Piston Assemblies
Piston Assemblies
Service Repair No - 12.17.02.01
Disassembly
1. Remove cylinder head assembly.
2. Remove oil pick-up strainer.
3. Suitably identify each connecting rod and piston assembly to its respective cylinder bore.
4. Remove 2 bolts securing each connecting rod bearing cap.
5. Remove connecting rod bearing cap and collect connecting rod bearings.
6. Remove ridge of carbon from top of cylinder bores.
7. Carefully push each piston assembly from the top of the cylinder.
CAUTION: Ensure that connecting rods do not contact cylinder bores.
8. Refit bearing cap onto connecting rod, lightly tighten dowel bolts.
9. Suitably identify each piston to its respective connecting rod.
10. Position body of tool LRT-12-013 in vice.
11. Screw large nut back until flush with end of center screw,
12. Push center screw forward until nut contacts thrust race.
13. Locate piston adapter tool LRT-12-126/2 with its long spigot inside bore of hexagon body.
14. Position guide pin tool LRT-12-12613 in hexagon body with groove facing away from piston.
15. Locate piston and connecting rod assembly on center screw and up to adapter tool LRT-112126/2.
16. Fit remover/replacer bush tool LRT-12-126/1 on center screw with flanged end facing away from gudgeon pin.
17. Screw stop nut onto center screw leaving clearance of 3 mm (0.125 in), dimension 'A', between nut and remover/replacer bush.
18. Lock the stop nut securely with lock screw.
19. Push connecting rod to locate end of gudgeon pin in adapter tool LRT-12-126/2.
20. Ensure remover/replacer is located in gudgeon pin bore of piston.
21. Screw large nut up to tool LRT-12-013.
22. Hold lock nut and turn large nut until gudgeon pin is withdrawn from piston.
23. Dismantle tool and remove piston, connecting rod and gudgeon pin.
Inspect
1. Clean carbon from piston. Inspect piston for distortion, cracks and burning.
2. Remove piston rings from piston,
3. Measure and record piston diameter at 90° to gudgeon pin axis and 10 mm (0.4 in) from bottom of the skirt. The piston must be 0.02 to 0.045 mm (0.001 to 0.002 in) smaller than the cylinder bore.
4. Check gudgeon pin bore in piston for signs of wear and overheating.
5. Pistons fitted on production are graded 'A' or 'B', the grade letter is stamped on the piston crown.
^ Piston diameter: Grade 'A' = 93.970 to 93.985 mm (3.6996 to 3.7002 in).
^ Piston diameter: Grade 'B' = 93.986 to 94.00 mm (3.7002 to 3.7007 in).
6. Worn cylinders fitted with grade 'A' pistons may be honed to accept the grade 'B' piston provided that specified cylinder bore and ovality limits are maintained. Grade 'B' pistons are supplied as service replacements. Do not attempt to de-glaze cylinder bores.
7. Check gudgeon pins for signs of wear and overheating.
8. Check clearance of gudgeon pin in piston.0 Gudgeon pin to piston clearance = 0.006 to 0.015 mm (0.0002 to 0.0006 in).
9. Check overall dimensions of gudgeon pin. Gudgeon pins are only supplied as an assembly with replacement pistons.
^ Gudgeon pin length = 60.00 to 60.50 mm (2.362 to 2.382 in).
^ Gudgeon pin diameter = 23.995 to 24.00 mm (0.9446 to 0.9448 in).
10. Measure cylinder bore wear and ovality in two axis 40 to 50 mm (11.6 to 2 in) from top of bore. The temperature of piston and cylinder block must be the same to ensure accurate measurement. Do not attempt to de-glaze cylinder bores.
^ Grade 'A' pistons: Cylinder bore = 94.00 to94.015 mm (3.7007 to 3.7013 in).
^ Grade 'B' pistons: Cylinder bore= 94.016 to 94.030 mm (3.7014 to 3.7019 in).
^ Maximum ovality= 0.013 mm (0.0005 in).
11. Check alignment of connecting rods.
Reassembly
1. Pistons have a 5 mm (0.2 in) offset gudgeon pin which can be identified by an arrow mark on the piston crown. This arrow must always point towards the front of the engine.
2. Assemble pistons to connecting rods with arrow on piston pointing towards domed shaped boss on connecting rod for RH bank of cylinders and arrow pointing away from domed shaped boss for LH bank of cylinders.
3. Clamp hexagon body of tool LRT-12-013 in vice.
4. Loosen large nut and pull the center screw 50 mm (2 in) out of hexagon body.
5. Locate piston adapter tool LRT-12-126/2 with its long spigot inside bore of hexagon body.
6. Fit remover/replacer tool LRT-12-126/3, with groove towards piston, up to shoulder on center screw.
7. Lubricate gudgeon pin and bores of connecting rod and piston with graphite oil.
8. Locate connecting rod and piston to center screw with connecting rod entered on sleeve up to groove.
9. Fit gudgeon pin on to center screw and into piston bore up to connecting rod.
10. Fit remover/replacer tool LRT-12-126/1 with flanged end towards gudgeon pin.
11. Screw the stop nut on to center screw and position piston against groove of tool LRT-12126/3.
12. Lubricate center screw threads and thrust race with graphite oil, screw large nut up to tool LRT-12-013.
13. Lock the stop nut securely with lock screw.
14. Set torque wrench to 16 Nm (12 ft. lbs.) and using socket on large nut, pull gudgeon pin in until flange of tool LRT-12-126/1 is O.40mm (O.016 in), dimension 'A' from face of piston. If torque is exceeded during this procedure, fit of gudgeon pin to connecting rod is not acceptable and components must be replaced.
CAUTION: The center screw and thrust race must be kept well lubricated throughout the operation.
15. Dismantle tool, remove piston and check no damage has occurred during pressing and that piston moves freely on gudgeon pin.
16. Remove compression rings, oil control rails and expander from new piston.
17. Invert piston and with arrow pointing towards rear of cylinder block, insert piston into cylinder liner.
18. Position piston with bottom of skirt 30 mm (11.12 in) from top cylinder liner.
19. Using feeler gauges, measure and record clearance between piston and left hand side of cylinder- viewed from the front of cylinder block.
^ Piston to bore clearance = 0.020 to 0.045 mm (0.001 to 0.002 in).
20. Insert piston rings into cylinder bore, use the piston to hold the rings square to bore and check the ring gap.
^ 1st compression ring = 0.030 to 0.050 mm (0.012 to 0.02 in).
^ 2nd compression ring = 0.040 to 0.065 mm (0.016 to 0.026 in).
^ Oil control ring rails = 0.38 to 1.40 mm (0.015 to 0.055 in).
21. Remove piston rings from bore.
22. Fit oil control ring rails and expander, ensuring ends butt and do not overlap.
23. Fit 2nd compression ring marked 'TOP' with marking uppermost in 2nd groove.
24. Fit 1st compression ring in first groove either way round.
25. Check piston ring to groove clearance.
^ 1st compression ring= 0.020 to 0.060 mm (0.0008 to 0.0024 in).
^ 2nd compression ring = 0.020 to 0.052 mm (0.0008 to 0.0020 in).
26. Position oil control expander ring joint and ring rail gaps all at one side, between gudgeon pin and away from LH side of piston - viewed from front of piston. Position the gaps in ring rails approximately 25 mm (1.0 in) each side of expander ring joint.
27. Position compression rings with gaps on opposite side of piston between gudgeon pin and RH side of piston - viewed from front of piston,
28. Thoroughly clean cylinder bores.
29. Lubricate piston rings and gudgeon pin with clean engine oil.
30. Lubricate cylinder bore with clean engine oil.
31. Using a suitable piston ring clamp, compress piston rings.
32. Insert connecting rod and piston into its respective cylinder bore, ensuring domed shaped boss on connecting rod faces towards front of engine on RH bank of cylinders and towards rear on LH bank of cylinders.
33. Clean connecting rod journal and bearing cap.
34. Lubricate connecting rod journal and connecting rod bearings.
35. Fit connecting rod bearings and connecting rod bearing caps ensuring they are in their correct fitted order.
NOTE: The rib on the edge of the bearing cap must face towards the front of the engine on the RH bank of cylinders and towards the rear on the LH bank.
36. Fit bolts and tighten to 20 Nm (15 ft. lbs.) then turn a further 80°.
37. Fit oil pick-up strainer.
38. Fit cylinder head gasket.