Greetings folks,
So I have a 2010 Audi Q7 3.0 TDI RHD(Right Hand Drive),and needs to remove and replace the Brake Master Cylinder. I've already ordered one,P/N 7L8611019G for a RHD,and 7L8611019F is for a LHD model. As is most things on these Audi's,it seems to be a real pain in the A*** to get to.!! Now, standing in front of your vehicle facing it, it's located to your left, inside the cowl under the windscreen wiper, next to the ECU(a very weird place to put this highly sensitive electronic equipment),behind the firewall. A very cramped and confined space indeed. I've added some photos. So if anyone has had any experience in removing the BMC before in a RHD model, or even a LHD and can offer any advice or suggestions before I start the process, will be very much appreciated!!

 

I'm just gonna go ahead and ask; why are you replacing the brake master cylinder...braking issues, leak below the master cylinder, what exactly prompted you to undertake this particular replacement?

FWIW:
I wouldn't dive into a brake master cylinder, even if it is leaking obviously, or most any other major DIY projects without first referencing to the Audi repair manual, or a similar resource. I bought a downloadable version, for example, on the cheap. The reason I'd not just 'have at it' on this car is Audi tends to throw some monkey wrenches in there between single use fasteners, required procedures and system calibrations, and of course the torque values and whatever gaskets, seals, and who knows what else. Even bleeding the brakes has a very specific procedure and sequence that needs to be followed verbatim on the Q7 to do it correctly and get ALL the air out of the entire system, which includes the ABS, etc.

 

There is also a section on this forum (up in the red banner, furthest to right), called How-tos...and it does offer some general referential material, but not specific to the Q7, in this case. It's also lacking in the details the actual repair manual will provide you, but it is 'something', at least. A lot of the DIY owners on here either buy the downloadable repair manual, or they go to a repair support site like Erwin, get a couple hours or day pass, then download everything they want off that platform, but w/o the cost of subscribing to it.

https://www.audiworld.com/how-tos/

 

Was kinda anticipating as to why the need to replace BMC...so,basically.. here goes..
Never had any braking issues, ever..until last week on my way home, after stopping at about 3 red lights without issues, on the 4th red, tried depressing the pedal mildly as I usually do, vehicle didn't slow or stopped until my foot went almost straight to the floor .
Just like that, without any noticeable warning. Note that I also did not get any warning indication lights on the dash display. Reached home safely after driving at about 10 kms per hour, and several young teens passed me popping their horns driving their JDM(Japanese Domestic Market) Hondas and Toyotas,overjoyed at this opportunity to pass me so easily...
Next day, mechanic came home by me,we did a VCDS scan although there were no error lights on the dash. No visible brake fluid leaks were visible either on any of the wheels the floor, or anywhere. Neither did the brake fluid level dropped. Checked the brake fluid color, and it was black like molasses!! Note that I had done a complete Brake fluid change about 2 years ago without any problem before..I checked in the engine bay for any obvious signs of BF leaks etc..We (the mechanic and I) decided to flush out and change the entire BF again without success!! Even bled the ABS pump using VCDS, and the brake pedal was still going straight to the floor without much resistance.
Checked for any vacuum leaks on the lines inside the engine bay without finding any. All this time the mechanic was telling me he already knew that the BMC rubber seals were bad and not able to seal properly, resulting in the blackish discolouration in the reservoir. The next obvious thing to do is to change the BMC,hence my original request for any advice in doing so.
Hopefully some chap in the UK or any country with RHD Q7 's may be able to offer some advice.
We'll see.
In the pic attached, the liquid in the shot glass is some of the BF from the Cylinder reservoir.
Please note that Dot 4 Brake Fluid is recommended for these vehicles.

 

Thanks for detailing how you went through that progression, and also with the travel mechanic, etc. The master cylinders are not a common failure point, so was just curious if you'd been through the 4L Q7 brake diagnostics progression, which you have. If you replacing the master cylinder, don't forget to check your rubber brake lines (at the wheels) for cracks, swelling, wear, as the rubber lines don't age well. You can get Corteco OEM replacement lines fairly cheap, etc. Just something to think about.

I've got those (new brake lines) on my parts list for next brakes replacement.

 

Thanks P,will definitely look into all avenues..barring the definite need to replace my BMC,unfortunately. All things considered, it has lasted 15 years with no problem, until recently. I know you have a 2010 Q7 als5,but it it what it is I guess..Have to get the replacement BMC ordered from Latvia as it seems to be a very difficult part to get, being for a RHD.
I did bleed all wheels in accordance to the specifications..For the newbies, each wheel has TWO bleeding nipples, so you will need to bleed 8 nipples total. And if you are on this forum and do not possess a VCDS scan tool, I suggest you do, and understand how to utilize its functionality. You will be able to save tons of money by DIY projects. As I did by just bleeding the entire brake fluid system, including the ABS pump.
But..I still await any advice on removing the defective BMC and replacing it!! Haven't seen anything on YouTube etc unfortunately..And haven't received any favorable response!! The 7 is grounded as it is as a matter of safety !!


Guess I'll have to dabble on my own.
Cheers..!!

 

I'd get the service/repair manual:

Removing – Remove plenum chamber cover ⇒ General body repairs, ex‐ terior; Rep. gr. 64 ; Flush bonded windows; Removing and installing plenum chamber cover . – Remove engine compartment seal and cover strip in vicinity of brake servo. Audi Q7 2007 ➤ Brake system - Edition 03.2019 148 Rep. gr.47 - Brakes - hydraulics © satelettronica
– Remove front panel (bulkhead) of plenum chamber.
– Place sufficient lint-free cloths in plenum chamber in vicinity of brake master cylinder.
– Draw off as much brake fluid as possible from brake fluid res‐ ervoir using brake filling and bleeding equipment - VAS 5234- .
– Unplug connector from float warning indicator sender.
– On vehicles with manual gearbox, disconnect supply hose for clutch master cylinder and seal with a plug.
– Remove brake fluid reservoir. To do this press locking tabs on reservoir outwards and simultaneously pull reservoir out of sealing plugs.
– Pull front left brake line out of retainer on brake master cylin‐ der.
– Disconnect brake lines from brake master cylinder and seal brake lines with sealing plugs - 1H0 698 311 A- from repair kit.
– Unscrew nuts ⇒ Item 10 (page 148) from brake master cylin‐ der.
– Carefully remove brake master cylinder from brake servo.

Installing:
– Installation is carried out in reverse sequence. Observe the following points when installing:
– When fitting together brake master cylinder and brake servo unit, ensure that push rod is correctly located in brake master cylinder. Seal between brake master cylinder and brake servo must be fit‐ ted. Always use new nuts ⇒ Item 10 (page 148) .
– Bleed brake system ⇒ page 141 . Basic (default) settings for brake pressure sender - G201- must be performed after bleeding brake system. Connect up -VAS 5051B- or -VAS 5052- and select function ⇒ page 25 .

(Brake Booster R&R) Ignore this otherwise, but it's here if you need it --
7.2 Removing and installing brake servo Special tools and workshop equipment required ♦ Brake filling and bleeding equipment - VAS 5234- Removing – Remove trim (driver's side) ⇒ General body repairs, interior; Rep. gr. 70 ; Dash panel; Removing and installing dash panel . Audi Q7 2007 ➤ Brake system - Edition 03.2019 7. Exploded view - brake servo / brake master cylinder 149 © satelettronica – Remove brake light switch ⇒ page 123 . – Remove bracket for brake light switch. – Separate brake pedal from brake servo ⇒ page 126 . – Remove support on mounting bracket (push rod to brake servo runs through support). – Remove plenum chamber cover ⇒ General body repairs, ex‐ terior; Rep. gr. 64 ; Flush bonded windows; Removing and installing plenum chamber cover . – Remove engine compartment seal and cover strip in vicinity of brake servo. – Remove front panel (bulkhead) of plenum chamber. – Unplug connector from float warning indicator sender. – Disconnect earth cable from earth point on body behind elec‐ tronics box, take wiring harness (running behind brake servo) out of retainer and place aside. Audi Q7 2007 ➤ Brake system - Edition 03.2019 150 Rep. gr.47 - Brakes - hydraulics © satelettronica – Take electronics box (in plenum chamber, left-side) out of re‐ tainer and place as far as possible aside ⇒ Electrical system; Rep. gr. 97 ; Removing and installing fuse holder, relay carrier, electronics boxes and control units; Removing and installing electronics box in plenum chamber (left-side) . – Place sufficient lint-free cloths in plenum chamber in vicinity of brake master cylinder. – Draw off as much brake fluid as possible from brake fluid res‐ ervoir using brake filling and bleeding equipment - VAS 5234- . – On vehicles with manual gearbox, disconnect supply hose for clutch master cylinder and seal with a plug. – Remove brake fluid reservoir. To do this press locking tabs on reservoir outwards and simultaneously pull reservoir out of sealing plugs. – Pull front left brake line out of retainer on brake master cylin‐ der. – Disconnect brake lines from brake master cylinder and seal brake lines with sealing plugs - 1H0 698 311 A- . – Unscrew nuts from brake master cylinder ⇒ Item 10 (page 148) . – Carefully remove brake master cylinder from brake servo. – Pull vacuum hose out of brake servo. – Take brake lines out of triple retainer on brake servo. – Disconnect front left brake line at connecting point in front left wheel housing. – Remove bolts from brake master cylinder ⇒ Item 11 (page 148) . – Carefully remove brake servo from plenum chamber. Installing – Installation is carried out in reverse sequence. Observe the following points when installing: Attaching brake pedal to brake servo – Hold ball head of push rod in front of mounting and push brake pedal towards brake servo so that ball head audibly locks into place. – After installing, bleed brake system ⇒ page 141 and clutch. Basic settings for brake pressure sender must be performed after bleeding brake system. Connect up -VAS 5051B- or -VAS 5052- and select function ⇒ page 25 . – Install brake light switch ⇒ page 123 . 7.3 Removing and installing potentiometer for brake servo diaphragm travel - G420- Potentiometer for brake servo diaphragm travel not installed on all models – Remove plenum chamber cover ⇒ General body repairs, ex‐ terior; Rep. gr. 64 ; Flush-bonded windows; Removing and installing plenum chamber cover . Audi Q7 2007 ➤ Brake system - Edition 03.2019 7. Exploded view - brake servo / brake master cylinder 151 © satelettronica – Take electronics box (in plenum chamber, left-side) out of re‐ tainer and place as far as possible aside ⇒ Electrical system; Rep. gr. 97 ; Removing and installing fuse holder, relay carrier, electronics boxes and control units; Removing and installing electronics box in plenum chamber (left-side) . – Unplug connector from potentiometer for diaphragm travel. – Pry snap ring out of groove -arrow- and pull potentiometer for diaphragm travel out of brake servo. Installing Installation is carried out in reverse sequence. – Plug in connector for potentiometer for diaphragm travel. – Install plenum chamber cover ⇒ General body repairs, exte‐ rior; Rep. gr. 64 ; Flush-bonded windows; Removing

 

Hey Prestige, thanks a million for that information on the subject matter!! Really really appreciate it!! I don't have the workshop manual, so that is indeed very valuable info!!! It may be a little different, being my Brake servo is on the right hand side, opposite to the electronics box with all of the fuses and relays etc inside the plenum!!..But very informative!!
The OEM replacement Brake Master Cylinder (RHD) was ordered and is coming from the Czech Republic via FedEx, so maybe by next week I should receive it..and initiate the task of removing and replacement.
Will advise how that goes!!
Thanks!! Cheers!!