# Mk3 TT/TTS Brake Fluid Change How-To with Photos



## macaddict111 (Jun 13, 2018)

Hello fellow TT owners, greetings from sunny Los Angeles, California! I'm hoping this How-To finds you loving your TT and ready to save some serious money on an easy, frequent maintenance task. Today I'm going to show you how I recently changed the brake fluid on my 2017 TTS. This guide applies to any Mk3 TT or TTS. I'm not familiar with the TTRS brake system, but it should be similar.

Brake fluid absorbs moisture and degrades over time, and can develop gas, which can "mushy" the brake response. If you've read your Maintenance Schedule, you already know that Audi requires a brake fluid change every two years regardless of mileage. This is new to me, as every car I've owned before had either permanent or long-life brake fluid. My two year mark came up, and my dealer quoted me $275 for this service. The only parts I had to order for this were $40 of DOT 4 brake fluid and some tubing from Amazon, and I used parts from the trunk of my TTS and my kitchen. It couldn't have been easier.

Before we start, I prepared myself by reading through the maintenance section of the Audi repair manual. I got this by paying $30 for 24 hours access to erWin, and you get maybe 20 VIN-specific PDF OEM service procedures. I can't post them here because they're copyrighted, but it's worth the money. The procedure is in D4B8053415F - Maintenance.pdf, Section 3.13 "Brake Fluid - Changing".

Audi's shop method uses a "Pressure Bleeder" that forces brake fluid under light pressure into the reservoir from the top. This pushes new fluid down through the lines and out the bleeder in a quick manner. My goal was to buy as little new equipment as possible as I rarely do this, so I chose the Gravity method, which is the exact same thing, but much slower. This involves allowing the fluid to drain slowly on it's own, just with the force of gravity. *I do not recommend the vacuum method.* I attempted it first with this car, and it didn't work. As soon as the bleeder is loosened, it lets in air to the line and very little fluid pulls out.

Also, I have a DSG/automatic TTS. The clutch in the manual-transmission TT's shares fluid with the brake system. I have not researched these additional clutch-fluid steps, so manual owners, you're on your own.

*Supplies I used:*








· 4 X 12 oz (354 mL) Castrol DOT 4 Synthetic Brake Fluid
· About 3 feet of 1/4" Inner Diameter, 3/8" outer diameter clear PVC tubing, cut to taste
· 2 X 500 mL measuring cups, one for new fluid, one for old (you will not be able to see a change in fluid color)
· 11 mm socket wrench, with extender for the bleeders
· Tire Iron and Jack, from Trunk kit
· Lots of Paper Towels or Rags
· Rubber Gloves, for skin protection
· *A suction device*, to vacuum old fluid from the reservoir. I used my oil extractor, which runs manually or on shop air. My other idea is the spray-gun top from a spray bottle, where you could dip the straw into the bottom of the reservoir screen and spray into a container.

*Scary Warnings
· Brake fluid is hazardous to eyes, skin, and auto paint! It's a corrosive, glycol-based hydraulic fluid, not motor oil. Do not get brake fluid on yourself or on your paint. Use gloves and eye protection.
· Do not allow air to enter the braking hydraulic system, simply keep the top reservoir full of fluid while draining at all times!* Getting air into your brake lines will make them mushy and practically useless, and will require another fluid drain and bleed. *Getting air into the ABS hydraulic modulator will require a VCDS/diagnostic unit or trip to the dealer to purge the ABS valves of air.*
· *Keep the vehicle's key outside the car!*This prevents you from accidentally starting it during the process, leading to crazy/who-knows-what results.

Now that that's over, this was the easiest thing I've ever done to a car, don't worry. If you can take your wheel off and do an oil change, you can change your brake fluid.

*Step 1: Photo/mark/memorize the level of old brake fluid*

This depends on the age of the car and wear of the brake pads. Use something to mark where you should refill to.

*Step 2: Vacuum out the Old Fluid from the Brake Reservoir*
















-Remove as much old brake fluid from the reservoir as Audi's yellow strainer will allow. The OEM manual says to use the suction device to remove brake fluid to the level of the bottom of the yellow screen, if equipped. I used my extractor to get fluid out, and it always settled to about the middle of the bottom (narrow) half of the screen, so that's where I stopped. This leads to a fluid level in the reservoir at about the bottom of the wide portion of the bottle shown at the red mark on the photo below (hard to see without backlight). If you don't have a strainer equipped, vacuum to the bottom mark of the bottle as shown and don't go below. It's helpful to shine light at the back of the bottle and tap it to see the fluid level.








Don't try to take the screen out or vacuum below this level. We want a minimum of fluid in the reservoir at all times to keep air from pulling in, even if it's old.

*Step 3: Add more fluid to the Reservoir!*
If the reservoir is at the line shown in red above, it should be able to accept exactly 250 mL of new brake fluid before it reaches the Max line. Put a clean funnel into the reservoir opening, and slowly fill with 250 mL of brake fluid from the clean/new measuring cup.

You will not be able to see when you have new fluid coming out based on the color. It drains too slowly and mixes too much in the tube. You must measure to get enough new fluid through all the lines. Alternating with a different-color brake fluid is also not advised. At least in the US, all DOT4 fluid should be light yellow.

Audi's TT repair manual says to change the fluid in the following wheel order, and to remove this amount of fluid for each wheel:
1. Front Driver's Side: 200 mL
2. Front Passenger's Side: 200 mL
3. Rear Driver's Side: 300 mL
4. Rear Passenger's Side: 300 mL

*Step 4: Remove each wheel, and Drain Fluid, keeping reservoir above "Min"*- Jack up the car for each wheel according to the manual, starting with Driver's Front.

*If you have a TTS (and RS but no experience),* you have a dual-piston brake caliper! It has a crossover line underneath between the inside and outside pistons. The manual says to bleed the inside first, but does not specify how much to drain between the inside and outside calipers. So, I chose to bleed 175 mL from the inside bleeder, and 75 mL from the outside, for a total of 250 mL for the front two wheels. I still had plenty of fluid with 4 X 12 oz bottles.
*If you have a base TT,* you will have one bleeder on the fronts. Bleed 200 mL from the front bleeders.

-If you have 2 bleeders for the wheel, start with the inside bleeder. Remove the rubber bleeder cap. Use an 11 mm socket wrench with extension to loosen the bleeder (outer bleeder shown below, inner/rear same):








-Crack open the bleeder gently with the wrench. Do not rotate the wrench any more than you need to get it loose, or fluid will weep out (about 1/4 turn).
-Shove the 1/4" X 3/8" tubing all the way down the bleeder stem, and rest the bottom end of the tubing into the dirty measuring cup on the floor, as shown below.

Inside bleeder photo:








Outside Photo (behind the wheel):







-Twist the bleeder and attached tube counter-clockwise, about 1/4 to 1/2 turn, until fluid comes into the line steadily. Make sure you keep the bottom of the tube in the measuring cup and away from paint! Twist the bleeder open enough that the fluid comes out through the tube consistently, but not so much that the bleeder starts to weep fluid at its base. Clean up weeping fluid by dabbing with a paper towel. The fluid will drip slowly into the dirty/floor measuring cup. It was about the pace of a hospital IV. In my experience, it took about an hour for each 250 mL to drain. Be patient! Don't worry, I got brake fluid all over my red calipers and it didn't do anything to the paint, just my experience.
-*While watching the fluid level coming out into the measuring cup, make sure the reservoir is above the minimum line!* If the fluid starts to get low, add to it slowly, up to the max line. Have a beer, but keep a close eye on the reservoir level!







-When you have measured enough fluid drained into your floor/dirty measuring cup, turn the bleeder and attached tubing clockwise until it stops.
-Bend the tubing downward to drain as much fluid into your floor measuring cup as possible.
-Have towels ready, and slowly pull off the tubing from the bleeder. Let all the fluid drain into the cup.
-Final-tighten the bleeder clockwise with the 11 mm wrench. Audi specifies a torque here, but it's not rocket science&#8230;
-Replace the rubber bleeder cap(s)
-With a towel, dab away all fluid around the bleeder and wherever else it got.
-Replace the wheel, drain your dirty measuring cup and get it ready for the next wheel.
-Repeat Step 3 for the next wheel.
-*Don't let the reservoir go below Min! Keep checking and tapping it with backlight to see the fluid level.*

*Step 5: Refill the Reservoir to the Starting Level*
You've bled fluid from all four wheels, cleaned everything up, tightened the bleeders, and put the wheels back on.
-Refill the Reservoir with brake fluid to the same level you marked or photo'ed at the start.
-Replace the Reservoir cap and double-check all bleeders and bleeder caps.

*Step 6: Test it!*
-Start your TT and fully depress the brake pedal several times. Look for error lights. Check the fluid level again.
-Slowly drive the TT, making sure the brakes handle as expected. If not, bleed the brakes again.
-Make sure to complete at least one ABS (mash the brakes) maneuver, to ensure the ABS hydraulic modulator is happy and doesn't throw any codes.

*Results:*
Congrats! You just changed your brake fluid for about $40! This method gave me brakes exactly like I had before. I hope it works as well for you.


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## leopard (May 1, 2015)

Excellent article !

Although for what it's worth I prefer to use DOT 5.1


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## macaddict111 (Jun 13, 2018)

Please don't do that or post advice that could void people's warranties. It's a completely different type of fluid and isn't compatible. It's not a new and improved DOT 4.


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## brittan (May 18, 2007)

That's an excellent How-To. Well written and with good pictures.

Two comments, if I may:

1. An alternative to using a vacuum extractor to remove the fluid from the reservoir is a simple 100ml plastic syringe and a short length of plastic tube. Cheap and disposable. Also useful if you need to remove some fluid when fitting new brake pads.

2. I can see you are working on a firm level surface but some back-up for the jack is always a good idea. Simple wood blocks are enough.


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## phazer (Apr 2, 2018)

Nice write up for the doing. Personally I use an EaziBleed (£20), no fuss or mess, takes no time at all.


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## macaddict111 (Jun 13, 2018)

brittan said:


> An alternative to using a vacuum extractor to remove the fluid from the reservoir is a simple 100ml plastic syringe and a short length of plastic tube.


That's a great idea! Thanks for the contribution.


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## leopard (May 1, 2015)

macaddict111 said:


> Please don't do that or post advice that could void people's warranties. It's a completely different type of fluid and isn't compatible. It's not a new and improved DOT 4.


No it isn't ! And yes it is an improved DOT 4 and is compatible

Get your facts in order :roll:


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## phazer (Apr 2, 2018)

leopard said:


> macaddict111 said:
> 
> 
> > Please don't do that or post advice that could void people's warranties. It's a completely different type of fluid and isn't compatible. It's not a new and improved DOT 4.
> ...


^^He's right. DOT 5.1 is glycol based, compatible with DOT 4 but has a lower water content and higher boiling point. It's designed for higher performance cars.

The one that is frequently sited as do not use is DOT 5 - this is entirely synthetic and hydrophobic. It must not be mixed with a glycol based fluid.


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## macaddict111 (Jun 13, 2018)

leopard said:


> No it isn't ! And yes it is an improved DOT 4 and is compatible
> 
> Get your facts in order :roll:


Then sorry for the misunderstanding, and go ahead and write your own how-to, showing people how to *upgrade/convert* their fluid to a different one than called out by Audi, which also warns them of the difference, potential warranty non-compliance (if any), and not to fill with DOT 5.0 (which is an easy mistake that I just made reading your post). My goal is to show people how to do the same service Audi would have charged an arm/leg for with the same fluid, not speculate on non-OEM upgrades.


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## Omychron (Sep 9, 2016)

phazer said:


> ^^He's right. DOT 5.1 is glycol based, compatible with DOT 4 but has a lower water content and higher boiling point. It's designed for higher performance cars.
> 
> The one that is frequently sited as do not use is DOT 5 - this is entirely synthetic and hydrophobic. It must not be mixed with a glycol based fluid.


This is all on paper. Dot 5.1 just has higher "minimum requirements" to get the label.

I researched which fluid to use, turns out some high quality DOT4 braking fluid has higher boiling points (dry and/or wet) than DOT5.1!
http://trackdays.ie/best-racing-brake-fluid/ for example claim Castrol SRF Racing wipes the floor with basically any DOT5.1, and it "only" has a DOT4 rating. (Which is why I use it)


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## phazer (Apr 2, 2018)

Omychron said:


> phazer said:
> 
> 
> > ^^He's right. DOT 5.1 is glycol based, compatible with DOT 4 but has a lower water content and higher boiling point. It's designed for higher performance cars.
> ...


I'm absolutely aware of this and was not the point I was making :wink:

EBC also do a higher grade DOT 4 instead of producing a DOT 5.1. The important part of my post was the correction of an allegation of offering unsafe advice. As ever, if you don't know what you're doing don't touch the braking system.


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## Omychron (Sep 9, 2016)

phazer said:


> As ever, if you don't know what you're doing don't touch the braking system.


Agreed!

(Then again, brake systems are relatively easy to learn, and a good way to start maintaining your own car IMO)


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## leopard (May 1, 2015)

macaddict111 said:


> leopard said:
> 
> 
> > No it isn't ! And yes it is an improved DOT 4 and is compatible
> ...


Firstly get yourself a pair of spectacles if you think that 5.1 looks like 5.

Secondly I don't need a lesson in non compliance/ warranty when you've demonstrated this quite clearly by DIY on your own car by not getting a service log for the brakes.It doesn't matter how competent and savvy you are by saving a few bucks,you'll still have a buyer's nagging doubt whether they've been done to a high standard.
What you've scrimped on the front end,you'll lose on the back come sale time...Each to his own.

There is no speculation,DOT 5.1 is compatible and is something I prefer to use,a simple fact that I commented about after your article.

Thirdly,try not to act like some butt hurt kid when you've stated something wrongly,it doesn't look good.


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## phazer (Apr 2, 2018)

Omychron said:


> phazer said:
> 
> 
> > As ever, if you don't know what you're doing don't touch the braking system.
> ...


Yes, funnily enough my first foray into car maintenance (many years ago lol) was to change discs/pads. Piece of cake, the rest as they say....


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## macaddict111 (Jun 13, 2018)

leopard said:


> Firstly get yourself a pair of spectacles if you think that 5.1 looks like 5.
> 
> Secondly I don't need a lesson in non compliance/ warranty when you've demonstrated this quite clearly by DIY on your own car by not getting a service log for the brakes.It doesn't matter how competent and savvy you are by saving a few bucks,you'll still have a buyer's nagging doubt whether they've been done to a high standard.
> What you've scrimped on the front end,you'll lose on the back come sale time...Each to his own.
> ...


You have to use the space-bar after periods and commas.


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## phazer (Apr 2, 2018)

Wow, talk about over reaction. You do know that a forum is for opinions right? and that opinions are like arseholes, everyone has one. Perhaps the internet is not for you?


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## macaddict111 (Jun 13, 2018)

Alright alright it's back. And yes, do yourself a favor and get a pressure bleeder.


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## phazer (Apr 2, 2018)

macaddict111 said:


> Alright alright it's back. And yes, do yourself a favor and get a pressure bleeder.


Good man 8)


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## brittan (May 18, 2007)

macaddict111 said:


> Alright alright it's back. And yes, do yourself a favor and get a pressure bleeder.


 [smiley=thumbsup.gif]

I have a pressure bleeder - but it languishes in a drawer as I don't particularly like using it.


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## kevin#34 (Jan 8, 2019)

want me too, change the brake fluid, it is the one used at factory "just" 22 months ago (not so old but neither so fresh) because after the last track day, the first brake pedal push feeling is now a bit spongy&#8230; probably because I suffered from some vapour-lock....

my questions are:
- any reason for removing the old fluid from its tank, instead of from the calipers as usual?
- after fluid has been replaced, any VCDS activity is required? (in my old S3 elsawin were requiring to access to ABS channel in order to move ABS pump pistons and bleed eventual air from ABS pump)


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## macaddict111 (Jun 13, 2018)

kevin#34 said:


> my questions are:
> - any reason for removing the old fluid from its tank, instead of from the calipers as usual?
> - after fluid has been replaced, any VCDS activity is required? (in my old S3 elsawin were requiring to access to ABS channel in order to move ABS pump pistons and bleed eventual air from ABS pump)


Hey Kevin

-The old fluid in the tank is just as stale as the fluid in the lines, so you want to have as little as possible in the tank when you pull fluid down through the system. You'll always have a bit but it minimizes the amount of draining you have to do through the line and gets to fresh fluid faster.
-As long as you pay attention and don't let the reservoir go empty while bleeding, there will never be any air introduced to the system. The VCDS ABS purge is only necessary if improper bleeding was done and air was pulled into the hydraulic modulator through an empty tank.


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## kevin#34 (Jan 8, 2019)

ok, thanks, I am quite experienced in brake fluid replacement (done personally dozens of times on my motorcycles and cars) so I can easily avoid to go empty while bleeding, but I prefer to work from calipers, doesn't matter if I will need waste some more new fluid...
regarding purge trough VCDS, as I said, in my previous S3 it was required as std task after each brake fluid change as mentioned in the elsawin procedure, so I was asking if necessary on TT Mk3 too (I understand from your reply that it's not)


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