39 Oil leak at sealing cap on rear final drive, sport differential
39 21 44 2064024/1 August 26, 2021.
Model(s)

Year

VIN Range

Vehicle-Specific Equipment

RS6 Avant,
RS7, SQ7,
SQ8, RSQ8,
and S8

2020 - 2021

All

V8 & Sport differentials

Condition
Customer states:
 There is an oil leak from the rear of the vehicle.
Workshop findings:
 An oil leak is confirmed from the top of the
differential near the output flanges.
 One or both of the sealing caps are missing
from the pressure limiting valves (Figures 1
- 3).

Figure 1. Missing sealing cap viewed with a pocket mirror.

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© 2021 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of Audi of
America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.

Figure 2. Location of sealing caps on the 0D3 differential.

Figure 3. Location of sealing caps on the 0BX differential.

Technical Background
Not applicable.

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© 2021 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of Audi of
America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.

Production Solution
Not applicable.

Service
If the leak can be confirmed to be from a missing sealing cap, then perform the following repair.
The following parts are required to perform the repair:
 Repair Kit 0BX 598 080 contains two sealing caps and one special installation drift for the repair.
 Locking fluid, 10ml D 154 100 A1.
 Silicone adhesive sealant, 50ml D 176 501 A1.
1.

Following the Elsa Repair Manual instructions remove the differential from the vehicle and place it on a
suitable working surface.
Note:
The clutch valves can be damaged if subjected to impact. Place a rubber mat or hard foam slab underneath
the differential.

2.

Clean the rear differential around the pressure limiting valve (sealing cap missing) with a clean cloth. If only
one sealing cap is missing, do not attempt to remove the installed cap.
Note:
The bolt head on the pressure limiting valve (hexagon socket head bolt in the hole) must not be turned.
Note:
Chemical agents (brake clean etc.) must not enter the system. Do not let chemical agents get into the
exposed pressure limiting valve.
Tip: Steps 3 to 7 must be performed within 5 minutes (due to hardening of locking fluid).

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© 2021 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of Audi of
America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.

3.

Place the new sealing cap on a drift and coat it
lightly with locking fluid around the outside edge
(red arrow Figure 4).

Figure 4. Sealing cap on a drift.
4.

Knock sealing cap onto pressure limiting valve
using a drift and soft-faced hammer at a right
angle to machined surface of housing until it
reaches its stop. When it reaches its stop, a dull
sound can be heard and a spring-back effect
can be felt at the hammer (Figure 5).

Figure 5. Installing sealing cap
5.

Remove excess locking fluid with a clean cloth.

6.

Perform a visual check to see whether the sealing cap has been installed evenly around the entire
circumference.

7.

Perform a check measurement with a caliper gauge. The measurement from the machined surface of the
housing (the red area in Figure 6) to the upper collar of the sealing cap (green arrows in Figure 6).
This measurement must be performed in three locations at intervals of 120°and a minimum dimension of
1.00 mm and a deviation of no more than 0.3 mm must be ensured.
In the event of deviations from the minimum dimension or the maximum deviation being exceeded, the
sealing cap can be knocked carefully in with the drift and soft-faced hammer if necessary.

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© 2021 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of Audi of
America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.

Note:
It is not permitted to remove a sealing cap that has already been installed.

Figure 6. Measurement locations.
8.

Figure 7. Performing measurement.

If both sealing caps were missing, then follow the above instructions in steps 3 through 7 to install the 2nd
cap.

The following section of the repair instructions must be performed both for the renewed sealing caps and for
sealing caps that are still fitted from the factory. The sealing caps for pressure limiting valves on both sides must
be bonded on.
9.

After a drying time of at least 30 minutes, clean the area around the sealing caps of the pressure limiting
valves (both sides) using a clean cloth (lightly coated with brake cleaner if necessary).

10. Both sealing caps must be bonded over the entire surface using the silicone adhesive sealant. A layer of
skin forms and then hardens (Figures 8 - 9). A drying time of at least 30 minutes must be ensured before
reinstallation into the vehicle.

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© 2021 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of Audi of
America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.

Figure 9. Silicone adhesive sealant example 2.

Figure 8. Silicone adhesive sealant example 1.
11. Following the repair manual reinstall the differential into the vehicle. Take care not to touch the silicone
sealant as it takes a long time to completely harden.
12. Check ATF level of differential in accordance with Elsa Repair Manual and top up if necessary.

Warranty
Claim Type:

 110 up to 48 Months/50,000 Miles.
 G10 for CPO Covered Vehicles – Verify Owner.
 If the vehicle is outside any warranty, this Technical Service Bulletin is informational
only.

Service Number:

3989

Damage Code:

0050

Labor Operations: Remove and install rear final drive

3988 19XX

See SRT with
associated
operations

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© 2021 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of Audi of
America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.

Diagnostic Time:

Claim Comment:

Seal housing for the rear final drive

3989 5199

90 TU

Check and top up ATF for the rear final drive

0156 3599

20 TU

GFF – Checking and clearing fault codes
included in existing labor operations

No allowance

0 TU

Road test prior to service procedure

No allowance

0 TU

Road test after service procedure

0121 0004

10 TU

As per TSB #2064024/1

All warranty claims submitted for payment must be in accordance with the Audi Warranty Policies and Procedures
Manual. Claims are subject to review or audit by Audi Warranty.

Required Parts and Tools
Always check with your Parts Department and/or ETKA for the latest information and parts bulletins.
Part Number

Part Description

Quantity

See ETKA

Fasteners, Bolts, Nuts and Screws as needed per the
Repair Manual

See ETKA/ELSA

0BX598080

Repair kit for sealing cap

01

D154100A1

Locking fluid 10ml

01

N 90281802

Seal Bolt with seal ring

01

D176501A1

Silicone adhesive sealant 50ml

01

Additional Information
All parts and service references provided in this TSB (2064024) are subject to change and/or removal.
©2021 Audi of America, Inc. All rights reserved. Information contained in this document is based on the latest
information available at the time of printing and is subject to the copyright and other intellectual property rights of
Audi of America, Inc., its affiliated companies, and its licensors. All rights are reserved to make changes at any
time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted in
any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these
materials be modified or reposted to other sites without the prior expressed written permission of the publisher.

Page 7 of 7
© 2021 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of Audi of
America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.