Remove/Disassemble
Removing piston, preliminary work1. Disassemble engine to crankcase.
Removing pistons
ATTENTION: Damage due to ingress of dirt
^ Oil bores/oil ducts can become blocked up.
^ When working on the engine, absolute cleanliness is essential.
^ Lay removed engine parts on a clean base and cover them without fail.
^ Use the cover for dust protection when fitting the engine NR.165 on the engine assembly support.
Note: Fix the gear carrier for removing the pistons with two auxiliary screws to crankcase half 1-3.
Note:
^ Mark pistons in installation position before removal. Combustion residues (carbon deposits) can be removed with a brass brush.
^ Hard to remove residues can be removed in the ultrasound bath following disassembly.
1. Unscrew inner Torx screws with O-ring (M9 x 94 inside and M9 x 84 outside) for gear carrier -arrows- on crankcase half 1-3.
2. Unscrew inner Torx screw with O-ring M9 x 140 for gear carrier -arrow- on crankcase half 4-6.
3. Turn crankcase at assembly support until crankcase half 4-6 stands vertically upwards.
4. Unscrew four coated M6 x 35 Torx screws -1- on crankcase half 4-6 on flywheel side. Replace screws during assembly.
5. Unscrew 20 remaining M6 x 35 Torx screws in the crankcase cross bolt connection.
6. Unscrew the star screw that fixes crankcase half 4-6 to the engine support -arrow-.
7. Tap the crankcase halves gently with a plastic hammer. Carefully lever the various cast lugs with a screwdriver to separate the crankcase halves from one another.
ATTENTION: Crankcase half 4-6 incorrectly levered off
^ Damage to pistons, piston rings
^ Lever off crankcase half 4-6 only with the help of a second person.
8. Carefully lever off crankcase half 4-6 with the help of a second person to avoid damaging the pistons (e.g. by tilting). Remove old shaft seals.
9. For the following steps, fasten the gear carrier to crankcase housing half 1-3 with two cylinder-head screws using spacer sleeves 9613. Tightening torque 15 ft. lbs.
Removing pistons, side 4-6
10. Lever off the front piston-pin circlips of marked pistons 4-6 (from the viewpoint of the drive belt side) using a small screwdriver, push out the piston pin -arrow- and remove the pistons one by one. Assign the piston pins again to the appropriate pistons.
Removing pistons and connecting rods, side 1-3
11. Remove marked pistons 1-3, including connecting rods. To do this, turn the crankshaft on the belt pulley/vibration balancer until the respective connecting rod bearing cap stands upwards. Undo and remove the connecting rod bolts (twelve-edged socket wrench insert a/f 14), remove connecting rod bearing cap.
Note:
^ Join connecting rod and connecting rod bearing cap together again immediately after removal,
^ Connecting rod bolts must be replaced.
12. Carefully press connecting rod and pistons downwards out of crankcase half 1-3 using a shop-made plastic mandrel. Allocate a connecting rod cap immediately to the relevant connecting rod and screw on loosely. Pay attention to the bearing shells.
13. Unscrew fastening screw for belt pulley/vibration balancer and remove washer or damper. In the case of the vibration balancer, pay attention to the friction plate.
14. To remove connecting rod 4-6, remove the gear carrier, Removing crankshaft, preliminary work
Disassembling pistons/connecting rods, cylinder 1-3
Note: When removing pistons, the piston-pin circlip always remains in the piston, which is installed opposite the large assembly bore (no chamfer) for the piston pin.
1. Remove piston/connecting rod unit. To do this, clamp the connecting rod to a vice with aluminum jaws, for example.
ATTENTION: Over-extension of piston rings
^ Damage or breakage
^ Using the piston ring pliers, spread open the piston rings only far enough so that the rings can be installed or removed (without scratching the piston).
2. Remove piston ring groove 1 and groove 2 separately using a piston ring pliers Gr. 1 NR.58. Remove piston ring groove 1 first. The piston rings must not be overstretched.
3. The three-piece oil scraper ring can be removed by hand. First, carefully remove both rings, then remove the springs.
4. Insert piston/connecting rod unit into the retaining device 9597 in such a way that the twist lock in the second piston ring groove faces the observer.
5. Carefully press out piston-pin circlip with a screwdriver; while doing so, place a cloth over the piston so that the circlip does not pop out.
6. Turn piston/connecting rod unit through 180° on the assembly device and press out piston pin with the plunger special tool assembly tool 9500.
7. Repeat steps for removing pistons/connecting rods on cylinders 2 and 3.