Crankshaft assembly,  OM617

Checking and reconditioning of crankshaft



03—318 Checking and reconditioning of crankshaft




Crankshaft standard dimension and repair stages
Crankshaft bearing journal dia.
Fitted bearing Pertinent thickness Width of of thrust washers journal
Crankpin dia.
Width of pins
Standard dimension
69.96 69.95
2 15 3400 34.03
51.96 51.95
2 20 3410 34.13
1st repair stage
69.71 69.70
34.20 2 25 34.23
or or
2 35 34.40
or or
2.40 34.50 34.53
51.71 51.70
to 32.30
2nd repair stage
69.46 69.45
51.46 51,45
3rd repair stage
69.21 69.20
51,21 51.20
4th repair stage
68.96 68.95
50.96 50.95


Permissible out-of-round of crankshaft journals and crankpins


Permissible conicity of crankshaft journals and crankpins


Permissible radial runout of flywheel flange


Permissible axial runout of fitted bearing


on crankshaft bearing journals
2.5 to 3.0




on crankpins
3.0 to 3.5


Permissible radial runout of crankshaft journals when mounted on outer journals
journal II, V
journal III, IV


Scleroscope hardness of crankshaft journals and crankpins


Permissible unbalance of crankshaft
15 cmg








The bearing journals of crankshaft are not inductance hardened similar to other engines, but are hardened in a nitride bath.
Contrary to inductance hardened crankshaft, a bath-nitrided crankshaft is hardened at its entire surface.


Conventional hardness tester (hardness drop tester) provides no information concerning proper hardness (depth of connecting layer) for crankshafts hardened in a nitride bath. No hardness test according to the above method is therefore required.


When testing and reconditioning crankshafts, proceed in sequence of diagram below.




* Refer to section “Explanations Concerning Diagram” V = scrap.






om617 - 0097-1.jpg






Explanations concerning diagram


Crack test


Clean crankshaft. Bearing journals should be free of oil and grease.
Magnetize crankshaft and apply fluorescent powder (fluxing).
A color penetration test (immersion in bath or using spray can) may also be applied.
Aid: Paint or fluorescent powder Cleaning agent Developer


Crankshaft must be nitride-hardened in a salt bath.
Prior to nitriding, close all threaded bores in crank­shaft.


Hardened threads will loose in strength and may therefore break out when tightening screws.
Screw-in necked-down screws on flywheel flange.
Screw-in a hollow center screw M 18 x 1.5 x 45 at front on crankshaft.


Center screw is bored hollow to prevent a chemical reaction in salt bath caused by the air which might be enclosed behind screw.
Duration and bath temperature are shown in nitriding specifications included upon delivery of nitriding equipment.
To avoid distorsion of crankshaft, suspend crankshaft vertically into nitriding bath.


03.8-318/4 F2