allroaddave

Ours in our 45K mile 2004 Allroad 2.7T has started whining loudly on startup, however our local dealer says that it is NOT covered under the emissions warranty. That seems very strange to me, given what it does......

Has anyone else had a different experience?

Has anyone tried to repair one? Seems to me it's just a noisey bearing, and if I can get it apart I should be able to replace the offending parts, especially since the pump is is a $500 + replacment piece.....

Edit: found an excellent how-to on rebuilding the pump, just as I thought it's a common sized bearing, I should be able to fix it.

Anyone know about the emissions warranty part of the question?

fjasper

that they won't warranty it until the computer tells you it's producing insufficient flow. As long as it's making the airflow it's supposed to, they'd probably call the noise a cosmetic problem rather than a functional problem.

More to the point, would you mind posting a link or a DIY on fixing the pump? Mine's doing it too (and it's about 80,000 miles past the warranty), and I'm not a big fan of replacing a $400 part just because a $10 bearing is bad. Let us know how it goes!

Or you can just wait until it quits pumping air, then they should replace it, but some of us have been having this noise for over a year.

allroaddave

If you do a search for secondary air pump you'll find the link, it's on the A6 forum but it was for the same setup (2.7T, auto trans) as my allroad. Here's the link....
https://www.audiworld.com/forums/sho...injection+pump

I'll do a writeup when I do mine, he wasn't very clear on how he got the bearing out but once I saw the pic of the motor - I've had these apart before so I'll do a more detailed report on that part.

He also bought his bearing at Westlake hardware, even tho this motor doesn't run all that long or under intense conditions, I'm going to buy mine from a bearing house instead of a hardware store. And one more caveat, this is just my experience, but I don't have good luck with Chinese made bearings, even those sold under "Name brand" companies. I prefer those made in the US, Germany and so on - for longevity's sakes.

fjasper

Thanks!

fjasper

I took mine apart, popped the bearings out and measured them to be 8mm ID and 22mm OD. Mine say "England" and "608S" on them, and one is a little crunchy.

Apparently 608 is a common bearing size. It looks like Milwaukee tools sells one for their routers. Those should hold up to air injector pump use, I would think. Also used in inline skates and skateboards. So if I'm feeling like treating my car to something special, maybe I'll throw in a couple of high-tech ceramic bearings at $50+ each.

allroaddave

Thanks for the size, now I can go buy one ahead of time. No harder than it is to fix, I'll probably just buy a new sealed bearing from my local bearing house and call it good - no fancy schmancy ceramics for me! ;-)

Interesting that you said the ID was 8mm (5/16") ,as in the write up I linked above the guy said it was a 1/4" ID bearing he bought - but going by the number 608, it is an 8mm ID.

fjasper

I swapped in some regular ol' bearings (Made in Bulgaria, according to the box), put it all back together and fired it up. And....it still makes the noise.

I don't really care enough to mess with it any more right now, but if you still have yours apart, you might look for other things that could be making the noise. The brushes in mine were off-center, but they were symmetric, so I figured they were supposed to be that way. Maybe one of the little aluminum compressor wheels is rubbing on something or the diffuser vanes are loose? I don't know.

I guess I should have paid more attention while I had it apart, but I was focused on the bearings.

Good luck with yours.

allroaddave

I'm going to do mine this weekend, I'll let you know what I find....there's usually a wave washer that goes behind the bearing in the bottom (the end away from the impeller), did you put that back?

If one of your bearings was "crunchy" as you put it, it seems new ones should have fixed it......

I'll put up some pics and such once I'm done....

fjasper

Mine actually had a little coil spring that was machined flat on the ends - it looked to be a pretty well-engineered little motor. I blasted it out with electronics cleaner (the liquid kind, not canned air) and wiped it down. I lubed that spring with a drop of gear oil when I put it together. It was better after I worked on it, but not quiet.

I wonder if I should have left that spring dry. There should be no relative motion between the motor shaft and the inside part of the bearing, so it shouldn't need any lube.

Maybe the shaft is turning relative to the inside race of the bearing. That would probably make some noise.

Mine started making noise after the engine compartment got unusually hot (doing a coolant flush - hours at 2000rpm while sitting still), I don't know if that's a useful clue. There is a foam piece in the bottom of the pump assembly that appears to be a noise suppressing device. Maybe that just deteriorated or came loose.

Centrifugal compressors can make a lot of noise just from chopping up the airflow as it goes through them (I think my ears are still ringing from the time years ago when I got too close to a pair of Garrett turbine engines running at low idle.) Maybe it's a noise-suppression issue rather than a noise-creation issue.

I do kind of wish I had paid more attention while I had it apart. I'll probably end up taking it apart again and having a look. Maybe I'll take the motor over to a friend of mine who rebuilds starters and generators. He might notice something I didn't.

allroaddave

Well, I've started working on mine, but for the life of me I can't see where the third bolt is that's holding the bracket in....time to do some more research.

You all made it sound like getting it out was so easy!

Edit: This thing is a bitchkitty to get out, once you do it's no big deal to take the motor apart and put some new bearings in it, but there are a few "tricks" to it. I'll have some pics to post later, but in the thread linked above, there is no way the other poster "cut a hole and knocked the bearing out" as he said he did - if he did he completely ruined the motor housing.

The right way to do it is to take the motor apart. On the impeller end, there are four tabs that stick thru the end plate, if you look closely you can see where they peened the ends out to lock the end plate on. Take a drift and a small hammer and tap the ends back straight, then lay the motor on its side and use the same drift to knock the end plate up over the tabs, it will come right off. Once you have the plate off you can tap out the old bearing and install the new one. Remember to only tap on the outside edge of the bearing as you drive it back in.

To get to the lower bearing, you have to remove the brush assembly and armature. There are four tabs on the side of the motor, carefully bend them out flush or just a bit more, then carefully tap the brush assembly out, it's all one peice. Then simply pull the armature out. The brushes and commutator on my motor were in surprisingly good condition, but the motor had a ton of black carbon dust in it from the operation of the motor - I simply blew it all out well and reassembled it, after replacing the lower bearing. The trick to that one is keeping it off the permanent magnets inside, that want to grab the bearing and your drift as you try to tap it in!

Reassembly is the reverse, once it's all back together, remember to bend the four tabs on the side back in to hold the brush assmebly in place, then take a sharp cold chisel and peen out the ends of the tabs to lock the end plate once it's back on. I used a deep socket over the shaft and put the motor in a vise to hold the end plate down tight while I peened over the ends of the tabs. Then simply put it back together, you might test it first on a battery to make sure it runs and is quiet. Mine was quiet as could be......

There is one nut down on the side of the mounting bracket that's extremely difficult to get to, good luck with that.....I wound up taking the coolant reservoir loose but even so it took an odd combination of socket, extensions and a universal joint in between to get this nut loose and tightened up again, it's the hardest part of the job, IMHO.....