Brake/Clutch fluid flush

[Mikewire]

I haven't messed with ABS brakes before, so I'm wondering if there is anything I need to do to fully flush the brake system. I have a power bleeder and I figure that will do most of the work. The clutch is also tied into the hydro system too...any tips or suggestions from you guys?

I assume it's the same procedure as with non-abs: Start with the furthest caliper and work forward to the closest.

Anyone with a DIY?

[Roadhog]

Well you don't need the power bleeder since its useless...

siphon out the old fluid out of the res.

Fill it up with new, then bleed the master and slave for the clutch...

Fill it up again, now this is the tricky part, the ABS will have to be cycled after you bleed the brakes. This can be done by going out and standing on the brakes a bunch, or in vag com and using that to cycle the valves... Then you have to bleed the brake system again to get out the fluid that was stuck in the abs system...

Have fun, its a Pain in the ass..

[ValveFloat]

I haven't messed with ABS brakes before, so I'm wondering if there is anything I need to do to fully flush the brake system. I have a power bleeder and I figure that will do most of the work.

Is the power bleeder a thing that sucks the fluid at the bleeder or pressurizes the reservoir?
If its a sucker, don't use it. I haven't used a pressure bleeder, but they are supposed to work well.
I do it the old fashioned way, with one twist. I have a bottle with about 2 feet of clear hose on it. I connect to the bleeder valve, have someone put pressure on the pedal, open the valve, and then the helper pumps until I see new fluid, or until I need to refill the reservoir. Once I am happy, new fluid and no bubbles, I close the bleeder while the helper is on a down stroke. As long as no air is introduced (running the reservoir dry for example) I have never had to cycle the ABS pump.

I assume it's the same procedure as with non-abs: Start with the furthest caliper and work forward to the closest.

I have been told to start with the closest caliper on these cars, although no-one has been able to explain why.

I have never done my clutch.

siphon out the old fluid out of the res

That is a good idea. I have a sringe somewhere I could use to get most of the old fluid out with, I am going to try that next time.

BTW, I flush and bleed my brakes about 4 times a year.

[Mikewire]

Hmmm well I don't agree about the bleeder - it's listed as a tool in the repair manual. According to those instructions you basically you pump the new in and bleed the old at the same time and pump the clutch pedal a few times to get the new stuff in the clutch cylinders - easy I guess.

The procedure for the brakes is basically the same as above, (and also lists the bleeder as a tool to use) except the manual says to make the ABS cycle once when done and don't go over 14.5psi. I am changing to super blue DOT4 fluid so I expect to cycle it a few times to purge the old stuff out. I didn't know if the ABS valves are open or closed by default. I still like your idea of running Vag-Com to cycle the ABS. Maybe a combination of bleeding and cycling the ABS would flush it out efficiently?

I got two cans (1L each) of super blue - thats should be enough huh?

[Mikewire]

Thanks Joe, this is the pressurized power bleeder, not the extractor. Nice thing is that I can use it on my truck and other vehicles too. Oh and yes I got the bottle kit that comes with two big bottles and hose to hook to the calipers when bleeding. It's supposed to be a "one man" bleeding setup I guess.

With the order of calipers I have heard that its from the furthest to the closest and in the manual it states:
Bleeding Sequence
Right rear caliper
Left rear caliper
Right front caliper
Left front caliper

Also reading more into it:
Bleeding the brake system on vehicles with ABS is the same as for vehicles with a conventional brake system with the exception of using function 04 to bleed systems that have been completely empty.
On vehicles with a brake pressure regulator, move the regulator lever when bleeding rear brakes.

Edit: WTF is the brake pressure regulator?

I take that as exactly what you guys were saying - it's pretty much the same. I'll need to look into the function 04 thing.

Thanks guys! Anyone else with input would be appreciated.

[ValveFloat]

WTF is the brake pressure regulator?

Am just guessing here, but some older cars have a proportioning valve between the MC and the rear brakes. It has a lever on it, so the proportioning changes with rear suspension travel.
That could be what they are refering to...

[Roadhog]

The brake pressure regulator is the thing on the rear axle that regulates the braking force to the rear. If you try to bleed the rear breaks with the rear wheels off the ground you wont get any fluid flow.. You either have to disconnect it, or leave the car on the ground.

Do it the old fashioned way.. W/O the bleeder... No risk in blowing up your brake fluid res the old fashioned way. The pressure bleeders only help a lot if the system was completely dry.

And cycling the ABS pump will not do anything. The valves have to be toggled in vag com or by driving it. The pump just pressurizes the system.

[Mikewire]

Cool - thanks for all the input. That'll help when it's time to rip into it.

[Rennwagen1]

Brake pressure reg changes the amount of braking done in the rear in regards to how much wieght is added to the trunk. I.e. no wieght, normal braking. 300 lbs of luggage = more braking force needed to make the car come to a normal controlled stop. The braking force is decided by where the rear axle is sitting in regards to how much wieght in the trunk, the more wieght, the more near or past horizontal the rear beam is.

[kompressorgolf]

techs at vw and myself have used a vacuum bleeder and never an issue ive always started with the farthest brake from the cylinder. longer lines can hold more bubbles????