Transmission troubles - 2006 STS 3.6
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Cadillac STS Forum - 2005 through 2012 Discussion, Transmission troubles - 2006 STS 3.6 in Past Cadillac Vehicle Discussion; I'm back! With another issue, sadly... I'm not sure if the car has always done this, but i don't think ...
  1. #1
    CadiTamer is offline Cadillac Owners Member
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    Transmission troubles - 2006 STS 3.6

    I'm back! With another issue, sadly...

    I'm not sure if the car has always done this, but i don't think it has.
    There's a few funny things: One, when the car goes from 3rd to 4th and 4th to 5th, it's almost like there are two shifts. The RPM will drop a bit, and then drop again. This happens after a bit of city driving, but not when the car is cold. When the car is cold, the shifts are all nice "snaps." It'll go from 1st to 2nd in about half a second or less, and then 2nd to 3rd in the same amount of time. When the car is warmed up, the shifts are smoother, but also longer. I feel like there's more slip in each shift, and i'm not sure if that's normal.

    Another thing i've noticed. When the car is cold, it'll go into drive, and reverse perfectly fine. Sometimes if it's warm, then sits an hour or so, and is restarted, it might take a second to make the transition from reverse to drive. If i give it throttle during that time, the engine just freewheels. There's no "hard" engagement of drive when this happens.

    When climbing hills in 5th gear around 40mph, i can here kinda a "whrrrmmrrrmmmrrmm" (Nice technical term there). It SOUNDS like the engine is revving up a bit, and then being bogged down, but the tach is dead steady, and my Ultraguage is showing the RPMs to be nearly completely constant. There might be a deviation of about 10rpm at 2K, and maybe 50RPM at 4.5K. I can't feel it in the car, and the speed is steady, but i do hear something strange in there.

    If i floor it, the car will shift through all gears as expected, and there's nothing funny happening. (Except the car getting hard to keep in a straight line around 130)

    I have no clue if the fluid has ever been changed, but judging by the oil, brake fluid, and power steering fluid, i'm somewhat certain that it hasn't been changed. I'm thinking maybe a fluid/filter change and a bottle of the magical Lucas Stop Slip stuff could fix things up for a bit if the TC is on its way out. I'm not really equipped to drop the transmission and replace the TC, but i would much rather do that than drop the transmission, haul it off, get it rebuilt, and put it back in. At that point, i may as well just get a used transmission.

    I just dropped $500 on tires and an alignment, so i'm a bit short on money ATM... If someone has any ideas that might help my transmission, that'd be nice. Or if someone could say "Change the plugs" with confidence that could fix it, i'd really like to hear that

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  3. #2
    Guy.Seminerio is online now Cadillac Owners Connoisseur
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    Re: Transmission troubles

    How many miles are on it? Before I got to the part where you mention changing the fluid, I was thinking just that. Not saying it's going to solve it but it might help. The manual specifies 50-80k miles to replace the fluid. Just have it drained. Not flushed. If you're taking it to a dealer they should know not to flush anyway.

    Possibly the tranny starts acting up when the fluid warms up because the fluid is old and no longer something something something. Not sure the technical details behind it but you get the idea.

  4. #3
    CadiTamer is offline Cadillac Owners Member
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    Re: Transmission troubles

    It's at 128K right now. It's doing a lot of what my Plymouth did before i changed the fluid... Plymouth would shift nice and firm while cold, and then get mooshy once it got warmed up.

    I would replace the fluid myself... I don't trust other people with my vehicles. For me to even buy the oil, and filters, for my car, and trust another company to install it (have to have receipts of oil changes for my warranty) is a BIG deal for me. Looks like it shouldn't be too bad to drop the pan and replace the filter and fluid.

    I know warm fluid is thinner which means less friction... (You can tell i'm really wanting it to be just fluid)

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    1BadCadSTS's Avatar
    1BadCadSTS is offline Cadillac Owners Connoisseur
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    How do you plan on adding that fluid back in?

    Fill port is next to the cat requires the car running warm and on a level surface to add.

    Goodluck.

  6. #5
    Guy.Seminerio is online now Cadillac Owners Connoisseur
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    Re: Transmission troubles

    That's a hell of a lot of miles for the fluid for never to have been changed. I know you're not the first owner but assuming it was never done, damn.

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    CadiTamer is offline Cadillac Owners Member
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    Re: Transmission troubles

    Quote Originally Posted by 1BadCadSTS View Post
    How do you plan on adding that fluid back in?

    Fill port is next to the cat requires the car running warm and on a level surface to add.

    Goodluck.
    My friend has a vehicle that's similar, and has a huge syringe that sucks in one side, and pumps out the other. Was designed to be used to pump coolant into X-ray machines, and is also useful for transmission and power steering changes.

    Quote Originally Posted by Guy.Seminerio View Post
    That's a hell of a lot of miles for the fluid for never to have been changed. I know you're not the first owner but assuming it was never done, damn.
    There's this stupid idea down here that says it's bad to change transmission fluid. My Plymouth was at 145k without a change, and another friend has a 2002 S10 with 130k, and refuses to change the fluid in it because he thinks it'll ruin the transmission.

    ----------

    These transmissions get Dexron, right?

  8. #7
    CadiTamer is offline Cadillac Owners Member
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    Re: Transmission troubles - 2006 STS 3.6

    The little noise i've noticed has turned into something i can feel. Seems to happen whenever the torque converter locks up until i hit about 50MPH.

    I really hope the torque converter in this thing isn't dying... This really sucks, because my warranty takes effect in a week.

    On another note, Dexron IV is freaking expensive!


    EDIT: I was just driving to the store, and then stopped at a red light... Noticed a new sound... sort've a hum/growl. Car took off fine from the red light, but when i stopped before turning into my neighborhood, the car didn't want to move. Was at about 3K by the time it started to go... It got down the road all right, and then into the drive way... When i shifted into reverse, nothing happened. Put it in park, turned it off, and then let it sit for about 10 minutes and started it again. Went into reverse fine, and then made it about 10 feet before it made a pretty noticeable growling sound. Immediately stopped, put it in park, and turned it off. Waited a bit, and then started it, quickly got it in the driveway, and there it sits...

    I see NO evidence of fluid loss, but it's sounding like low fluid to me... Could an extremely clogged filter cause all of this? I would think that would cause issues with shifting and acceleration, though...

  9. #8
    CadiTamer is offline Cadillac Owners Member
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    Re: Transmission troubles - 2006 STS 3.6

    Little update: If left in drive for a while, the car will eventually creep forwards. Also seems to have more go-time after sitting for a few hours.

  10. #9
    CadiTamer is offline Cadillac Owners Member
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    Re: Transmission troubles - 2006 STS 3.6

    PROGRESS

    I took a crap-shoot and changed the filter and fluid. Checked fluid before changing, and while the car was warming up, the transmission made some angry growling sounds. Pulled the fill plug, and about .5qts of fluid hit the ground.

    It was black. Not motor oil black. It was overused motor oil black. The kind of sludgy black that comes out of cars that have gone 2 or 3 times their oil change interval. Except the fluid was as thin as water.

    So, popped the drain plug. Black. Put some in a clear container. Can't see through it. At all. Dropped the pan. More black. Everything had black fluid dripping from it. Poured some of the fluid out of the bottom of the pan into a container, sealed it, and stored it. Also took a sample of the sludge on the magnet and put it in a ziplock bag, and then did the same with the paper towel that was used to clean the pan. Felt no grit in the fluid, and saw no evidence of friction material. Found a good bit of metal shavings, but nothing huge. Assuming the fluid hasn't been changed since the car was built, most of the metal could just be from break in. I feel like some of it came off the pump, though.

    Why?

    Pulled the filter out, and the stuff that came out of the bottom of it was scary. It was a gooey sludge type mess. The fluid that came out of the top of the filter was the same. While the filter looked fine, nothing would flow through it with just gravity. It was STOPPED UP. I let the transmission drip for about an hour while me and my friend (who is a life saver; without him, i'd be at "Crap, no car." Thankfully i have awesome friends that are reliable ) went to dinner. Came back, cleaned everything up, and then put the new filter in, and put the pan back on. Tightened everything up, and started filling it. Used a funnel into some tubing, and then put that other end into the fill hole. Took about 3 quarts before it started dripping, at which point we started the car. It idled high for a few minutes while it was warming up, and then came down as usual. Except, no growling. No rattle sound. The loose metal sound i have heard all along? Gone. Took about 2 more quarts of fluid (one of which was the Lucas magic stuff) and then started dripping again. Ran it through all the gears, and then topped it off. Put the fill plug back on (NOT AS EASY AS IT SOUNDS. That thing SUCKS to get in and out. EASILY 3/4th of the time the change took was getting that stupidly positioned plug around the exhaust.) and then dropped it to the ground.

    Then drove it home. With no issues, other than the torque converter shuddering. Drove it soft for a bit, and then drove it hard, and it drove decent. Not great, but not bad. Shifted at the right times, though the shifts felt a little soft. Torque converter is still slipping, but considering i only changed at best half the fluid, i'm not surprised. The car does drive now, though, and it seems to shift and accelerate perfectly fine. Going to do this again in about two weeks, and then again two weeks after that. Should hopefully change out all the fluid, and HOPEFULLY have a transmission that can get me a little bit longer.

    So, moral of the story?

    Change the transmission fluid. Like the manual says. Religiously.

  11. #10
    C&C's Avatar
    C&C
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    Re: Transmission troubles - 2006 STS 3.6

    Good on you (and your friend). And I agree you need to do (in my opinion) one more drain and filter. You'll never get a complete change by just a drain and fill (and one more time should be sufficient). Your call though when you do the second drain (to see how it looks before deciding on a third). Good luck with your repair.

  12. #11
    Guy.Seminerio is online now Cadillac Owners Connoisseur
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    Re: Transmission troubles - 2006 STS 3.6

    Excellent. Glad to see it worked out.

  13. #12
    CadiTamer is offline Cadillac Owners Member
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    Re: Transmission troubles - 2006 STS 3.6

    I feel like a third will be in order, but will likely happen when i replace the torque converter.

    It seems to hit third kind of hard, but it's nothing horrible. Certainly not normal, but not bone shattering either. Torque converter clutch is definitely dying, though, so the torque converter will likely get replaced within the next few months. If the shifting doesn't smooth out after the next fluid change, i'll likely end up tossing the transmission and putting a low mileage used one in.

  14. #13
    CadiTamer is offline Cadillac Owners Member
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    Re: Transmission troubles - 2006 STS 3.6

    So which sounds more likely, assuming a fluid change doesn't fix my shuddering when the torque converter engages:

    The torque converter clutch is shot, and will likely completely fail soon.

    Or the torque converter clutch solenoid is dirty/defective, and just needs to be replaced?

    I've seeing some weird things happen. First, under light throttle acceleration, the torque converter engagement is EXTREMELY harsh. It makes the whole car shake when it happens. Then when climbing a hill, either it'll shudder under light throttle, or under heavy throttle i'll see the RPM DROP first, and then it'll start to shudder. It's as if the torque converter is locking up more, and then slipping. If this happens long enough, there will be a somewhat harsh disengagement of the TCC, and then the car drives perfectly until the next time the TCC engages.

    Gunk in the solenoid screen is entirely possible... I'm going to pull that out with the next fluid change. Other than the weirdness around the TCC, the car drives perfectly. No funny sounds, and at WOT, the thing will burn rubber and then shift all the way up to 5th with no issues at all. Nice smooth, quick, shifts.

    Also, sometimes it'll lock up the TCC, and nothing weird will happen. RPM will drop, it'll climb the hill, and everything is normal.

  15. #14
    dannyquest is offline Cadillac Owners Fanatic
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    Re: Transmission troubles - 2006 STS 3.6

    Sound like your torque converter needs to be replaced. Been there done that. Danny

  16. #15
    CadiTamer is offline Cadillac Owners Member
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    Re: Transmission troubles - 2006 STS 3.6

    Boo. Really not wanting to pull the transmission out of this car.

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