B5.5 Auto Tranny 3-2 Downshift Clunk
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  1. #1
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    B5.5 Auto Tranny 3-2 Downshift Clunk

    Hello all, been reading for awhile but this is my first post (usually I can find everything I need on here!).

    I am the second owner of an 03 Passat GLX V6 FWD 5sp auto wagon with 71k miles. As far as I can tell from the previous owner's maintenance records, the car regularly had all required service done by VW dealer. I've done some searching here but can't seem to find the same symptoms to my tranny "clunk."

    It consistently occurs once the engine has warmed up (i.e., after cold start immediately driving it is okay) and SPECIFICALLY downshifting from 3-2, with the shift point occurring at EXACTLY 10 mph (in Tip mode if I force the downshift before 10 mph it's smooth). Coasting or braking to stop, there is a very firm clunk you can feel thru the steering column, pedals, and even seat of the pants. With the windows down, you can hear it too. It almost sounds like something is snapping down there under the car, i.e., sounds more like a click than clunk. Other downshifts are okay (I also get the 2-1 "clunk" but it's very minor by comparison) and there all upshift are smooth. The problem has gotten worse since I first noticed it about 4 months ago.

    At 68k I had the right motor mount and both tranny mounts replaced. Also had the dealer ran a diagnostic on the tranny clunk at the time but service advisor said no trouble codes found.

    Anybody else experience a 3-2 clunk at 10 mph? Any ideas what the problem is?

    As the car has previously been serviced by dealer, the ATF and filter has never been changed, given the sealed for life philosophy. Could old ATF be my problem? Hoping for an easy fix as opposed to not... extended warranty will be up in half a year!

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  3. #2
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    First thing i would do is get under the car and check the motor mounts again, its easy to tell if they have failed because of the purple goo. If one failed awhile back it probably wasnt long till the other one failed too. Check your cv boots for tears this makes noise sometimes as well.

  4. #3
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    Thanks for that heads up! I probably won't be able to take a look under the car until the holiday weekend.

    I have to go back and check the old service record, but I am fairly sure the left motor mount was changed around 50k already and that the CV boots had been changed too near that mileage (all this by previous owner). I will go back to double check this.

  5. #4
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    don't forget the frount mount too called the Snub mount. on the bottom on the radiator support.

  6. #5
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    I apologize to anyone who has looked up this thread but found no answers posted. I have been in and out of town/out of the country for the last several months and haven't had time to take a look at my car. (I admit I also do not like to bother with the car when the weather is freezing outside.)

    All mounts are in good condition. In fact, left motor mount and both transmission mounts are relatively new as well, as in recently replaced. Also recently had the transmission wiring cleaned and TCM reflashed by the dealer but to no avail.

    I am 95% sure that the problem might be largely remedied by ATF and filter replacement, which is also the next course of action recommended by the dealer service advisor. I know it's a bit of a pain to DIY without the appropriate tools on the VW. Don't know when I will get to it but anyone who has this exact problem, I suggest replace your ATF and filter first and see!

  7. #6
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    An ATF fluid and filter change are always good things to do, but they won't fix a broken tranny.

    The best thing is to get a scan code from VAG-COM to see if it gives you a more detailed fault code. The generic OBD II scanners will not get you the tranny codes.

    The hard downshifting can be caused by bad solenoids in the valve body of the tranny. The VAG-COM scan can interogate the tranny and provide codes that point to certain problem areas.

    The hard downshifting can also be caused by a bad MAF.

  8. #7
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    There was a software update for clunking, I am not sure if it was only for the 4MO.

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    Thank you everybody for most helpful posts! I am sorry I do not check back as frequently as I think I should. I thought I posted a reply - in fact I remember writing one up - but I guess it was lost. Mileage right now is at 88k.

    To summarize where I am now:

    1. Mounts - Engine and tranny mounts were checked and are good. Snub mount has no goo showing either.

    2. CV boots - Both right and left had torn at one point or another while I experienced the clunk but they were fixed and the clunk still remains. The clunk also started happening before tears appeared in the boots.

    3. VAG-COM - Dealer has scanned TCM with VAG-COM twice for transmission trouble codes and told me they came up with none.

    4. TCM reflash - The dealer, when scanned, also reflashed my TCM with the latest software available for 03 Passat FWD V6. Unfortunately, I don't have the specs or version info on that update. I could ask if you guys think it will be helpful to. Didn't seem to do anything major except let the tranny relearn the driver adapted shift points.

    5. ATF fluid and filter change - Had this done to spec by NGP Lorton and the guys were great about it. They let me take a look under the car while it was up on the lift cooling. ATF was of course old looking and very dark so it was overdue for a change. No metal pieces or shavings. Nothing looked particularly out of the ordinary given age and mileage of the car. With fresh fluid and a new filter in there, the tranny shifts at all points much smoother but the clunk is still there. Oddly, it comes and goes. Sometimes it's fine, other times you will get a clunk - always 3-2 and at 10 mph. Yet other times you'll feel something but nothing the passengers will notice.

    @Dave - I thought about the MAF but have not gotten to that yet. I spoke with the guys at NGP and they told me it's more than likely the solenoids in the valve body are going bad. They have seen this in a number of B5/5.5 Passats and claim it to happen more often than you might think. I wish this weren't the case, but the NGP guys said the same thing as you did about the fluid change. It don't fix a bad transmission. I hope I'm not out of luck.

    Thanks again for the help, folks.

  10. #9
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    I had a similar problem when it down shifted from 4-3 it felt as if I were driving at 40mph hitting a speed bump. Got an ecu error code from vag com from the transmission and abs codes went off aswell. Turned out my intKe got loose and the car was choking and had to clean the throttle valve. 3 days later cel went off and car drove good as ever

  11. #10
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    My 2002 V6 4 motion has had this problem since 30k. i am now at 80k with many new parts it
    still does the 3-2 clunk only when its warm. If you find a solution please post i gave up years ago.

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    Im not much help, but I also experience the same "clunk" downshifting from 3-2 or 2-1, cant really tell, but I suspect it is 3-2. I have an 03 v6 wagon with 111K miles. No error codes from the dealership scanner. If I thought a fluid & filter change would not cause more tranny troubles than what I have, I'd do it. But it makes me nervous. I am trying to get an appt with a local VW indy shop to see what he can find, I'll post results when I finid out.

  13. #12
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    Why would a fluid and filter change make you nervous? I'd do those, clean the MAF, and see what happens. And what do you expect the Indy shop to find that the dealer didn't?

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    Last car I had in with a clunking downshift was fixed with a fluid/filter change.

  15. #14
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    Quote Originally Posted by Dustin92 View Post
    Im not much help, but I also experience the same "clunk" downshifting from 3-2 or 2-1, cant really tell, but I suspect it is 3-2. I have an 03 v6 wagon with 111K miles. No error codes from the dealership scanner. If I thought a fluid & filter change would not cause more tranny troubles than what I have, I'd do it. But it makes me nervous. I am trying to get an appt with a local VW indy shop to see what he can find, I'll post results when I finid out.
    I believe you can heavily wear out the transmission driving it that way. I found out my problem, it was an air leak in my intake. The MAF would get a reading amount from the air going through the filter but it was receiving a lot more and with debri from the boot that connects to the throttle body which got loose. Don't really know how to explain myself but it is how much air the maf reads that reflects the timing when the auto trans will shift. That is why no fault code appears on a vag com. I simply re attached the loose intake boot connected to the throttle body and problem was solved. Check for cracks aswell.

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