fatcatjohnny

Unfortunately i'm back with more issues. My car is a 2004 4.2l with 146k miles. I was driving home on the coldest night of the year so far, probably 28 to 35 degrees out and I noticed my power steering was getting louder and louder and louder, almost sounded like it was grinding at times. After 20 miles it was unbearable. It has always been a little weak though so I figured that the pump must of let go. So I changed it out with a re-manufactured unit from rockauto and flushed the system with 11s. I test drove the car a little ways down the road and all was well except the reservoir was over filled a bit and some leaked out the cap. Seemed all good after that. However after driving it to work again the noise is still there with little to no change. I seems like air is getting into the system somehow because when I open the cap the fluid is all aerated and full of bubbles. Ive re-bled it multiple times following the correct procedure and while it sounds and works great right after it's bled, after a little time idling the noise comes back and gets worse and worse. I was wondering if there are any known trouble areas where air can suddenly be introduced into the system like this. Ive been looking through the other threads for a4's and a6's online but I was looking for a fresh opinion specifically for the a8. Any help is appreciated.

fatcatjohnny

note: the noise is a high pitched whining noise which can be felt in the steering wheel and gas pedal at low speeds and becomes much worse when turning.

MP4.2+6.0

It does sound pump related from my C5 4.2 experience. Also my experience from that and various other domestic and Japanese built rides that it can take a while for system to bleed and stop aerating the fluid. The method I try sometimes is with wheels up in the air in front and motor OFF, I then crank steering wheel manually from side to side a few times to try to force air out of rack area but w/out pump running. If a remaining issue, I would guess the return (suction) hose side. Low incidence of hose issues on D3, but it comes up once in a while and more so on pressure side. Have you inspected carefully for leaks? Any sense of fluid loss pre-pump change?

Separately, I wonder if maybe you got a bad pump? From my C5 and earlier Audi experience, more noise when cold tended to be a sign the pump was tired and running at lower pressure and/or excessive clearances. Alternately and related to noise, think about whether the noise might actually be a bad pulley, whether serp belt or timing belt. It is very hard to isolate a pulley type noise to a specific location just casually listening under hood with motor running. If you either use a stethoscope and touch the metal parts or do the poor man's version (super long big screwdriver with blade touching part and plastic end held to ear), you can often isolate where the noise is louder. Just touch it to some non moving metal area still on the part being checked--steering pump, idler pullies, water pump, tensioner assemblies, etc. The comparatively loud ones, gravelly ones or any that seem to match resonance and tone of what you hear casually are the suspects.

Shark_V8

My 2004 had a rack replacement at 100K miles. it was like $2K cdn, which I thought was pretty reasonable.

Reservoir, pump and rack. Could be cavitating the pump. That would be nasty,

I had a Porsche PS reservoir out once and was surprised how dirty the foam screen was at the bottom of it.

fatcatjohnny

I appreciate the quick reply again sir. I am certain that this is a power steering related issue only because that it does "go away" when that system is bled again. The bubbles in the reservoir are a pretty good sign to me. I was wondering if it was cavitation from the pump causing it too. I have the system apart right now because I was checking for bad hoses/ loose clamps. I will put it back together and listen to that pump with the stethoscope and report back here.

dvs_dave

You have a failing/perished suction hose (reservoir to pump) which is allowing air into the system. Seen exact same symptoms on another of my steeds in the past.

richard-tx

+1 When the suction side leaks, it sucks air in, Check for spongy hoses and replace.

fatcatjohnny

I got the car all back together and took it for a 30 mile or so drive and it worked great! However the next morning the pump starts screaming like crazy. Sure enough the suction hose looks to be a little wet down by the pump. From what I've seen that hose is 80 to 100 bucks?!?! Sounds like highway robbery to me. Maybe I have a piece of hose laying around that I can squeeze in it's place.

Mister Bally

Thats the price of admission with these cars.
The car was about $75-$85k when new. Service parts are pricd accordingly.
Price a OEM altenator or steering rack for other examples.

richard-tx

Take the hose off and to a place that makes hydraulic hoses. They should be able to reuse the ends and build you a replacement. Cost? About $30 - $80 Everyone charges about $100 an hour for labor. If it were mine I would consider the hose cheap and pay it. Put another way, that hose costs about 2-3 tanks of gasoline.