Transmission problem?

Discussion in 'Engine & Drivetrain' started by sonic_the_hedgeh, Apr 21, 2018.

  1. sonic_the_hedgeh

    sonic_the_hedgeh Member

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    My 04 yukon has 6.0 engine. It is an XL Denali with 316,000 km. When it shifts it revs slightly then goes into gear smoothly.

    I am getting the fuel filter replaced next week and the transmission fluid and filter done no flush.

    Any idea where the problem may be to cause this?

    Also noticed my steering at low speeds is better if I turn off the traction control. Which may turn off the awd.

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  2. Chubbs

    Chubbs Full Access Member

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    AWD cannot be turned on & off. The 4 wheels are being driven at all times.
    The traction control is associated entirely with the vehicle braking (& in some cases suspension) system, and not the driveline. When TC is turned off, the system shuts down a percentage of the braking effort used to control wheel spin.

    Can it be that the transmission just shifts 'sluggish' so to speak? My truck has always shifted like a slush box... It is programmed by GM to shift smoothly as possible. As time & wear takes its toll, the slug shift becomes more pronounced. Some folks install bigger servos and boost valves to firm shifts & increase hydraulic pressure within the original unit but you have to consume those options with theory of mechanics and a components useful service life.

    If you give it 3/4 accelerator like you are wanting to really move, the shifts will be, or should be, noticeably crisper.

    My driving style is slow and steady and the trans in my truck feels like it really drags the shift out. Most people are quick to have the transmission parameters changed whenever they are having a tuner modify the ECM for engine performance. This would be my preference, considering that none of the parts are being changed or upgraded; it is the same components acting within a different program that results with improvement. Most economical option, as well. At least until the orig trans' completely fails. I'm unaware of any testing or data but I would claim that modification of the engine ignition & auto transmission @ the earliest possible time in the host vehicle would extend the service life beyond the factory/engineering conservative specs, given moderate driving habits and timely oil/filter replacement, maintenance as-needed.

    Unless there was a drastic & sudden change with the trans manners, I wouldn't think it much to distress over. Over time, the shifting characteristics are bound to become looser as parts wear out and line pressure decreases. There isn't anything you can do except mask the wear by upgrading with performance parts but the underlying issue of wear & tear doesn't change. But you could certainly hasten trans failure when attempting to override a small issue instead of rebuilding or replacing the failing components, which is the only good option you have for transmission service. A fluid drain & replace can't hurt; request that only a Dexron-6 be used. The spec Dex-3 for the 800gmt is outdated technology. It was superseded by the -6 formula back in 06/07.

    http://twincharlotte.com/blog/30-common-4l60e-transmission-problems-repair-charlotte-nc/

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    Last edited: Apr 21, 2018
  3. Chubbs

    Chubbs Full Access Member

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    Have you already chosen a business that will perform the trans service? I wanted to add that if you have the maintenance performed @ GM dealer/service dept, you can ask to have a diagnostic run on the OBD to determine if any fault codes exist for the engine or transmission.

    Is the 'check engine' currently illuminated? That would be for a confirmed fault but if any detections have been made without enough variance to escalate from 'pending' status, there will not be a warning lamp. As I said before, if any sudden changes were noticed i would be looking into it but if you can't remember even how long the trans has been sluggish, not worth the paranoia. Just drive it 'til it breaks.
     
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  4. sonic_the_hedgeh

    sonic_the_hedgeh Member

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    No check engine lights. So I am changing all fluids in the drive train. I had advice from quite a few friends with mechanical knowledge and one said could be the differential. So I am changing the transmission fluid, transfer case fluid is actually dextron 3 as well, and changing the front and rear differential fluid to see if that helps. If it doesn't eliminate the problem I am sure it will prevent a costly repair bill.

    Checked service records and none indicate the diff and transfer case fluids were ever changed. (Except maybe at the dealership when it was a few years old). Anyways I hope it helps.

    Plus replacing the fuel filter since it did have error codes in the past stating 2 banks in the engine were lean.

    I will post after with results.

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  5. Chubbs

    Chubbs Full Access Member

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    Fluids & filters all the way around is 'A+' my friend.
    I don't know if the AWD TC uses the same drain/fill bolts as the 4x4 but you should apply some sealant or plumbers tape to the threads. I had to torque the bolts super tight because The drain was still seeping at spec torque.

    i know the 5.3 vin 'z' has a serviceable fuel filter but most of the non-flex engines do not. Have you checked physically or at any literature that confirms this? The 'z' models calls for a very specific disconnect tool for removal of the original fuel filter; the aftermarket units are designed with easier removal in mind.

    Take a look at the fuel filter and size up your disconnect tool then get back to me if you want some tips

    You know Dex3 is outdated right, or your only intent was using "Dex3" as ref to the TC using same spec oil as trans probably. Either way, Dex6 supersedes the 3 since 2007. i can suggest AC Delco dexron IV syn. Much better formula backwards compatible with everything orig rated DexIII.

    If the engine is running lean and randomly spitting out fault codes related to such, you very possibly are due for intake manifold gasket replacement. That or a vac leak but the intake gasket is becoming somewhat the norm from what I've been reading. If you don't see anything obviously sketchy like a cracked tube or fitting and the lean codes are intermittent with weather/ambient air temp then most likely a faulty gasket. The fuel injector O-rings should always be replaced same time as IM gasket as those will also be hardened & losing the seal as well, resulting with lean condition all the same.
     
    Last edited: Apr 23, 2018
  6. sonic_the_hedgeh

    sonic_the_hedgeh Member

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    Yes I would use newer dextron but I need about 15 liters of dextron to change the transmission and transfer case.

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  7. sonic_the_hedgeh

    sonic_the_hedgeh Member

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    In my owners manual it specifies dextron 3 for the transmission and transfer case.

    I believe I discovered I the service records why my yukon is shifting strange.

    The was a shop and I believe the idiots topped the differentials with lube that has the limited slip in it.

    Thanks though. I can at this time only order a bucket 18.9 liters of dextron 3. Though I am going to check and see if they have dextron 6 in a bucket.

    See I noticed. My yukon denali is slightly different from the average yukon. It has 4 wheel steering.

    Owners manual says use limited slip additive in the diff for a Yukon. But with 4 wheel steering you don't use limited slip additive.

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  8. Chubbs

    Chubbs Full Access Member

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    what the hell! you have 4WS?? that's badass. people love those trucks. I would be bragging about that.
     
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  9. bottomline2000

    bottomline2000 Full Access Member

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    If your truck is 8 lug it should have a 4l80 in it. I use dex 6 in mine. It's backwards compatible but dex 3 should not be used after using dex 6.

    As far as the lean codes if it's both banks I would look at replacing the intake gasket with a quality felpro one. The truck may feel sluggish if it's leaning out from unmetered air in the intake and shift quality will suffer.

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  10. swathdiver

    swathdiver Full Access Member

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    So you've got a Quadrasteer 2500 Yukon XL Denali? Cool truck and an excellent candidate for conversion to an LBZ Duramax diesel!
     
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