Replace/weld on connection fittings for sensors of exhaust gas aftertreatment unit

AR49.20-W-1002-01H

Replace/weld on connection fittings for sensors of exhaust gas aftertreatment unit

 Caution

Risk of injury caused by scraping or cutting body parts on sharp vehicle parts

Always wear protective gloves when working on or near sharp and non-deburred vehicle parts.
Deburr repair panels.

AS00.00-Z-0017-01A

 Warning

Risk of injury. Skin or eye injuries may result when handling hot or glowing objects.

Wear protective gloves, protective clothing and safety glasses, if necessary.

AS00.00-Z-0002-01A

 Danger

The high voltage used for electric welding presents a lethal hazard. Risk of explosion from welding in areas close to highly inflammable materials. Risk of injury from weld splatter and UV-light when welding. Risk of poisoning from inhaling welding gases

Use insulating mats. Wear protective clothing, safety glasses and a protective mask. Remove highly inflammable materials from the hazard area. Use air extraction system.

AS00.00-Z-0007-01A

Topical note

Notes on self-locking nuts and bolts

AH00.00-N-0001-01A

Note on calculation of tightening torque when using insertion or socket tools with various effective lengths

AH00.00-P-0015-01CW

General information and guidelines for welding on the exhaust aftertreatment unit

AH49.20-N-0001-01A

Engine

470.9, 471.9, 473.9 in model 963, 964

 Exhaust system

Number

Designation

Engine 470.9, 471.9

Engine 473.9

BA49.10-N-1004-02A

Exhaust temperature sensor to exhaust aftertreatment unit

Nm

30

30

 Exhaust system

Number

Designation

Engine 470.9, 471.9

Engine 473.9

BA49.10-N-1005-02A

NOx sensor to exhaust aftertreatment unit

Nm

50

50

 Exhaust system

Number

Designation

Engine 470.9, 471.9

Engine 473.9

BA49.10-N-1023-02A

Pressure line to exhaust aftertreatment unit

Nm

12

12

Repair materials

Number

Designation

Order number

BR00.45-Z-1103-06A

Paste, hot lubrication 100 g DBL 6879.20

A 000 989 76 51 11

The following work instructions describe the simultaneous replacement of three different connection fittings:

1

Remove pressure line (2) that leads to exhaust gas pressure sensor upstream of diesel oxidation catalytic converter (B37) at exhaust gas aftertreatment unit (1).

2

Remove exhaust gas temperature sensor upstream of diesel oxidation catalytic converter (B67) and exhaust gas aftertreatment unit inlet NOx sensor (A70 b1).

 Only place tool on hexagon of the union nut.
Component parts are very sensitive and can be easily destroyed.

 If a sensor cannot be removed because the thread has seized, this will be bored out in the next operation step.

3

Select the appropriate milling bit crown (3), associated centering (4) as well as associated mount (5) from the tool kit  welding fixture.

 The following milling bit crowns (3) must be used for the connections (6, 7, 8):
Pressure line: Ø 23 mm
Temperature sensor: Ø 32 mm
NOx sensor: Ø 38.5 mm

4

Drill out affected connections (6, 7, 8) using a drill and the selected milling bit crown (3).

5

Deburr edges of holes.

6

Smooth and clean surrounding area of holes using a wire brush (9).

7

Insert affected connection fittings (10, 11, 12).

 Use following parts:
Connection fitting (10) for pressure line: A 007 997 53 71
Connection fitting (11) for temperature sensor: A 007 997 52 71
Connection fitting (12) for NOx sensor: A 007 997 51 71

8

Protect thread of connection fittings (10, 11, 12) against welding splatter by attaching screw plugs (13, 14) and/or nut (15).

 No foreign objects may enter into interior of exhaust gas aftertreatment unit (1).
This could otherwise result in damage.

9

Align affected connection fittings (10, 11, 12) and initially tack weld for securing purposes.

 During the alignment, ensure that any gap between jacket of exhaust gas aftertreatment unit (1) and connection fittings (10, 11, 12) is as small as possible.

 The following parts must be used to protect the thread during welding:
For connection fitting (10) of pressure line: N 000000 005461 (nut)
For connection fitting (11) of temperature sensor: N 000908 014009 (screw plug)
For connection fitting (12) of NOx sensor: N 000908 020004 (screw plug)

10

Weld in connection fittings (10, 11, 12).

 Ensure that there are no leaky locations.
Malfunctions of exhaust gas aftertreatment unit (1) can otherwise occur.

11

Install pressure line (2)  .

 Coat thread with lubricant.

12

Install exhaust gas temperature sensor upstream of diesel oxidation catalytic converter (B67) and exhaust gas aftertreatment unit inlet NOx sensor (A70 b1)    .

 Only place tool on hexagon of the union nut.
Component parts are very sensitive and can be easily destroyed.

 Coat thread with lubricant.