Crankshaft: Service and Repair
Disassembling and assembling crankshaftTools
Disassembling crankshaft
1. Remove tensioning sleeve (6 x 16) with a vice-grip wrench.
2. Clamp retaining plate P 209 a in the vice.
3. Fasten the crankshaft to the retaining plate with 3 -pan-head screws- LO No. 928 102 151 01.
4. Loosen connecting rods with socket wrench insert M14 and remove.
5. Remove snap ring with snap ring pliers.
6. Remove spacer ring and timing gear with a conventional puller.
7. Raise Woodruff key with side cutters and remove.
8. Remove crankshaft from retaining plate.
9. Check crankshaft for shocks, cracks and wear.
10. Carry out sounding test.
Note:
^ Before assembling the connecting rods, check without fail the elongation of the ring knurled screws. If the dimension X (38.3 mm) is exceeded, the connecting-rod bolts must be replaced.
11. Check the connecting rods. Determine the length of the connecting-rod bolts.
Note:
^ In the case of the connecting-rod version with a 3-ring knurled screw, no replacement is possible. In this case, the entire connecting rod must be replaced. The 4-ring knurled screw is available as a spare part.
Identifying the ring knurled screw
Note:
^ The visual difference between the 3-ring knurled screw and the 4-ring knurled screw can only be detected when the screw is pressed out.
1. Identify the ring knurled screw. With the screw pressed in, measure the groove diameter.
Object Measured value Screw type
Diameter groove 1 > 7.9 mm 3-ring knurled screw
Diameter groove 1 < 7.9 mm 4-ring knurled screw
Pressing ring knurled screw in and out
Pressing ring knurled screw out
Caution: In order to protect the con-rod cover, always insert aluminum sheet strips at the sides into the vice.
1. Clamp the con-rod cover into a machine vice. Press both 4-ring knurled screws out at the same time.
Pressing ring knurled screw in
Caution: In order to avoid damage to the joint face, always use an aluminum sleeve, e.g. from the special tool set P140 (retainer sleeves for cylinders).
1. Guide the new 4-ring knurled screw by hand into the previous (old) toothing and then press it in up to the rest.
2. Re-allocate the con-rod cover and the connecting rod and lay to one side.
Assembling crankshaft
1. Clean crankshaft thoroughly.
2. Rinse out oil bores with a hand pump and solvent naphtha several times.
3. With a visual inspection, check whether the oil ducts are blocked at the bearing surfaces and on the front face (aluminum stoppers).
4. Clamp crankshaft.
5. Lubricate the con-rod journals with grease (Optimal Optipit) and mount the connecting rods on the crankshaft.
Note:
^ The matching numbers of the con-rods and the con-rod bearing caps must all point to the same side.
6. Tighten con-rod nuts.
7. After the tightening procedure, check the con-rod bolt for twisting.
8. Insert and align new Woodruff key for timing gear.
Note:
^ The collar of the timing gear must point to bearing 7!
^ As an assembly aid, remove the timing gear from the heat source e.g. with a piston restraining strap and quickly mount or push it into place on the journal.
9. Warm the timing gear to approximately. 150 - 200°C in an oil bath or on a heating plate and push it on to the crankshaft journal up to the stop.
10. Heat up the spacer ring in the same way and push it on up to the stop.
11. Mount snap ring.
Note:
^ The snap ring must be inserted without play!
The following snap rings are available:
Part number Thickness (mm) Identification
901.102.148.00 2.4 blank
901.102.148.01 2.3 tempered blue*
901.102.148.02 2.2 tempered yellow/brown
901.102.148.03 2.1 black, gun-metal finish
* most frequently used snap ring for first assembly
12. Select the corresponding snap ring using an insertion test.
13. The opening of the snap ring should lie opposite the Woodruff key groove.
14. Knock the snap ring into the retaining groove with a blunt chisel.
Location Thread Tightening torque Nm (ft. lbs.)
Connecting rod nut M9 x 1.25 Initial tightening: 30 Nm (22 ft. lbs.); final tightening: 1 x 90° torque angle