Installing Pistons and Cylinders
NOTE:
- Observe installation sequence
- The central pistons of cylinders 2 and 5 are fitted on the connecting rod without cylinder liner.
- The pistons of the outer cylinders 1 - 3 and 4 - 6 are pre-fitted in the cylinder.
View of the outer pistons
1. Fit individual piston. Align the gaps of the piston rings offset by 120°.
CAUTION:
Risk of damage!
- Pay attention to the oil scraper rings when tightening the restraining strap
2. Apply a generous coat of oil on the piston. Mount a commercially available restraining strap. Position special tool 9659 at the top of the piston (piston junk).
3. Align the restraining strap. The restraining strap latch should be aligned between the inlet valve recesses.
NOTE:
- The assembly sleeve serves to position the restraining strap.
- Work swiftly when positioning, so as to avoid damaging the piston rings.
4. Insert the piston upside down into the assembly sleeve (special tool 9657). Push the piston down swiftly and simultaneously push the restraining strap down with the other hand.
5. Turn the belt pulley or crankshaft clockwise until the connecting rods of cylinders 2 and 5 are at top dead centre.
6. Mount the piston on the connecting rod. Push in the oiled piston pin as far as it will go.
NOTE:
- When pressing the circlip into the piston, it is recommended to enlist the aid of another person.
- Cover the crankcase housing hole under the piston to prevent the circlip from falling into the crankcase.
- After fitting, visually check whether the circlips are correctly seated.
7. Place assembly sleeve 9500/5 with pre-fitted piston pin circlip onto the piston pin eye. Insert the plunger into the conical assembly sleeve. The smaller diameter of the plunger serves as a guide in the piston pin. Use the plunger to push the circlip into the piston pin retaining groove in the piston. The circlip must audibly engage.
Position of the circlip
8. Prepare cylinders, outer cylinder liners and pistons for installation.
- Put new O-rings in the cylinders. Generously grease area of the O-rings.
- Fit new O-rings on the cylinder liners. Generously grease area of the O-ring.
- Fit outer cylinder liners in the cylinders. Align cylinder liners in the cylinders. The flats must face the other cylinder liners in longitudinal direction.
- The cutouts on the cylinder liner must be aligned with the holes for the studs.
- Fit outer cylinder liners using the pushing device (special tool 9660).
View of the assembly tool
- If necessary, the outer cylinder liners can also be pressed in with a hydraulic press.
NOTE: Before the two outer pistons are fitted, the outer piston pin circlip should have already been fitted in each case.
- Oil piston skirt. Mount a commercially available piston restraining strap. Push piston into the cylinder liner. When doing so, push the piston restraining strap down as well.
- Check position of the pistons. The large inlet valve recesses on the piston must face upward with the piston in installation position. If necessary, turn the piston in the cylinder liner. Pull piston out again until it is just possible to push in the piston pin.
9. Fit piston pin into the associated piston from the inner side. The piston pin must be inserted only far enough to permit the connecting rod to be fitted.
10. Make sure the piston is in the correct installation position. The large valve recesses must face upward in installation position.
11. Fit cylinder base seal over the studs.
12. Place spacers (special tool 9651) onto the outer studs.
13. Push preassembled cylinder onto the studs.
NOTE: Ensure piston pin circlips are properly seated!
14. Fit piston pin and piston pin circlip of the outer pistons from the inside (through the centre cylinder opening).
15. After fitting the piston pin circlips, push the cylinder to the spacers 9651. Secure the cylinder with special tool (holder P 140).
16. Prepare central cylinder liner. Fit a new O-ring and grease generously.
17. Position cylinder liner on the studs.
18. Fit pushing device 9660 on the studs. Lay the plastic washer on the cylinder liner and press the cylinder liner into place on the piston by turning the hand wheel.
View of the special tool
19. Slowly turn the belt pulley or crankshaft clockwise until the centre piston is no longer visible in the gap between the cylinder and crankcase. Then press the cylinder liner in with the pushing device until the restraining strap disengages from the piston skirt.
20. Open the restraining strap latch using two screwdrivers and pull the restraining strap out between the crankcase and the cylinder liner.
21. Then push the centre cylinder liner in with the hand wheel until it meets the stop.
22. Remover holder P 140 from the studs.
23. Remove spacers 9651 between the crankcase and the cylinder.
24. Then push the cylinder toward the crankcase and move it to installation position.
25. Secure the horizontal cylinder bank with holder P 140 to prevent it from being pushed out during subsequent assembly steps or when the crankshaft is turned.