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Intermittent popcorn sound from front passenger side

1961 Views 16 Replies 5 Participants Last post by  passat03wagon
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I have a 2003 1.8T wagon with 115k miles and I'm hearing an intermittent popcorn type sound from the front passenger side. If I drive for a while then I'll sometimes hear it at low speeds like 20mph. It is a very low muffled sound but if I put my foot on the brake pedal I can feel it.

The obvious suspect is the CV joint because I was recently in the passenger footwell during an exhaust downpipe replacement and in the process I tore the outer CV boot. However I went to a parking lot and did many full circles with the car in both directions, sometimes accelerated, and I heard nothing. I also tried some other things like backing up going forward repeatedly. Sometimes I'd hear a single pop while backing up but it seems arbitrary. Also the sound is muffled not like you hear on youtube videos of bad joints clacking about.

On each front tire I did the 12-6 and 3-9 test where you jack up only that tire and then wiggle it back and forth in those directions. For both tires the 12-6 is solid.

The front passenger tire 3-9 is loose by 1/16" of an inch, meaning if I take a single hand and put it on the front at 3 or 9 I can move the tire 1/16" without much effort. If I use two hands for 3-9, 3 the hand on the front and 9 the hand on the back (it's more accurate this way) and I really force it I can make it move another 1/16" for a total of 1/8". But also I think by forcing it I'd guess I'm still flexing the rubber somewhat, even with the front/back hand positions to minimize the flex.

The front driver tire 3-9 seemingly isn't loose. If I use the single hand test I can move it all of 1/64" and I can't feel it. If I use the two hands test I can flex it 1/16" to slightly less than 1/8", but again I can't feel it like I can on the passenger side.

Here's a picture from when I did the tests. Basically I put the measuring tape up about halfway so I could get accurate measurements, in case that means anything, I don't know.



I checked the tie rods since they're usually associated with 3-9 looseness but I don't see any difference between them. I also tried a prybar and I don't see any difference but also I've never done this before so I'm not sure exactly what I'm supposed to see. I watched them as I did the tests and on the passenger side I saw the slightest movement but hardly anything. Here's a picture of the upper suspension on the front passenger side:



Does this sound like a suspension issue and should I be concerned about the play on the passenger side?
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Next step: Check under the battery tray, that's where the steering rack attaches to the body, with time and vibration it gets loose producing that kind of sound. Make sure both sides are tight as they should. Good luck.
I would be looking for loose bolts in the subframe, upper strut to body mounts or even the top strut nut. They can all cause isolated popping sounds that would not be felt in the steering wheel. It would also be a good idea to check the from caliper carrier bolts.
just as a notation as to loose suspension parts.....To check ball joints,tie rods,control arms etc. after jacking car up, I lower the control arms (different heights)onto some individual wooden blocks ,plywood shims (you get the picture) to where tire is just maybe a quarter of an inch off ground and both lower control arms are in about there actual driving orientation. I do this because sometimes when car is jacked up and suspension "hanging" the components (ball joints etc.) have moved/rotated to unworn areas in the individual components tightening things up ,just a thought
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Next step: Check under the battery tray, that's where the steering rack attaches to the body, with time and vibration it gets loose producing that kind of sound. Make sure both sides are tight as they should. Good luck.
I pulled the battery and tray yesterday. To the left of the drain hole and near the ground mount bolt is a steering gear mount bolt with a weird head going through a plate that appears to be welded in place. The Haynes manual does not say the head type but it appears to be a 12-point 10mm socket head screw according to ETKA. I don't have that socket. There are 3 of the steering gear bolts it says, one is on the other is on the other side of the cowl and one is accessible under the car near one of the upper two but I'm not sure which. Are those the bolts you think I should tighten? (I assume to the Haynes torque spec of 48 ft-lbs)

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Yes, those are the ones. A 12-point fits.

I like what cchief22 said about raising the suspension to near ride height to check the play or looseness in the arms/tie rods.
Everything I have metric is 6-point. I ordered this 7-19mm set of 12-points for $25 from amazon and hopefully that's all the sizes of 12-point that I'll ever encounter on this car.

just as a notation as to loose suspension parts.....To check ball joints,tie rods,control arms etc. after jacking car up, I lower the control arms (different heights)onto some individual wooden blocks ,plywood shims (you get the picture) to where tire is just maybe a quarter of an inch off ground and both lower control arms are in about there actual driving orientation. I do this because sometimes when car is jacked up and suspension "hanging" the components (ball joints etc.) have moved/rotated to unworn areas in the individual components tightening things up ,just a thought
Ok I will try that after I check all the bolts suggested.
I tightened all the steering wheel bolts to 48 ft-lbs. The upper two weren't at 48 ft-lbs and turned a bit. The one accessible from below was already at 48 ft-lbs, and a bit of a pain to get to. I had to use 3 extensions because two (totaling 16") wasn't long enough. The extension at the end is a wobble.



I also tightened all the upper-control-arm-mount-to-body bolts and then rested the suspension on wood but I still can't tell what is loose. I was able to turn the outer tie rod shaft with a vice grip and it felt smooth to turn not loose.

I bought a cheap $40 front end service kit w/ arm puller off ebay and next I'll try disconnecting the tie rod from the knuckle and I'll see if I could feel play in the rod. I've been eyeing the HD aftermarket version from Meyle as a replacement if needed.
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Also look for S4 style upgraded ones. The whole outer is solid metal, not set in a rubber bushing like the normal ones. https://www.fcpeuro.com/products/audi-steering-tie-rod-assembly-front-s4-4b0419801g
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I was unable to disconnect the tie rod from the knuckle. The pinch bolt nut is rusted on the bolt. I hit it with PB but the real problem is the bolt does not have that weird head to stop it from turning. I can't get any socket on there to counterhold. Also I tried a wrench on the head but I can't hold it in place as I try to unfasten the nut. I'm guessing it's aftermarket? Here's a pic:



And here's a pic of what I think the bolt head is actually supposed to look like, which would stop it from turning:



Any ideas? On top of that I sheared off the head of the toe-in curve bolt (the vertical bolt next to the pinch that goes into the tie rod). I hope it's ok to drive without it.
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The pinch bolt not only pinches, but slides through a cut out on the side of the tie rod ball joint insert. Kind of double duty. If you can spin the bolt, then you should be able to punch it out. The only problem I see you having is that in shearing the top bolt, you may have spun the ball joint a little against the pinch bolt, thus again pinching it from another direction.
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What do you mean by punch it out though because the nut is frozen on it. When I turn the nut the head turns and I can't counterhold on the head with enough force that i can undo the nut. I probably need a different tool to hold on the head but I don't know what.

Update: Ok I got it. I was able to loosen it by positioning myself directly under the knuckle looking up so that way both hands were pushing up. The extra shot of PB may have helped too...



Update #2: The outer tie rod ball joint has a little play. When I move its joint insert (the piece that goes into the pinch) up and down I can feel a little movement, it's not stiff. The inner feels pretty stiff and the rod stays in position when I let it hang so that part is probably ok. I'm going to replace the whole thing though.
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Sounds like you got it off, but I was meaning to cut the nut off and punch out the bolt. Go ahead and buy one of those bottles of antiseize with the brush in the lid. Being in the north, you'll want to apply it to every bolt and ball joint connection you remove and/or replace.
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amen, and although you are not doing the control arms or other suspension components while you are "under" there PB B'laster / liquid wrench nuts and appropriate fasteners for future removal
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Kroil is now my go to rust buster. That stuff works wonders.
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funny.....my Dad swore by it (restored Model As) found a gallon of it in the back of his garage ,it had "rusted" to the damp floor and all of it had drained out,seriously just as good as PB, L-wrench.
I replaced both tie rods with Meyle 1160308227HD. The old passenger tie rod outer joint had loosened more since last summer.

I replaced the passenger axle with Cardone 66-7241 since the old axle's outer boot was torn and I thought it too much trouble to rebuild.

It will take a while before I can say whether this issue is solved. This summer it was much less likely to happen than last summer and I didn't do anything in that area.
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