusted so that middle of blade contacts area of material to be cut. Use light pressure and remove only minimum of material necessary.
6. Remove all traces of swarf on completion.
Valves - Lapping-in
1. Lap each valve to its seat using fine grinding paste.
2. Clean valve and seat.
3. Coat valve seat with a small quantity of engineer's blue, insert valve and press it into position several times without rotating. Remove valve and check for even and central seating. Seating position shown by engineer's blue should be in centre of valve face.
4. Check valve installed height if valve seats have been recut or new valves or valve seat inserts have been fitted.
Valve installed height A = 47.63 mm (1.9 in) - maximum
5. Thoroughly clean cylinder head, blow out oilways and coolant passages.
Valves And Springs - Refit
1. Fit new valve stem oil seals, lubricate valve stems, fit valves, valve springs and caps, compress valve springs using LRT-12-034 and fit collets.
2. Using a wooden dowel and mallet, lightly tap each valve stem two or three times to seat valve cap and collets.
3. Fit spark plugs and tighten to 20 Nm (15 ft. lbs.).
Cylinder Head - Refit
1. Clean cylinder block and cylinder head faces using suitable gasket removal spray and a plastic scraper.
2. Ensure that bolt holes in cylinder block are clean and dry.
CAUTION: Do not use metal scraper or machined surfaces may be damaged.
3. Fit cylinder head gasket with the word TOP uppermost.
NOTE: Gasket must be fitted dry.
4. Carefully fit cylinder head and locate on dowels.
5. Lightly oil threads of new cylinder head bolts.
NOTE: RH cylinder head illustrated.
6. Fit new cylinder head bolts:
Long bolts: 1, 3 and 5
Short bolts: 2, 4, 6, 7, 8, 9 and 10
7. Using sequence shown, tighten cylinder head bolts to:
Stage 1 - 20 Nm (15 ft. lbs.)
Stage 2 - 90 degrees
Stage 3 - Further 90 degrees
CAUTION: Do not tighten bolts 180 ° in one operation.
8. Fit rocker shaft assembly.
9. Repeat above procedures for remaining cylinder head.