Hydraulic Problems UPDATE [Archive] - Audi Forums

: Hydraulic Problems UPDATE

03-18-2011, 08:28 PM
Car: Audi 90 quattro 20V

So I changed the high pressure hydraulic hose as described here: https://www.audi-forums.com/audi-80-90-coupe-forum/59402-high-pressure-hydraulic-hose-removal.html

The problem now is that the power steering feels like it has absolutely no assist. The brakes are sometimes hard at first, and then give and have assist. The brake light (dash light) comes on each time the brakes are pressed. I fixed my handbrake by attaching a spring to the brake pad, but I don't think that caused any of those problems.

Do you think there is air trapped somewhere? Is the hydraulic pressure accumulator bad? Servo? Pump? The belt is turning fine. Thanks for the advice!


03-18-2011, 11:30 PM
Hey Trop...bingo man....you got air trapped in there somehow. Bleed the brakes 3-4 times each wheel starting from the RR..LR..RF..LF and see if most of the air escapes. There might be air in the hydraulic system via the power steering servo aswell but this I have never had a problem with so I'm not to sure where to bleed in that regard...LOL first time I'm stumped. Good luck and post back or e-mail me! Cheers!

03-19-2011, 01:16 AM
I'm gonna try to tackle these problems in the morning. When we reinstalled the hydraulic hose, we didn't fill it with hydraulic oil first. I thought it would purge itself through the reservoir somehow. I'm not very familiar with how these systems work, so that could be wrong. I'm thinking we'll probably end up taking at least one end of that hose back off and seeing if it has oil in it. If not, fill it up and reattach to see if that fixes it. If that doesn't fix it, we'll just read in the Chilton's manual and go from there. Hopefully we can figure it out.

As for the brakes, what's the best way to bleed all 4 brakes without the car in the air? I've never actually had to bleed the entire brake system before.

One other issue: as far as I can tell, the rear diff lock doesn't work. The "ABS Off" light comes on after a short distance and I am unable to turn the ABS on and off with the switch before and after that. Likewise, the diff lock switch doesn't appear to do anything. Could this be related to the hydraulic system and/or the brake problem?

I think this car sat far longer than the seller let on or maybe more than he knew. I changed the air filter today and it was immediately apparent that the kid never touched the car other than to drive it. The filter was filthy and full of seed junk, and the airbox had two or three handfuls of old dried up seed shells just laying around in there. Ridiculous. If I had known it was that bad, I would have changed it much sooner, but I still had to wait for the filter since none of the parts stores had it.