Audi power steering/hydraulic system - pete t
Hoping someone out there in the backroom has been here before.....

Have an ols coupe with the combined power steering and central hydraulics system (aids the brake servo). Yesterday I drained the system in order to remove a bit of it and get to something else. Re-filled the system, bled it and checked as per Haynes manual, all seemed OK.

But it's not. The auto-check system displays the symbol indicating a problem with the system (low fluid level or lack of pressure), and the pump makes a bit of noise that wasn't there before. If the steering is moved (engine running) it also makes an unpleasantly painful noise.

My assumption is that the system is failing to build up pressure as it should, but I don't know why. Any ideas/similar tales of woe (with happy, inexpensive endings) appreciated.

Audi power steering/hydraulic system - pete t
Brief update; there no longer appears to be a problem with the hydraulic system (the self check thing doesn't think there is anyway) but the steering is still making an awful noise. Any time the steering wheel is turned to any degree, I get an awful groaning (coming from the power steering pump?). Its very un-nerving, as sounds both painful and expensive. So i'm still seeking words of advice/experience. I've never had power steering on a car before (or power anything really) and I am starting to think changing up from a nice simple Sierra was a bad idea.
Audi power steering/hydraulic system - IanW3
I have a 1991 A90/20v with I think the same combined PS/brake pump (7A engine?).

The groaning noise is associated with air in the hydraulic system. The 'approved' solution is to bleed it by:
1. Top up fluid to 'MAX'
2. With vehicle jacked up & engine off, turn steering wheel sharply from lock to lock several times to let air escape.
3. Top up fluid to MAX
4. Start engine & idle for 2 mins. with wheels straight ahead
5. Watch fluid level
6. As soon as there are no rising bubbles in the reservoir, turn engine off & immediately check fluid level - top up to MAX.

To check for leaks:
Turn steering wheel to full lock in each direction & hold briefly for max pressure to build up.
With steering at full lock check rotary piston piston valve, steering rack seal, pump, hose connections.

Instructions above are abridged from 'Bentley' ISBN 0-8376-0368-4. A worthwhile buy if you are going to do any work yourself.

Also, see, esp.

Rather than using 'Pentosin', I use only Audi 'G002000' for the fluid. Capacity is 1.9 litres.

Also, consider joining - they can get Bentley manuals at a discount.

I recently added Forte PS fluid to mine - it's seems smoother, but that's probably only 'cos I spent UKP13 on it.

Here endeth today's sermon!

Audi power steering/hydraulic system - pete t
Hi Ian, thanks for the response.

Yes, it is a 7A engine. The Haynes manual I have also goes through the same sort of deal for bleeding the system (which I've done) and checking the level (also done). Tried it again today with the aid of an assistant peering at the reservoir whilst I twirled the wheel - appeared to force more air out of the system anyway. Once no more bubbles coming out, checked the level again, all looked promising. But with the engine running the system (maybe just the pump?) still makes a bit of noise - that groaning sound. Are they slightly noisy anyway or am I just paranoid?
Audi power steering/hydraulic system - Richard Hall
I hardly dare respond to this post since I know exactly which car Pete is referring to - my old 20V.... After I changed the power steering fluid, the system made groaning noises on full lock for a few days. Just as I was starting to think I had somehow damaged the steering rack, the noises vanished. I suspect small air bubbles get trapped in the system, in places where they cannot easily escape.

Richard Hall
Audi power steering/hydraulic system - IanW3
Hi Pete,
Small world.
I presume that the pressure test showed up no leaks? In which case, I feel inclined to agree with Richard.
If the problem persists, I suggest a post on Series 3/Coupe forum. Someone with more experience is bound to respond.
Richard - I have yet to take your advice about dismantling the front suspension struts. A complete engine re-build took priority, but now it\'s run in it\'s a real joy to drive. Possibly a suspension re-build over Easter.
Audi power steering/hydraulic system - IanW3
Meant to add that the only two causes of noise I've met are groaning from air in the fluid, and a whining from over tighening that 13 mm bolt that tensions the belt.
Audi power steering/hydraulic system - pete t
Hi Ian and Richard
Fantastic, thanks, feel somewhat reassured with those replies. I think I'd agree with Richard about little pockets getting trapped in funny places in the system - noticed something along those lines whilst trying to bleed it again this morning.
For the moment I will live with my paranoia, keep an eye on the reservoir and wait for it to sort itself out.
I think the noise must be air in the system as all I did was drain it (to remove one of the pipes to gain access to the thermostat - changing that has sorted out the temperature gauge too Richard) and refill; haven't moved the pump or the belt at all. But only 'cos it wasn't in the way of anything.

Anyway, ta very much gentleman. Hope you'll be around next time I think I've broken something.

Value my car