Checking and reconditioning the crankshaft - ra03006010318x(0318)

WARNING: This page does not describe the selected car, but rather 42 other vehicles, including the 1999 Mercedes-Benz S600, 1999 Mercedes-Benz S500, 1999 Mercedes-Benz S420, 1999 Mercedes-Benz S320, and 1999 Mercedes-Benz CL600. However, it is still accessible from the selected car via links, so may be relevant.

Engines 601, 602 (except 602.98), 603

Preliminary jobs:

Crankshaft removed.

Fig 1: Identifying Crankshaft

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Crankshaft	clean
Crack test	perform; apply fluorescent powder (magnaflux) or use penetration method.
Hardness test (scleroscope hardness)	perform with impact hardness tester 000 589 20 21 00.
Distance (A = 5 - 6 mm)	when hardening journals without hardened fillets, maintain distance A between hardened runout and fillet radius.
Journals	can be hardened inductively or with flame.

Harden journals with hardened fillets (arrows) inductively only.

DATA

Crankshaft normal dimensions and repair stages

Crankshaft bearing journal dia.

Fitted bearing Associated thickness of thrust washers

Width of journal

Connecting rod bearing journal dia.

Connecting rod bearing journal width

Standard dimension

57.940

2.15

26.52⁽¹⁾

24.53⁽²⁾

47.940

27.96

26.50

24.50

57.965

2.20

26.62⁽¹⁾

24.63⁽²⁾

47.965

28.04

26.60

24.60

1st repair stage

57.700

2.25

26.72⁽¹⁾

24.73⁽²⁾

47.700

-28.30

57.715

26.70

24.70

47.715

2nd repair stage

57.450

47.450

57.465

26.92⁽¹⁾

24.93⁽²⁾

47.465

3rd repair stage

57.200

2.35

26.90

24.90

47.200

57.215

47.215

4th repair stage

56.950

2.40

27.02⁽¹⁾

25.03⁽²⁾

46.950

56.965

27.00

25.00

46.965

⁽¹⁾	1) Up to 06/84

⁽²⁾	2) Starting 07/84

TEST VALUES

Permissible deviation of crankshaft main and rod journals in mm		0.005
Permissible conicity of crankshaft main and rod journals in mm		0.01
Permissible roughness of crankshaft main and rod journals (Ra) in mm		0.005 - 0.015
Permissible deviation of flywheel flange from true in mm		0.02
Permissible axial runout of fitted bearing in mm		0.02
Fillet radii in mm	on crankshaft main journals	2.5 - 3.0
	on rod journals	3.0 - 3.5
Permissible deviation of crankshaft main journals when mounted in outer crankshaft bearing journals in mm	Journal II, IV	0.16
	Journal III	0.25

Special tool

Fig 2: Identifying Special Tool (000 589 20 21 00)

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

NOTE: When testing and reconditioning crankshafts, proceed in sequence shown in diagram below.

Testing, grinding

Fig 3: Grinding Test Flow Diagram
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Hardening

Fig 4: Hardening Flow Diagram

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Crack test

Clean crankshaft. Bearing journals should be free of oil and grease.

Magnetize crankshaft and apply fluorescent powder (magnaflux).

A color penetration method may also be used (immersion in bath or using spray can).

Fig 5: Checking Crankshaft Crack Test

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Agent:

Paint or fluorescent powder, cleaning agent, developer

Hardness test

Test hardness with impact hardness tester 000 589 20 21 00 (scleroscope hardness).

The minimum hardness of 55 should be present on 2/3 of journal circumference.

Hardening

Journals without hardened fillets can be hardened inductively or flame-hardened.

Journals with hardened fillets (arrows) must always be hardened inductively.

If this is not possible, scrap crankshaft.

Fig 6: Locating Crankshaft Journals

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Checking hardening results

To achieve perfect hardening check adjustment of hardening equipment using microsections.

These can be obtained from scrapped crankshafts hardened for testing purposes.

Check hardening by etching the journal surface with a 2 % solution of alcoholic nitric acid (HNO₃ ).

Dark spots should not appear on the journal surface.

Unhardened fillets will become dark.

On the other hand hardened fillets should be as bright as the surface of the journals.

We recommend comparing the etching test with a journal tested via metallographic microsection.

Then carefully wash off nitric acid with alcohol.

Corrosion protection

Crankshafts which are not installed again immediately should be lubricated with engine initial operation oil (SAE 30).