Brake Fluid Flush Order Critical?

[JWebb_C7_Comp]

Hey guys,

I purchased the FCP brake fluid kit with pressure bleeder, catch bottles, etc.. And, I did the fluid swap today. Car is just over (3) years and it hadn't been done. I started at passenger rear, then driver rear, etc... That is, I intended to work from caliper farthest from reservoir to the closest. Job is done, car drives and brakes the same as it did yesterday.

That said, having just looked at the 11.2017 Maintenance manual for A6/A7 2011 forward, I'm concerned I may not have done the procedure in the right order. The manual has a table that shows expected amount of fluid to be drawn from each caliper/line. It starts with FRONT then goes to REAR.

If I did the job out of sequence, but car drives fine and fluid is between min and max after driving, could I have created any "problems"?

Worst case, I'm thinking I may have moved less of the old stuff out than I intended. Fluid at rear wheels had crud in it but it was still very light yellow --- not super dirty. But, the fronts looked like there was no crud at all.

Overall, job is easy and not worth paying dealer if you've got a little spare time on your hands.

[morski]

With the Audi it states start at front left then front right and then rear. Front need to drain 200ml each followed by 300 each at rear to a total of 1L I Dont think you will have messed anything up just maybe not drained enough for a full flush

[JWebb_C7_Comp]

With the Audi it states start at front left then front right and then rear. Front need to drain 200ml each followed by 300 each at rear to a total of 1L I Dont think you will have messed anything up just maybe not drained enough for a full flush

That’s how I read that too, but AFTER I finished. So, I probably only flushed a percentage of my system. I can always order up another liter from FCP, and do it again over the summer som time.


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[A6sport]

That’s how I read that too, but AFTER I finished. So, I probably only flushed a percentage of my system. I can always order up another liter from FCP, and do it again over the summer som time.


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Yea, but don't wait until summer. You were already a year overdue. I think it issue with older fluid is it loses its ability to keep moisture out and modulate boiling points. However, you may have gotten enough of the old stuff out?

[Dasquade]

You mind sharing the audi "official" brake drain procedure please :).

[JWebb_C7_Comp]

I got the order wrong..

The manual spans many documents and pages (available from Audi for download), but the table of interest lists the Bleed Screw Sequence and Extracted Brae Fluid Amounts per axle as follows:

Bleed Screw Sequence Fluid Volume
Driver front - 0.20 liter
Passenger front - 0.20 liter
Driver rear - 0.30 liter
Passenger rear - 0.30 liter
Clutch Slave, if applicable 0.015

*Auto trans = 1.0 Liter
* Manual = 1.15 liter

[morski]

The manual fails to tell you that you will not evacuate any old fluid form the abs pump. There is no guidance in vcds for this either. ODIS can and ive tried it on an Autel Pro machine which is also good. The abs pump needs to be told to cycle for a certain period of time whilst bleeding the appropriate caliper and having the pedal slightly depressed.

[Valpo A7]

There seems to be no set interval on when to perform a brake fluid change. The only commonality amongst manufactures is that only some of recommend it be done.

Different manufacturers require brake fluid changes at different mileage intervals. In Chevrolet models, brake fluid change is required every 45,000 miles. For Honda models, it's every three years regardless of vehicles mileage. In Volkswagens, the recommended interval is three years. Mercedes-Benz vehicles call for fresh fluid every two years or 20,000 miles. On other manufacturers, there are no recommendations for replacing brake fluid, only instructions to inspect it periodically. I have even found independent garage websites that recommend about 4 years or as needed.

If all the companies are using basically the same fluid, same lines, same components then why is it not the same across all cars? Well the answer is it depends on driving conditions and driving styles. We are all different and as such all need a different interval.

For all of my cars I am overdue by recommendations. WAY overdue but at the same time, all my brakes are in very good shape and the fluids look only slightly darkened. All of the cars in my family fleet stop just as good today as they did new. I picked up a moisture tester and last I checked all of my cars are well below the recommended max moisture content. My Jeep has 108,000 on the original brake fluid, the Audi has at least 60,000 miles on the brake fluid, and the most recent addition, my daughters Chevy Cruze is probably at 80,000 miles on the original fluid. My last 2 cars before the Audi I racked up a combined 366,000 miles between the 2 with no brake fluid changes and no problems.

In over 34 years of driving I have yet to have to replace components because the fluid went bad. I have only changed 3 wheel cylinders in that time frame. 1 was because the fitting broke off in it when changing a rotted line and the other 2 got destroyed taking off the rear drums that were seized onto the center hub. The rotted line was back in the late 1980s and was because my area uses way to much salt on the roadways in the winter time. The car was my very old 1981 Mustang so it was before the time of galvanized steel and adequate undercoating.

BUT with all this being said, you are not wrong to change fluid at whatever interval you feel you need to. And leaving a bit of old fluid in is no big deal as well.

[JWebb_C7_Comp]

There seems to be no set interval on when to perform a brake fluid change. The only commonality amongst manufactures is that only some of recommend it be done.

Different manufacturers require brake fluid changes at different mileage intervals. In Chevrolet models, brake fluid change is required every 45,000 miles. For Honda models, it's every three years regardless of vehicles mileage. In Volkswagens, the recommended interval is three years. Mercedes-Benz vehicles call for fresh fluid every two years or 20,000 miles. On other manufacturers, there are no recommendations for replacing brake fluid, only instructions to inspect it periodically. I have even found independent garage websites that recommend about 4 years or as needed.

If all the companies are using basically the same fluid, same lines, same components then why is it not the same across all cars? Well the answer is it depends on driving conditions and driving styles. We are all different and as such all need a different interval.

For all of my cars I am overdue by recommendations. WAY overdue but at the same time, all my brakes are in very good shape and the fluids look only slightly darkened. All of the cars in my family fleet stop just as good today as they did new. I picked up a moisture tester and last I checked all of my cars are well below the recommended max moisture content. My Jeep has 108,000 on the original brake fluid, the Audi has at least 60,000 miles on the brake fluid, and the most recent addition, my daughters Chevy Cruze is probably at 80,000 miles on the original fluid. My last 2 cars before the Audi I racked up a combined 366,000 miles between the 2 with no brake fluid changes and no problems.

In over 34 years of driving I have yet to have to replace components because the fluid went bad. I have only changed 3 wheel cylinders in that time frame. 1 was because the fitting broke off in it when changing a rotted line and the other 2 got destroyed taking off the rear drums that were seized onto the center hub. The rotted line was back in the late 1980s and was because my area uses way to much salt on the roadways in the winter time. The car was my very old 1981 Mustang so it was before the time of galvanized steel and adequate undercoating.

BUT with all this being said, you are not wrong to change fluid at whatever interval you feel you need to. And leaving a bit of old fluid in is no big deal as well.

Good perspective.. I had a 1978 charger that lasted well into the mid 80s and I’d be shocked.

I’ve marked the brake maintenance as completed in my personal log, though I could add an “ * “ in that it’s only “partially” done (I.E., some unknown percentage - 15% maybe - of the old stuff remains). Not losing sleep over that...






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[Alabama]

There seems to be no set interval on when to perform a brake fluid change. The only commonality amongst manufactures is that only some of recommend it be done.

Different manufacturers require brake fluid changes at different mileage intervals. In Chevrolet models, brake fluid change is required every 45,000 miles. For Honda models, it's every three years regardless of vehicles mileage. In Volkswagens, the recommended interval is three years. Mercedes-Benz vehicles call for fresh fluid every two years or 20,000 miles. On other manufacturers, there are no recommendations for replacing brake fluid, only instructions to inspect it periodically. I have even found independent garage websites that recommend about 4 years or as needed.

If all the companies are using basically the same fluid, same lines, same components then why is it not the same across all cars? Well the answer is it depends on driving conditions and driving styles. We are all different and as such all need a different interval.

Great point. Maybe a holdover from the days of more rapidly degradable rubber hoses, greater chance of damage from road debris, more salt in the winter, etc.? So you would recommend periodic inspection (say with each oil change) and testing if any concerns?

[Valpo A7]

What I recommend is follow whatever schedule you feel comfortable following. For my own use I feel confident in how I approach the brake repairs. I am simply putting out information on my experiment of 1 families worth of cars. Now if you are a short hop town driver that never really heats anything up then adjust accordingly to what you feel is needed.

Before Covid I was logging 125 miles a day round trip for just going back and forth to the office. I would put on 10,000 miles in about 110 - 120 days. Since the Audi sits more now than it gets driven I might go ahead and flush the system this summer. I drove highway and hardly touched the brakes. My last car got 125,000 miles on the front brakes and the rears were original when we traded it in at 190,000 miles.

[JWebb_C7_Comp]

What I recommend is follow whatever schedule you feel comfortable following. For my own use I feel confident in how I approach the brake repairs. I am simply putting out information on my experiment of 1 families worth of cars. Now if you are a short hop town driver that never really heats anything up then adjust accordingly to what you feel is needed.

Before Covid I was logging 125 miles a day round trip for just going back and forth to the office. I would put on 10,000 miles in about 110 - 120 days. Since the Audi sits more now than it gets driven I might go ahead and flush the system this summer. I drove highway and hardly touched the brakes. My last car got 125,000 miles on the front brakes and the rears were original when we traded it in at 190,000 miles.

If you’re decide to flush, the kit I got from FCP worked just fine, though there are certainly nicer and more expensive kits. With three cars in our “family” fleet, I’m only going to use this one or two times per year... didn’t need anything fancy.


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[akingzkid]

Other methods that I read have all said to start with the passenger rear, then driver rear, then passenger front and lastly the driver front (closest to the brake fluid reservoir). Why is this the exact opposite. Makes me think my whole life is a lie. LOL. Weird.

[JWebb_C7_Comp]

Other methods that I read have all said to start with the passenger rear, then driver rear, then passenger front and lastly the driver front (closest to the brake fluid reservoir). Why is this the exact opposite. Makes me think my whole life is a lie. LOL. Weird.

The method you described is old-school, generally accepted as working farthest from reservoir to closest. This is what I tried - wrongly - to implement.

The darned Audi sequence is different. That said, I think most of the fluid has been flushed and the job is mostly done.

I MAY shorten the next interval to make-up for my “failure.” Not too worried, however; the car stops great - even on snow tires - and I doubt the braking system is going to fail anytime soon due to lack of fluid being in perfect condition.


If this was a track car, I’d be running high temp fluid for the track season and would absolutely re-do the job.. but, it’s not..


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