Crankshaft: Service and Repair
11 21 500 Replacing crankshaft (N74)Special tools required:
Important!
Weight of crankshaft is approx. 25 kg.
Risk of injury from sharp crankcase edges.
Necessary preliminary tasks:
^ Remove engine
^ Mount engine on assembly stand
^ Remove cylinder head.
^ Remove hub for vibration damper
^ Removing lower timing case cover
^ Removing oil pan
^ Remove oil pump
^ Removing piston
^ Remove flywheel
^ Remove radial shaft seals
^ Remove timing chains
Installation:
Arrangement of main bearing caps 1 to 7.
All numbers must be read from the cylinder bank (7 to 12) (see arrows).
Installation:
All bearing caps are numbered 1 to 6.
The bearing cap on bearing seat 7 has no number.
Main bearing caps 1 to 7 on the output end on the timing chain drive.
Release oil pump spacer bolts (1) with special tool 13 5 020.
Release main bearing taper screw mounting from 1 to 11.
Release all thread support bushings (1).
Release collar bolts (M8) in sequence 1 to 14.
Release collar bolts (M11) in sequence 11 to 14.
Remove main bearing caps 1 to 7.
Important!
Remove crankshaft with a 2nd person, weight approx. 25 kg.
Lift out crankshaft and set down safely (secure against turning).
Release screw for oil nozzle (1).
Tightening torque: 11 11 7 AZ.
Installation:
Check oil nozzle for clear passage with compressed air.
Observe fastening on oil nozzle.
Replace all O-rings.
Replace main crankshaft bearing shells.
Important!
Install crankshaft with a 2nd person, weight approx. 25 kg.
Install crankshaft.
Installation:
Observe arrangement of main bearing caps (1).
All numbers must be read from the cylinder bank (7 to 12) (see arrows).
Turn back all thread support bushings hand-tight.
The main bearing cap number 1 is on the timing chain drive.
Installation:
Coat all main bearing points with engine oil.
Fit main bearing caps (1 to 7).
Installation:
For a better overview of the screw connection quality, mark the head of all collar bolts after joining with a line (1) using an oil-proof marker pen.
For more accurately checking entire angle adjustment.
Insert collar bolts (M11) hand-tight in sequence (1 to 14).
(M11) Connect collar bolts in sequence (1-14) with 20 Nm torque.
To better check the total angular adjustment, mark all collar bolts M 11 with an oil-proof marker.
Secure collar bolts (M11) in sequence (1 to 14).
Secure collar bolt (1) with special tool 00 9 120.
Tightening torque: 11 11 1AZ.
Insert collar bolts (1 to M8) hand-tight in sequence.
(M8) Connect collar bolts in sequence (1-14) with 10 Nm torque.
To better check the total angular adjustment, mark all collar bolts with a line using an oil-proof marker.M8
Secure collar bolts (M8) in sequence (1 to 14).
Secure collar bolt (1) with special tool 00 9 120.
Tightening torque: 11 11 2 AZ.
Secure all threaded support sleeves (1) with special tool 11 4 350.
Tightening torque: 11 11 3 AZ.
Tighten down main bearing taper screw mounting from 1 to 11.
Tightening torque: 11 11 4 AZ.
Tighten down oil pump spacer bolts (1) with special tool 13 5 020.
Tightening torque: 11 11 5 AZ.
Check crankshaft coefficient of friction.
Determine crankshaft breakaway torque with special tool 00 2 010.
Rotate crankshaft at central bolt using special tool 00 2 010.
If the breakaway torque is too high, it will be necessary to correct the bearing clearance.
Secure special tool 11 6 252 to crankcase with magnetic base.
Slide crankshaft in direction of arrow forwards as far as it will go.
Set special tool 11 6 251 to zero.
Slide crankshaft (1) in direction of arrow towards rear and determine value.
Check axial play.
Assemble engine.
