awdinut

Would like to quiet down the steering pump on my 2004 4.2 and thought new fluid would be the place to start. How to do that is the question.

MP4.2+6.0

I have done this w/ my C5 4.2 so I know it there conceptually. The W12/S8 reservoir is almost inaccessible, but if yours is high up you will likely have a lot more luck with a method like this. It assumes you can easily get to the fluid reservoir and its hoses.

Basically, I take the return (suction) hose off the bottom of the reservoir and just dump out fluid and clean it out. I then stick that suction hose into a can of clean fluid. Meanwhile, I open a line AFTER the rack--which on that car is where it goes out to a small tube it uses as a hokey cooler of sorts that sits in front of the radiator. There is a rubber hose clamped to it, and I just cut the Audi factory clamp and replaced it with a small screw type clamp. I do it down there so my drain point can reach in a practical way to my oil drain pan and not spray a mess all over. (On my W12, I see that is now more like a cooling panel, so on my next belly pan drop I am going to look at it further). Anyway, now with a return line open where it can pump the junk fluid out and the suction line stuck in the new fluid can, I get the "assistant" (aka wife or kid) to operate the key. Takes like 15 seconds running to mostly suck the can (but NOT completely) and then cut the ignition immediately--NEVER LET THE PUMP RUN DRY. Then I may do part of another can depending on whether I'm seeing clean fluid exiting my drain point yet. When done, reinstall reservoir, close up clamped hoses, fill up reservoir to upper mark (for starters) w/ clean fluid, restart and let run a few minutes. It will still have some air, and fluid will froth some; might get a bit of pump noise too given invariably some air will still be in there. Once it settles down, recheck and top off. Also along way, crank wheel all the way left and all the way right to purge air more. Instructions also talk about this as an early step w/ key off as I recall, but that really takes wheels off ground to do even remotely easily.

Sci-fi_Wasabi

I would like to change my power steering fluid on my 4.2L A8 2009. MP4.2's explanation is helpful but i wanted to know if anyone had an easy way to do it on 4.2L D3.
Getting the supply or return hoses off of the reservoir looks difficult, as even with the reservoir loosened it does not move around much because of the short length of the hoses, and space is tight.
I wanted to avoid messing with connections at the cooler for fear of creating a leak on this 7 year old car. I can't see to the bottom of the reservoir but if the inside orifice to one of the supply or return ports could be cannulated with another tube that would be good.
just looking for some advice to make the work easier.

MP4.2+6.0

The one other idea is to suction it out several times. That's what I was doing on the W12 since the reservoir and lines are almost inaccessible. On that motor reservoir is just in front of but below U.S. drivers side air box. As in, a foot down from upper part of hood/motor area. From what I was pulling out compared to total system capacity, you can make progress this way. Maybe 3 or 4 cycles running it briefly in between. An oil suction type pump would have been handy. I was doing it with the old turkey baster. Plus, on a W12 with the air box out you have no MAF connected there so I was doing it over time opportunistically when air box came out for some reason. 4.2 set up should be easier just to cycle motor over several suction and fill cycles.

Sci-fi_Wasabi

thanks mp4.2, i'll give that way a try if i don't see another way.

Sci-fi_Wasabi

So, I bought 2 liters of CHF 202. I opted to just do the suck out and refill, as my present fluid looked pretty clear, it was just not green any more, more like a clear tea color, and I have had no steering issues.. The filter inside looked pretty clean too, just doing it for preventative maintenance at 100k miles.
Sucked out the the old fluid from the reservoir, put in new stuff. Started the car and turned the steering wheel lock to lock 6 times. Sucked out that fluid, put in more new fluid. I was able to do this 3 times with the first liter.
For the second liter I did it twice making sure i had a good amount left over for the final fill.
In the end my fluid was not as bright green as the fresh fluid straight from the bottle, but a bit more olive, which I'm pretty happy with, since the old fluid was probably acceptable.
I'm glad I did it this way. No spilled fluid, no issues with cracked plastic hose spouts, no removal of other parts. Worked well. Thanks for the suggestion.

richard-tx

So is your pump still making noise?

Panelhead

My hydraulic fluid smelled burnt. Used a Mitey Vac to vacuum the reservoir dry. Topped off and drove. Did again that afternoon.
The smell was better. The color was still a little dark. Did a third time.
Six months later the burnt smell was stronger so did again.
I started to do this on all our vehicles. They all now have clean fluid. One reservoir of fresh fluid at oil change (annual).
The oil change joints supposedly use Mishar's method. Who knows what fluid .they use. None like cars with belly pans. Or air boxes that have to be pulled to change an oil filter.
Get a Mitey Vac. It helps keep oil off the ground when changing motor oil. It you still pull the drain plug the amount coming out is minimal.

MP4.2+6.0

Yep... But the amount of casual proactive inspection you then do for coolant, oil and other fluid leaks, CV joint boots and a variety of other things is non-existent. Then pan comes off in worse circumstances, or the tow truck gives it a go. Pay me now, or pay me several x later...maybe on the side of the road.

On a W12, or a D4 4.0T, the filter is completely underneath anyway. In your face, but pan definitely has to come off. That and VCDS are still the best two diagnostics in my book anyway.

Panelhead

I have started vacuuming the oil and then pulling the plug. Found it can be difficult to tell if a quart was left in the pan.
Usually the vacuum gets more than the plug. But sometimes there is a quart or some left.
I like looking for leaks and rubber condition. Found one of the Audi clamps was leaking on the power steering. It was a PITA to replace the clamp and tighten a US hose clamp. It did stop a small drip.
I spray all the visible suspension rubber with 303 Protectorant. Hope it helps.