Hello,

To start: 1999 Audi A4 1.8T Quattro
150k, AEB,DTV Tip Tronic

Alright so i just replaced all my front end control arms. I zip tied the calipers up, didn't let them hang. On my way back home from the car wash my brakes went all the way to the floor. I jacked it up in the front and saw the front rubber line going from the wheel well to the caliper was split. So i replaced both front hoses and at this point the master cylinder was bone dry no fluid from the leak. I bought a new master cylinder a week before this happened. So i figured at this point i would replace it, which I did today. I tried bleeding the brakes and get nothing. No pressure at all. I did loosen the hex bolts as well as the two nuts on the master clyinder and booster. I have no brakes at all, can't get any pressure to build up. Is there an adjustment i had to do with the push rod or do i need to bench bleed the master cylinder? I have replaced 4 master cylinders on different cars and this is the first time i have ran into this problem. I have searched the web, asked some friends and checked my chilton and bentley manual. I also have a Vag Com cable, so if i have to cycle the abs as some say? Any help or tips would be greatly appreciated! I been without a car for the last 3 days. I ordered the master cylinder through Fcpgroton. It said it would fit my car for sure. I saw the marking at the end of the new master cylinder was 25. My benley manual indicates something about a 23 marking and 23.33 size end on the master cylinder. Which the old master cylinder i replaced had a 23 marking at the end. Does this mean it is a incorrect size or since it fit and bolted up its fine. I also did have the new rubber oring on the master when it was installed.

Thanks, and please any thoughts or if more information will help let me know. Or if there is a way i can test to see what might be causing this. All the lines are good and there is no leaks.

 

Did you bleed the master cylinder before installing it? If not it will have to be done first before going any further.

 

Thanks for the reply! I did not bench bleed the master.. i guess i didnt know the right way of doing so and everytime i have replaced a master cylinder i never have had to. Anyone know the steps to doing so? Would that make me not have brakes at all and not be able to get pressure in the lines?

Thanks!

 

air in the system will make you not have brakes, or at least very very shitty spongy brakes. air is compressible, where as fluid is not. so all the fluid pressure going into the brake system is getting absorbed by air bubbles being compressed in the lines.

they make a kit to bench bleed them. theyre pretty cheap and its really easy. if you have enough room you may even be able to do it in the car. but the kit consists of a few plastic fittings that thread into where the brake lines normally would on the master. then you just run some hose from the fitting back into the resevoir and actuate the master cyl in and out, keeping an eye on the fluid level of course. if it runs low and sucks in air then you are back to square one. but this process takes the fluid and air trapped into the master and dumps it back into the resevoir. air bubbles to the top and out the resevoir, and nice air-less fluid goes back into the master. it may sound confusing, but its easy as hell. hope this helps.

 

Please help! We just bought our daughter a 1995 Audi A6 quattro, 2.8, with 78K miles on it. Two weeks after getting it, she complained that her a/c stops working while she's driving it. Then suddenly she calls crying saying it's overheating on her. We tow it home and begin the process of finding out why. After several days, we noticed that the fans aren't kicking on. So we jump the fan switch and all works good. So my husband so far has replaced the thermostat and the temp switch. But it's not working. When you turn on the a/c, both fans kick on. Without the a/c on, neither fan is working. Fuses have all checked out ok. Since fans do run with a/c on, can't be the fan motors or relays or fuses. Any one have any suggestions? no leaks either. when it overheats, it comes out the coolant bucket. Could really use some help! We want to get our sixteen year old back into her car and out of ours!