Leak on TRANSMISSION 725.0 (9G
TRONIC) BR166/292/167 with 4MATIC
Topic number

LI27.00-P-067577

Version

3

Function group

27.00 General

Date

10-05-2020

Validity

Leak on TRANSMISSION 725.0 in BR166/292/167 with
4MATIC

Reason for change

For model series 167, gold/yellow oil is now being used
in the transfer case instead of red oil. It is not possible to
differentiate between the transmission oil and transfer case oil based on color in model series 167.

Reason for block

Complaint:

Leakage at transmission 725.0 (9G TRONIC) in area of transfer case/adapter housing.
If leakages are detected on the TRANSMISSION 725.0 (9G TRONIC), work through the tests with any remedial measures.

Attachments
File

Description

Öl im Bereich RWDR am Getriebe 725.0.jpg

Oil in radial shaft sealing ring area on transmission 725.0

Öl im Rundflansch am Getriebe 725.0.jpg

Oil in round flange on transmission 725.0

Cause:

- Tightening torque on collar nut (output shaft)
- Leakage at transfer case
- Leakage at radial shaft sealing ring (RSS)

Remedy:

For model series 166/292, the leakage can be localized by checking the oil color:
For better differentiation of the oil, drops should be placed onto a white sheet of paper:
- Gold/yellow oil leaks from transmission 725.0 (9G TRONIC). If gold/yellow oil detected: Check if oil is visible on
round flange/collar nut:
- Red oil leaks from the transfer case
For model series 167, the leakage is localized by the position of the leakage.
10-05-2020 9:42 PM
© Copyright Mercedes-Benz AG

KATSELF

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*Notes: From model series 167, gold/yellow oil is now being used in the transfer case instead of red oil.
If gold/yellow oil is visible on round flange:
1. Assess caulking of collar nut and determine release torque of collar nut
2. Replace collar nut (B) and round flange (A), clean everything beforehand
3. Tighten new collar nut to 220 ± 20 Nm (initial tightening torque), then release collar nut by 30°, finally tighten collar
nut again to 200 ± 20 Nm (second tightening torque)
4. Caulk new collar nut according to specification
5. Specify damage code 27332 38
If gold/yellow oil is visible in area of radial shaft sealing ring (RSS):
1. Remove RSS
2. Check position of retaining ring opening
3. If necessary, use retaining ring pliers (see picture "Retaining ring pliers.jpg") to turn it to the "7 o'clock position" (see
example picture "Verdrehen auf 7Uhr_Turn to 7oclock.jpg")
*Note: The ventilation hole on the housing must not be covered by the retaining ring.
4. Replace the RSS; coat the new RSS with transmission oil and press in using the special tool; observe AR27.40p-0206EWM
5. Clean everything beforehand and replace collar nut (B) and round flange (A)
6. Tighten new collar nut to 220 ± 20 Nm (initial tightening torque), then release collar nut by 30°, finally tighten collar
nut again to 200 ± 20 Nm (second tightening torque)
7. Caulk new collar nut according to specification
8. Specify damage code 27311 04.
In the event of red oil or gold/yellow oil from the transfer case (see fault profile "Gold/yellow oil from transfer case of
model series 167.jpg"):
Repair transfer case in accordance with WIS specification and assign corresponding damage code.

Attachments
File

Description

Verdrehen auf 7Uhr_Turn to 7oclock.jpg

If necessary, turn to "7 o'clock" position (see example picture "Turn to 7 o'clock.jpg") using retaining ring pliers (see
picture "Retaining ring pliers.jpg")
*Note: The ventilation hole on the housing should not be
covered

Gold-Gelbes Öl aus dem Verteilergetriebe der BR167.jpg Gold/yellow oil from the transfer case of model series 167

Symptoms
Power transmission / Automatic transmission / Leakage / Leaks
10-05-2020 9:42 PM
© Copyright Mercedes-Benz AG

KATSELF

Page 2/3

Parts
Attachments
File

Description

Bundmutter (B) und Rundflansch (A) am GETRIEBE 725. Collar nut (B) and round flange (A) on TRANSMISSION
0.JPG
725.0.
Sicherungsring Zange.jpg

Retaining ring pliers

Operation numbers/damage codes
Op. no.

Operation text

10-05-2020 9:42 PM
© Copyright Mercedes-Benz AG

Time

KATSELF

Damage
code

Note

27332 38

Bolt/nut for output flange for automatic transmission loose

27311 04

Radial shaft sealing ring on transmission housing at rear leaky

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