1200 RPM Hum

Discussion in 'LR4' started by Bailey123, Jun 6, 2019.

  1. Bailey123

    Bailey123 New Member

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    Has anyone experienced a hum or vibration at 1200 to 1300 RPM in their 16 LR4 V6 super charged? Is it a torque converter imbalance or could it be the snout on the super charger? Any help would be appreciated.
     
  2. backcountryLR4

    backcountryLR4 Full Access Member

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    Yep, I have the same thing which is very annoying and noticeable at normal driving speeds around town. Took it in to the dealer and described the issue in great detail and after they drove it around they said it sounds like all the other SCV6s they have driven and noticed nothing wrong. Still annoying but I do notice it less after 2+ years.
     
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  3. Bailey123

    Bailey123 New Member

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    I did some research and found a transmission additive called "Dr. Tranny" others have used in other makes of automobiles to stop torque converter imbalance issues and would like to see if it solves this issue. Unfortunately the LR4 doesn't have a transmission dip stick/ fill tube and you have to get to the oil pan on the transmission to add it. You need to jack up the vehicle, remove the skid plate just to get to the underside of the transmission as you would if you were changing the fluid. If I only had my own garage with a vehicle lift. Any suggestions?
     
  4. scott schmerge

    scott schmerge Full Access Member

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    Not true. You can add it from underneath with the truck on the ground. I’ve done it...

    Easy procedure. I’d do it on an unlevel surface with the passenger side uphill and while the vehicle is cold (transmission fluid expands as it heats). Remove the fill plug on the side of the transmission (it’s not under the skid plate) and squeeze in a tube of dr trannys.

    What you are describing does not sound like torque converter shudder though. Dr Trannys is a friction modifier and helps worn clutch plates grip better. I do not know if it would help with an “imbalance”.

    Dr trannys is an additive and shouldn’t do harm, but if I were in your shoes, I’d first do a transmission fluid drain, filter, and fill before I resort to dr trannys.
     
  5. ktm525

    ktm525 Full Access Member

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    Does it occur in all gears (ie varying speeds)? If so then I wouldn't be looking at the transmission. You know if LR could dith the supercharger and add a couple more pistons that may cure the issue. I think it would fit too.
     
  6. jlglr4

    jlglr4 New Member

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    This could be the transmission heat sheild bracket. The hum or vibration is metallic sounding, happens only under light load and in gear (not when in park and just revving). You might be able to get it to rattle on a brake torque. There is a TSB on this problem.

    It starts out as a hardly noticible rattle, but will eventually get worse. I just had mine fixed - basically had to tell the tech exactly what to check. He took a ride with me and I was able to reproduce it on a brake torque, but just barely. The tech riding with me was already familiar with the problem, but still wanted to hear it to confirm.

    Note that the heat sheild itself is not loose. It’s a crack in the bracket that holds the heat shield. So, if you crawl under your truck and try to rattle the heat shield, it will feel solid. But, at least on mine, if I pounded the heat shield with my hand a few times pretty hard, it would start to make a humming sound with the vibration.

    Good luck with this.
     
  7. Frank8

    Frank8 Full Access Member

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    I think this has just started on mine at 25k miles.
    Backed out of the garage on Monday and noticed it at about 1300-1400 rpm.
    I could reproduce it by revving up from idle.
    Car is in a lot in NYC for the week so I don’t know if it still does it but will check when I drive home.
     
  8. avslash

    avslash Full Access Member

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    I don't have the TSB handy, but there is also a know vibration issue with the transfer case.

    The fix is to screw a factory damper into a threaded hole that already exists on the transfer case.

    Google LR4+transfer case+damper and you will likely find what I am talking about.
     
  9. jlglr4

    jlglr4 New Member

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    The TSB on the heat shield bracket problem is LTB01207NAS1. You can pull it off the NHTSA website. Service tech told me the hallmark is that rattle right at 1200-1300 rpms.
     
  10. BeemerNut

    BeemerNut Full Access Member

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    That's the best answer, I second your reply......~~=o&o>......
     

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