Failing torque converter.

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Thread: Failing torque converter.

  1. #1
    PZ
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    Failing torque converter.

    1st, the history. I use Tiptronic almost exclusively (better mileage with lower rpm shifts).

    70K bought used, fluid/filter change with Mobil. No change, shifted like stock.

    100K , fluid/filter change with Redline D4. Smoother shifting, much smoother downshifts into 1st. 2 long road trips this summer (9000 miles) including lots of mountian driving, no problems.

    115K (2 weeks ago), noticed the rpm float/climb while upshifting under part throttle. Slightly worse when warm, it would rise up to 400rpm. TC stayed locked while in gear.

    Last Sunday, out for a Sunday Morning Drive (think canyon run). At 90-100mph, TC starts to unlock in 5th and revs climb 400 rpm. Shut down for lunch, normal speeds on the drive home and it seemed fine.

    Yesterday, take it Sipes, 40 miles up, 20+ hard miles while being scanned. All seems normal, no trans codes just the usual Cat code and a new secondary air flow problem. TC shows locking when it should. Trans temp rises to 90c and stays (as it should).

    Drive 40miles home in near stop and go highway rush hour traffic. Get within 10 miles of home and traffic opens up. Get up to 60 and notice revs are climbing too high. 2500 at 60 and it jumps to 2800 if I push the gas. The rest of the drive home, the TC will not lock in any gear.

    Drive to work this AM and car is fine

    It seems similar to this W8 thread about a failed TC.
    https://www.passatworld.com/forums/sh...d.php?t=237369

    I guess we are taking the Golf on this weekend's trip to Austin.

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  3. #2
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    While I'll be the first to admit that I know NOTHING about the fluid flow through these trans/converters, I DO know what happens when a failing converter is allowed to run in a Dodge 46RE trans. $2000 worth of rebuild due to metallic fragments scattered throughout the clutches, bands and valve body...

  4. #3
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    Dude, that sucks. I had to have mine replaced on my 03 W8 6 months ago. Called the dealer, thye wanted $4000 to replace, then found a GREAT Indy, $2000 which was still hard to swollow!

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  6. #4
    PZ
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    I don't know if the TC is failing or just failing to lock. From what I have seen, all 4MO cars tend to eat converters. The S4 and W8 were the worst. A local Audi mechanic says a seal gets displaced in the TC.

    So far, the TC is just failing to lock after 100 miles of hard driving. The scan showed normal locking while driven yesterday and it was not until driving for an hour in rush hour traffic that it got worse.

    Since I work less than 6 miles from home, it may take a while for it to show up again. I guess I have to see if Sipes is brave (or stupid) enough to go on the next SMD with me. I am sure it will show up again.

    If it holds up locally, I may not bother to repair it. I get a new car in 2 years either way (that's when both cars are paid off). I would rather not drop a 4MO trans in my garage, but I will not pay to have it done. I would even be willing to do a manual swap if I can a donor car.

  7. #5
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    I've never had to go into one of these transmissions but there has to be a lockup solenoid that controls the torque converter lockup I would imagine. It really sounds like the solenoid is getting hot and then failing. Usually a mechanical failure in the torque converter will not come and go so erratically like yours is doing, especially where lockup is concerned.

  8. #6
    PZ
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    Yeah, I was thinking it would be an all or nothing on the lockup. My only worry is that the solenoid is getting a bad signal from the TCU. I did not have a code for a bad TC solenoid, so I will wait and see if it gets worse.

  9. #7
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    with the vag-com when i was watching the variables as we were around we had only one sudden opening of the TC at an odd time. trans temp was at a 90 degree Celsius.

    also, i noted one of the solenoids listed in one of the measuring blocks as "solenoid 7" (it's in block 3, 4 or 5... same one as tcc status) the numbers we were getting were along the lines of "0.000 A" was open "0.300 - 0.638" was listed oddly as "regular" not sure what it means. and the TCC closes was at a variable of "0.700 A" and above slightly more, but still within the .7 range. now, i don't know if these are amperage measurements, but these are the most conclusive pieces of data i was able to extrapolate from the car in the drive.

    pz, if you're ok with it, want me to post up a link to the data logged?
    i figure L1tech, or others may be able to give a little better insight.

  10. #8
    PZ
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    Yeah, you can post it up but I don't know if it will help unitl we catch it in the act full time. Then we can see if the sensor is sending the wrong signal or if the TC is ignoring it.

  11. #9
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    If I make it over to the shop today I will see if I can dig up a little more info on whether this uses a tcc solenoid or not, I have heard that it may be purely mechanical. The readings you are seeing are amps of the different solenoids and they should change as the car goes into different gears. If you have the the data log I would love to have a look at it, the more info the better.

  12. #10
    PZ
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    Yes, there is a soleniod and it shows a set reading with the TC open, active and locked. It appeared to be correct, but the car did not act up until the drive home. If you PM me your email, I can send the log.

    It seems to be fine on my short commute except for the little blip in rpm on upshifts.

  13. #11
    PZ
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    Went on a 375 mile round trip Sunday at normal highway speeds (75 indicated) and with less than a 30 minute stop halfway, the car was fine. I can only guess it is overheating and I will install an extra trans cooler and see how it hold up.

  14. #12
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    Some slippage in the TC is normal. There is a Reg mode that allows for up to 510rpm of slip in gear. To my knowledge it was put in for fuel economy and comfort purposes in that it keeps the tranny from downshifting if there is a small throttle application.

  15. #13
    PZ
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    Quote Originally Posted by Mister T View Post
    Some slippage in the TC is normal. There is a Reg mode that allows for up to 510rpm of slip in gear. To my knowledge it was put in for fuel economy and comfort purposes in that it keeps the tranny from downshifting if there is a small throttle application.
    In Tiptronic, the TC locks in 3rd, 4th and 5th. It should not unlock unless the throttle is floored. The upshifts were quite firm, with just a quick drop in rpm.

    When this problem started, the rpm would jump just a little when I upshifted. The warmer the car, the higher the jump (up to 200 rpm). Now that it is cooler (45 at night), the car is acting just like it used to before this started. Nice firm shifts with no rpm blip.

    When the TC unlocked on the high speed drive, it was in tiptronic and only at part throttle. Temps were in the mid 70s.

    When the TC unlocked after the rush hour heavy traffic, it was in all gears at any throttle input. It did not lock at all for the last few miles. Testing prior to the traffic showed the trans at temp, but not overheating.

    The 375 mile trip was in 70 degree weather and the TC was fine.

    I think the trans is overheating when used heavily. I don't know how why it did not show up on testing, maybe it was not long enough to overwhelm the stock trans cooler.

    With as many W8, S4 and 4MO trans that have failed, I would rather add an external trans cooler to the car now.

  16. #14
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    Maybe next time you do a fluid change in your tranny use an ATF that does well in high heat. A tranny cooler is never a bad idea.

  17. #15
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    Tranny cooler is a good idea as is the fluid change. As per the 200rpm blip, keep an eye on it. The viscosity of the fluid will obviously change a little as it heats up. While this is just a guess on my part, if the fluid is loosing viscosity or 'thinning' it may not create as much drag between the halves of the TC or may decrease the line pressure. Either way, if it starts frequently slipping between shifts look for a new TC (that's what I'm doing) check out IPT
    www.importperformancetrans.com a custom TC only costs $695. I know the install costs suck but at least you'll have some peace of mind and some extra WHP as a result of them making a more efficient TC.

    edit: from talking to various sources it appears that the internals of these trannies are quite rugged, it's the crummy VW spec TC's that fail

  18. #16
    PZ
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    Update: I finally got the trans to throw a code.

    1 Fault Found:
    17125 - Torque Converter Clutch: Stuck OFF / No Power being transferred P0741 - 35-10 - - - Intermittent

    The TC is now unlocking after 10 minutes or less depending on driving style. Even while locked, it will unlock at half throttle or more. It still is a smooth transition, just a 200 rpm climb at 60 and more with throttle. I guess I will change the fluid and filter when I have a chance and see if that helps.

    If the TC is fried, I will change it myself, so no labor cost involved. I just don't feel like pulling it all apart as I have enough to do right now (5 timing belts and a set of coilovers in 3 weeks time, plus 54 hours a week at work).

  19. #17
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    like i said pz, i can change my work schedule to help you out with whichever route you take...

    either way, it's another lesson for me in how our cars are configured

  20. #18
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    PM sent

  21. #19
    PZ
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    Thanks for the PM.

    Thomas, when I have some time free, we need to take another drive and watch the solenoid values as the TC tries to lock. Then I can see if the soleniod is good before I pull the pan for the fluid change.

    And now all 5 timing belts are within 2 weeks of each other. 1 down, 4 to go in the next 9 days.

  22. #20
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    Nice!

    i really wish the 01v really had some pressure sensors built into it... having those would be nice for diagnosis, or even the hydraulic ports similar to what gm does for line testing.

  23. #21
    PZ
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    Update:

    I finally changed my fluid after 4 months of my torque converter unlock problem.

    The torque converter got worse over time, but would always lock when cold. It would unlock after 10-15 minutes of driving or for multiple stops with 15 minutes or more of driving. It finally threw a code for the TC not locking.

    I drained my trans cooler and valve body using compressed air to get more fluid out. I added 6.5qts of Pentosin. The torque converter now stays locked all of the time, but I have not driven more than 45 minutes at a time (at warm temps too). The engagement is also much stronger as it locks and the rpm drop quickly. There is some minor flaring under hard throttle, but no more than 200 rpm. It had been 400-500 rpm at it's worst.

    A longer drive will tell if this has cured my torque converter problems, but right now I am pretty happy about it.

  24. #22
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    Quote Originally Posted by PZ View Post
    Update:

    I finally changed my fluid after 4 months of my torque converter unlock problem.

    The torque converter got worse over time, but would always lock when cold. It would unlock after 10-15 minutes of driving or for multiple stops with 15 minutes or more of driving. It finally threw a code for the TC not locking.

    I drained my trans cooler and valve body using compressed air to get more fluid out. I added 6.5qts of Pentosin. The torque converter now stays locked all of the time, but I have not driven more than 45 minutes at a time (at warm temps too). The engagement is also much stronger as it locks and the rpm drop quickly. There is some minor flaring under hard throttle, but no more than 200 rpm. It had been 400-500 rpm at it's worst.

    A longer drive will tell if this has cured my torque converter problems, but right now I am pretty happy about it.
    What ATF did you have in it at the time and what new ATF did you put in?

  25. #23
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    looks likec redline d4 for 15000 miles then problems, now hes put in original fluid all seems good.........um....
    good luck, as i man i just love happy endings

  26. #24
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    What did the old fluid look and smell like? If it wasn't burnt then I would wager the fluid was the issue. If it looked/smelled like it was burnt then I would keep my eye on the TC. As the saying goes in tranny shops "new fluid will not fix a bad transmission"

  27. #25
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    Quote Originally Posted by Mister T View Post
    What did the old fluid look and smell like? If it wasn't burnt then I would wager the fluid was the issue. If it looked/smelled like it was burnt then I would keep my eye on the TC. As the saying goes in tranny shops "new fluid will not fix a bad transmission"
    in both cases of me and xyro's passats neither of us had a very pungent smell to it, as if it were burnt, or any real noticeable traces thereof, so i would wager that his was not as well.

    then again, he had a far more severe case than i had, but i'm very interested to know as well...

  28. #26
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    1st change was at 70K with Mobil1. It seemed just like stock, not change in shifting at all. 2nd change was at 100K with Redline D4. Not a big change in upshifting, but downshifting was much smoother. I think the Redline just does not hold pressure as well in my trans, so the engagement was softer.

    Fluid was not burnt and came out fairly clean. Magnets had a small amount of gunk, not nearly as bad as the previous change at 100K.

    I really need to get out and hammer on the car for a few hours, but that is unlikely for the next couple of weeks.

  29. #27
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    Quote Originally Posted by PZ View Post
    1st change was at 70K with Mobil1. It seemed just like stock, not change in shifting at all. 2nd change was at 100K with Redline D4. Not a big change in upshifting, but downshifting was much smoother. I think the Redline just does not hold pressure as well in my trans, so the engagement was softer.

    Fluid was not burnt and came out fairly clean. Magnets had a small amount of gunk, not nearly as bad as the previous change at 100K.

    I really need to get out and hammer on the car for a few hours, but that is unlikely for the next couple of weeks.
    I don't know if you followed my posts a while back...but when I put Mobil one ATF in...it worked great for about 10K then started to act funny. Switch out to Maxlife and it got better. Did a fill again 2K later and it completed fixed the issue. I don't like that mobil one being in my tranny at all.

  30. #28
    PZ
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    I had the Mobil1 in for 30K and had no problems. I was trying to be proactive in the 4MO trans issues and changed it to Redline. 15K and it started acting up. No way mine was related to the Mobil1.

  31. #29
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    Its a little early but i think i might be having issues with my Mobil1 ATF. Car has been driving great for the last 6 months since rebuild. No leaks or anything.

    But yesterday it started slipping on a cold startup. As soon as i let it warm up its fine.
    same thing happened today.

    I guess the viscosity is changing with changing temps and affecting the tranny's operation. i'll keep you guys updated

  32. #30
    PZ
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    Update. Did a lot of driving in traffic last week and after an hour of stop and go, the TC unlocked and stayed unlocked once I got on the highway.

    It looks like I will be dropping the trans in June as I need it fixed before my next drive to Boston in July.
    rreyes likes this.

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