Brake fluid flush, how much fluid?
03-06-2012, 07:29 AM
#1
Brake fluid flush, how much fluid?
2001 Audi A6 2.7T Quattro
Ok, so my wife is complaining that she has to press the brakes harder for the car to stop. I didn't notice any difference, but I never changed brake fluid before and I really think this is original fluid.
I want to flush the whole system, but cant find how much fluid I need in the service manual or anywhere, anyone know?
Also, I dont really want to buy a pressure bleeder, how do I do it without one, I can use my wife to press the brakes but how exactly do I/she do it then?
Ok, so my wife is complaining that she has to press the brakes harder for the car to stop. I didn't notice any difference, but I never changed brake fluid before and I really think this is original fluid.
I want to flush the whole system, but cant find how much fluid I need in the service manual or anywhere, anyone know?
Also, I dont really want to buy a pressure bleeder, how do I do it without one, I can use my wife to press the brakes but how exactly do I/she do it then?
03-06-2012, 08:49 AM
#2
1 liter should be enough.
A one liter can of Pentosin Super Dot 4 brake fluid should be enough, but you can buy two to be safe. If you can remove the reservoir, take it off, drain it and clean it out. Then re-install it and fill it with clean brake fluid. That way only clean brake fluid is now in the system going through the lines, instead of having mixed fluid. Once you see the clean fluid coming out at the bleeder screw, you know its flushed clean on that circuit.
http://www.amazon.com/Pentosin-Super.../dp/B0042G8D7U
http://www.amazon.com/Pentosin-Super.../dp/B0042G8D7U
03-06-2012, 09:07 AM
#3
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i would get a pressure bleeder. You will be happy you did in the long run. $55 for a motive.
Anyhow, work from RR to LR to RF to LF (in order of distance),
The first brake takes the most fluid - enough to run it through the caliper, line and drain the old stuff in the reservoir. I figure 300 ml for that one. The 200 ml for the LR and 150 each for the fronts.
If you do it manually, it is *IMPERATIVE* that you never have the bleeder open when the pedal is going back up. Only the constant pressure of the pedal keeps air out. So its "press honey- open-close-release honey". No deviation, except to call here "sweetie". That's allowed.
But get the motive.
use good fluid. I suggest Castrol GT-LMA. It holds up a bit longer.
Make sure you don't strip the bleeders. They can seize. To move them use a deep *6-pt* (not 12) socket. Then go back to your line wrench. You do have a line wrench, don;t you?
G
Anyhow, work from RR to LR to RF to LF (in order of distance),
The first brake takes the most fluid - enough to run it through the caliper, line and drain the old stuff in the reservoir. I figure 300 ml for that one. The 200 ml for the LR and 150 each for the fronts.
If you do it manually, it is *IMPERATIVE* that you never have the bleeder open when the pedal is going back up. Only the constant pressure of the pedal keeps air out. So its "press honey- open-close-release honey". No deviation, except to call here "sweetie". That's allowed.
But get the motive.
use good fluid. I suggest Castrol GT-LMA. It holds up a bit longer.
Make sure you don't strip the bleeders. They can seize. To move them use a deep *6-pt* (not 12) socket. Then go back to your line wrench. You do have a line wrench, don;t you?
G
03-06-2012, 09:15 AM
#4
AudiWorld Super User
A distinct change in brake pressure required to stop is not a little thing to be dismissed. It could be a cocked piston in a caliper, a worn out brake pad (although pads are in pairs, sometimes one wears out really quickly due to a problem!), a leaking hose causing loss of a caliper braking capability, etc., etc. It would be unlikely that bleeding or flushing a system would be the remedy for such a problem!!
Investigate the brake system sooner than later!
For the discussion, two liters almost surely for first time. HIghly recommend ATE Racing Blue fluid. Also comes in amber for the next time you flush. Although I've only used Blue...the color changes over time and even in a year you can tell the difference between fresh blue and old blue. Amsoil DOT4 also comes highly recommended, the specs speak for themselves. Fair disclosure....Lifetime Amsoil dealer although I haven't used Amsoil DOT4 personally...yet. Still have liters of ATE Blue which has worked extremely well for me having suffered failures of Girling master cylinders on Saabs when using Castrol LTF....
Second...buy the pressure bleeder kit at www.bavauto.com. Once you have it you'll curse yourself for not having had it 40 years earlier. It is THAT much easier. I've bled brakes for years the old fashioned way, even using a check-valve-type hose and the brake pedal...the pressure bleeder rocks!! USE a six-sided open end box wrench or flare nut wrench on those bleeders...other wrenches will round off the bleeder.
Third, I can't recommend using the brake pedal to bleed brakes except in an emergency. It takes two people (except with check-valve hose or check-valve bleeders) and runs the risk of over-travel of the master cylinder piston and seals with the result of tearing or damaging the master cylinder piston seals...especially on older cars like yours that haven't been frequently bled.
Investigate the brake system sooner than later!
For the discussion, two liters almost surely for first time. HIghly recommend ATE Racing Blue fluid. Also comes in amber for the next time you flush. Although I've only used Blue...the color changes over time and even in a year you can tell the difference between fresh blue and old blue. Amsoil DOT4 also comes highly recommended, the specs speak for themselves. Fair disclosure....Lifetime Amsoil dealer although I haven't used Amsoil DOT4 personally...yet. Still have liters of ATE Blue which has worked extremely well for me having suffered failures of Girling master cylinders on Saabs when using Castrol LTF....
Second...buy the pressure bleeder kit at www.bavauto.com. Once you have it you'll curse yourself for not having had it 40 years earlier. It is THAT much easier. I've bled brakes for years the old fashioned way, even using a check-valve-type hose and the brake pedal...the pressure bleeder rocks!! USE a six-sided open end box wrench or flare nut wrench on those bleeders...other wrenches will round off the bleeder.
Third, I can't recommend using the brake pedal to bleed brakes except in an emergency. It takes two people (except with check-valve hose or check-valve bleeders) and runs the risk of over-travel of the master cylinder piston and seals with the result of tearing or damaging the master cylinder piston seals...especially on older cars like yours that haven't been frequently bled.
Last edited by SloopJohnB@mac.com; 03-06-2012 at 10:01 AM.
03-06-2012, 09:20 AM
#5
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I'd be very careful doing it with the pedal - see this: https://www.audiworld.com/forums/sho...ht=brake+flush
As said above a pressure bleeder is well worth it.
Also, to totally flush and bleed you need to activate the ABS pump via a VAG-COM. A lot of folks (and shops) skip this and then don't know why the pedal is still somewhat mushy...
Good luck
Jim
As said above a pressure bleeder is well worth it.
Also, to totally flush and bleed you need to activate the ABS pump via a VAG-COM. A lot of folks (and shops) skip this and then don't know why the pedal is still somewhat mushy...
Good luck
Jim
03-06-2012, 09:22 AM
#6
AudiWorld Super User
i would get a pressure bleeder. You will be happy you did in the long run. $55 for a motive.
Anyhow, work from RR to LR to RF to LF (in order of distance),
The first brake takes the most fluid - enough to run it through the caliper, line and drain the old stuff in the reservoir. I figure 300 ml for that one. The 200 ml for the LR and 150 each for the fronts.
If you do it manually, it is *IMPERATIVE* that you never have the bleeder open when the pedal is going back up. Only the constant pressure of the pedal keeps air out. So its "press honey- open-close-release honey". No deviation, except to call here "sweetie". That's allowed.
But get the motive.
use good fluid. I suggest Castrol GT-LMA. It holds up a bit longer.
Make sure you don't strip the bleeders. They can seize. To move them use a deep *6-pt* (not 12) socket. Then go back to your line wrench. You do have a line wrench, don;t you?
G
Anyhow, work from RR to LR to RF to LF (in order of distance),
The first brake takes the most fluid - enough to run it through the caliper, line and drain the old stuff in the reservoir. I figure 300 ml for that one. The 200 ml for the LR and 150 each for the fronts.
If you do it manually, it is *IMPERATIVE* that you never have the bleeder open when the pedal is going back up. Only the constant pressure of the pedal keeps air out. So its "press honey- open-close-release honey". No deviation, except to call here "sweetie". That's allowed.
But get the motive.
use good fluid. I suggest Castrol GT-LMA. It holds up a bit longer.
Make sure you don't strip the bleeders. They can seize. To move them use a deep *6-pt* (not 12) socket. Then go back to your line wrench. You do have a line wrench, don;t you?
G
As I've said before, watch out for seal compatibility issues (your fluid gets black in six-9 months) with Castrol GT-LMA (it's supposed to be a Low Moisture Absorption fluid). I wouldn't even think of doing a manual brake pedal bleed on these cars with ABS anymore.
By stripping the bleeders I mean rounding off the hex head on the bleeder. That being said, it's possible to actually strip the threads on either the bleeder or the caliper....either situation can lead to having to replace the caliper. I've put a dab of anti-seize on the bleeder threads when reinserting them although you don't normally have to remove them. I only remove them if they're hard to turn after loosening or I've never removed them on a particular car and want to investigate the sealing tip for corrosion.
Last edited by SloopJohnB@mac.com; 03-06-2012 at 09:40 AM.
03-06-2012, 09:41 AM
#7
AudiWorld Super User
Agree...get the pressure bleeder.
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03-06-2012, 11:10 AM
#8
ughhh come on $55 for something that I'll only use once. This car will be gone in 2 years.
Oh and my pads are supposedly low, so thats probably why she thinks the car is not stopping as well as it used to. But I looked at the pads, there is like over 1/2inch of pad left, but the sensor wire got cut early for some reason.
Can I just be really really carefull when bleeding it? and what do you mean I need to use vag-com? In the service manual it shows 2 different abs systems, for my system it says I dont need to use vag-com.... I have the 2001 with esp... it does say if there is air in the system then I would need to use the vag-com, but it doesn't say how... which measuring blocks, or whatever, etc?? oh in the link it said measuring block 2 or something...
can I still do the vag-com bleeding even if I didn't get air into the system, just to be safe? can I do it now, before I even bleed the system to see if it improves with the original fluid?
Oh and my pads are supposedly low, so thats probably why she thinks the car is not stopping as well as it used to. But I looked at the pads, there is like over 1/2inch of pad left, but the sensor wire got cut early for some reason.
Can I just be really really carefull when bleeding it? and what do you mean I need to use vag-com? In the service manual it shows 2 different abs systems, for my system it says I dont need to use vag-com.... I have the 2001 with esp... it does say if there is air in the system then I would need to use the vag-com, but it doesn't say how... which measuring blocks, or whatever, etc?? oh in the link it said measuring block 2 or something...
can I still do the vag-com bleeding even if I didn't get air into the system, just to be safe? can I do it now, before I even bleed the system to see if it improves with the original fluid?
Last edited by badinstincts; 03-06-2012 at 11:33 AM.
03-06-2012, 11:46 AM
#9
Just to be clear is the pedal mushy or require more force?
If the pedal is mushy with longer pedal travel to get the car to stop then there is air in the system and needs to be bleed. If the pedal is hard and requires more force to get the car to stop(pedal travel same or less than before) then it is something else like booster problem or mechanical problem. Bleeding will most likely not help.
The power bleeder will work on other cars as well, but if you don't want to get one then you can do it the old fashion way with the pedal and a good helper. Get some ATE super blue racing fluid, since your fluid is probably gold or clear. Use a turkey baster to suck the old fluid out of the reservoir and refill with new blue fluid. Put a 2x4 piece of wood under the brake pedal in a position that won't let the pedal go all the way to the floor. This helps protect from over extending the pedal travel and damaging seals. Go about the bleeding procedure until you get the blue fluid at each corner. Be careful to not let the reservoir ever run out of fluid.
If the pedal is mushy with longer pedal travel to get the car to stop then there is air in the system and needs to be bleed. If the pedal is hard and requires more force to get the car to stop(pedal travel same or less than before) then it is something else like booster problem or mechanical problem. Bleeding will most likely not help.
The power bleeder will work on other cars as well, but if you don't want to get one then you can do it the old fashion way with the pedal and a good helper. Get some ATE super blue racing fluid, since your fluid is probably gold or clear. Use a turkey baster to suck the old fluid out of the reservoir and refill with new blue fluid. Put a 2x4 piece of wood under the brake pedal in a position that won't let the pedal go all the way to the floor. This helps protect from over extending the pedal travel and damaging seals. Go about the bleeding procedure until you get the blue fluid at each corner. Be careful to not let the reservoir ever run out of fluid.
03-06-2012, 11:49 AM
#10
AudiWorld Super User
FWIW, I've not used vag-com to bleed the systems on either of my audi V8s...2K and 02 models. So yes, you don't need to unless you get air in the system by emptying the reservoir.
And like other people and I've said before, yes you can do it the hard way, but the downside is you eff up the master cylinder. You pays (or not) your moneys and takes your choices.
Unless you're like 75 years old and never intend to bleed another car's brakes again, buy the pressure bleeder.
Virtually every car on the road in North America needs to have it's brakes flushed biannually; annually in mountain country or if tracked. If you have the dealer do it it will cost you more than the bavauto kit. This should not be the last car you'll ever need to bleed the brakes.
How would she know the pads are low unless someone told her and she's over thinking something she's not qualified to think about, period? In any case, low pads wouldn't give increased braking effort per se.
And like other people and I've said before, yes you can do it the hard way, but the downside is you eff up the master cylinder. You pays (or not) your moneys and takes your choices.
Unless you're like 75 years old and never intend to bleed another car's brakes again, buy the pressure bleeder.
Virtually every car on the road in North America needs to have it's brakes flushed biannually; annually in mountain country or if tracked. If you have the dealer do it it will cost you more than the bavauto kit. This should not be the last car you'll ever need to bleed the brakes.
How would she know the pads are low unless someone told her and she's over thinking something she's not qualified to think about, period? In any case, low pads wouldn't give increased braking effort per se.
