pao312

hello everyone, i have searched high and low, in almost all the audi forums, but i cannot find an answer to my problem.

anyway, my rack died on me a few months back so i had it replaced. ever since i had it replaced ive been having a problem with air in the system. when the car is warmed up and running for about 20 minutes, i get the buzzing and clunking sound from the steering. after i park it for about 30 minutes, the steering is back to normal.

i have read every thread on the subject and have done most of the recommendations. since the rack was replaced, i assume the installers flushed the power steering.(would this be correct?) i have already replaced the clamps on the hoses coming from the reservoir and the ones on the pipes leading to the cooler. yesterday after more hours of research i read about the clamp on the hose the connects to the power steering pump. i went under the car and checked the clamp and found that it was loose. i replaced the clamp and checked the hose which seems fine. also had a mechanic check the hose and he said it was still good. after installing the clamps i proceeded to bleed the system again. i have bled a number of times already throughout this ordeal and i always get the same result. unfortunately, even after changing the clamp by the pump i still go the same result. this is what happens everytime i bleed:

wheels in the air, engine off, with the reservoir cap off, i turned the wheel lock to lock repeatedly. the bubbles start off small and foamy then bigger ones pop up. after doing it about 10 times per side, the bubbles get huge and look like the reservoir is gulping the fluid. this goes on and on and on and on. the bubbles never seem to disappear. i can also hear a swishing sound coming from near the steering column.

it's confusing because the fluid level is always constant and Iv'e never had to top off since i filled it up after the rack job. when i bleed the system its as if the air is about to be gone completely when a huge bubble comes in and its like the system has new air in it again. so i repeat the process over and over and over again.

would anyone know where else i should be checking?? there are no leaks and the fluid level is always the same and that is what is puzzling to me.

right now i'm really lost with it. i really thought the clamp by the pump was the problem. i dont see how it could be the rack or the pump when they work fine when the car is just started. shouldn't they be showing problems at all times if they were busted?

just a few hours ago after i installed the clamps, when i was bleeding, i turned the wheel lock to lock about 40 times and there was still air. should i bleed it some more??

i hope someone with experience in this could help me out. everything seems fine except the air that is somehow getting in. when i start to drive it up til about 20 minutes the power steering feels perfect. then it gradually degrades til it feels like it does when the reservoir is low. ive been dealing with this problem for the most part of the year and i cant seem to get it. any help at all would be greatly appreciated!!!!

HELP!

jschick

my only thought would be if their are no leaks and the rack is good then look for a bad pump! easy to change but can't say for sure it will solve it, but that would be my next step. it could be a defective rack, but for $50 you should be able to grab a used pump and swap out quickly vrs the rack which is a real pain!

turbo510

Just a thought but next time you try bleeding the system, try stretching a piece of saran wrap across the filler opening and seal with a rubber band. See it the plastic film is pulled down, or if the bubbles get to be less. This might eliminate the only usual place where the atmosphere and fluid meet.

pao312

@jschick - i was hoping that i wouldn't have to change the pump since the mechanics that did my rack said they tested the pump and that it was still good. and if it is the pump, could there be an explanation on why it only acts up after driving for awhile? i also dont hear a whine which i think is a symptom of the pump going bad. my problem is more on the vibration and clunking on the wheel.

@turbo510 - thanks for the suggestion, im definitely gonna try the saran wrap so i can narrow down where the air is coming in. i'm gonna try to bleed the system again this weekend, hopefully there will be less bubbles than last time although i'm definitely not getting my hopes up.

A64.2L

I found the "L" shaped plastic part, that has two filter screens, dislodged from it's prees-fit location in the bottom of my brake fluid resivour. I used a pair of forceps to reposition the part and press it back into place.
the filter screen serves two purposes:
1) it filters particles from the brake fluid returning from the system before it is recirculated back to the pump.
2) it also acts as and Air / Fluid separator. A filter screen has a property called Bubble pressure. This bubble pressure is the pressure required to pull a miniscous across the membrane. It is easier to pull fluid through the pores then it is to pull Air. As such with the filter screen in place air returning from the system will not be allowed to return to the system only fluid will return and this will prevent froth from being created from air bubbles that are left in the system even after bleeding.
So verified they have to filter screens in place in the bottom of your Reservoir.

clancy

Barry Arsenault

Have had this air problem in power steering for months and finally after exhausting all of the fix recommendations I finally found a post that solved
my problem. Turns out there is a screen/filter in the bottom of the power steering tank that through **** poor engineering can dislocate causing much turmoil in the fluid in the tank and the air is being made right in the tank. Kind of like a frothing process. Easy way to see if your screen has dislocated is to remove the cap while running and if there is a geyser like action in tank it has come off. I removed tank and after 20 minutes or so I finally got it locked back in place and replaced the tank. Problem solved. Now this screen is installed before the top half of tank is assembles so the screen is larger than the fill cap hole so get ready to spend some time fishing tools down the hole to get it back in place. It probably would have been easier to just buy a new tank but I am cheap so I took the hard route. I was just getting ready to buy a new pump so I am really glad I found the post from another person about this fix. I wonder how many racks and pumps have been replaced because of this assinine issue that Audi could fix just by plastiwelding this screen in place.

grayjay

I am pretty sure that where this solution description by A64.2L which mentions the "brake fluid reservoir" should instead be for the " PS fluid reservoir". This one detail had me slightly confused when I first read this.

I recently changed a "bad" PS pump, bled the system but was having exact same problem with a geyser of foamy fluid leaking out the vent hole of the cap, resulting in low fluid level and terrible groaning with PS assist going away after just a few miles driving. I tried replacing the low pressure suction hose from tank to pump thinking it might have a leak that was drawing in bubbles but the new hose made no difference. This description of the reservoir filter screen was key for fixing. I drained the reservoir (again) to check the filter screen. It did not even visually appear to be badly out of place but I removed with long needle nose pliers and reinstalled it firmly in the support groove. This made all the difference, when I refilled the reservoir the pentosin geyser was gone and again works for more than 5 miles! many thanks.

I would suspect that my original PS probably was not even bad, the loose bubble screen filter was the entire problem, I bet than many perfectly good PS pumps have been replaced for same reason.

One tip on draining the PS reservoir, this can easily be accomplished using a 4 foot long piece of 1/8" diameter plastic tubing to siphon the PS fluid out of the reservoir, save that poor turkey baster for use at thanksgiving.

desertsage

Grayjay, thanks for this post. I just finished installing my new PS pump (and alternator), bled the system, but noticed that my PS fluid looked murky and full of foamy bubbles. I'd never seen it like this but maybe I'd never looked immediately after or while the engine was running. The steering wheel feels so light to the touch now but I am hearing a very slight groaning noise. I guess I'd better clean that screen. Had no idea that there is one. I'd been wondering, while replacing the pump, if I should be draining the entire system and refilling with fresh fluid. Hadn't read anything about this being required or recommended.

Edit: I just sucked the fluid out of the reservoir and attempted to remove the screen, which looks clean on the top surface. When you said that you pulled the screen out with needle nose pliers, did you do that by grabbing the little tabs on each end? I pulled on those pretty stiffly but was afraid to break something so gave up, figuring I should leave well enough alone for now. If you have a chance, maybe you could let me know how you removed that screen? Thanks!

Randy

grayjay

DS-
I did get the screen out by alternately tugging on the 2 small tabs. A long screwdriver blade can also help to manipulate the screen. Note that the screen is too large to remove from the top filler hole, cannot be replaced without replacing the entire tank. Despite having old, dirty fluid in my system, there was no noticeable particulates stuck on the screen.