Groan, grinding sound/feel, load at 1800ish RPM

[mjwills]

Hi - I have a previous post about this, but I asked about 2 issues in previous post and want to separate this out.

2011 Yukon XL 2500. 85k miles.

At any speed (and any gear) around 1800 RPM I hear a loud wwwhhhaaaaa (if you can imagine that) and feel it in the chassis (floorboard), but a lot more on my left foot and slight vibration in wheel. Under or over that RPM it seems normal.

A dealer told me it is a groan in the exhaust, but this seems more like a drive train thing to me, like you can feel something loading up then it goes away. Could it be the front diff? Torque convertor? Flywheel or driveshaft out of balance?

Thanks!

 

[mjwills]

I stopped by a local drivetrain shop and they took her for a test spin. They said it could be the start to the carrier bearing, but want more time with it. I'm going to pull my TT with it a couple times in the coming months to see if it gets worse.

Please let me know any thoughts you have.

Thanks.

 

[CrashTestDummy]

2WD, or 4WD? If 2WD, check the front wheel bearings.

 

[992dr]

He had mentioned his front diff, I'd guess it was 4wd.

How fast are you going when this happens?
Is it during lock up in OD?

 

[CrashTestDummy]

ahh, good catch. I missed that.

 

[mjwills]

it was 2WD and sounds the same in 4WD.

I'm new to the sounds/feel of this system. I came out of a AWD Escalade. In 2WD there is still something spinning in the front diff right?

OK - now the weird thing. I only have 50 miles since I've done this, but I took my K&N out and cleaned MAF sensor and put stock filter back in. The groan is so reduced it is almost gone and seems normal noise now. Could too much oil/restriction cause a load effect of some sort and reduce flow? It seemed to have solved my rough idle as well (previous post). I'm lost.....

 

[t_bergman]

Hi - I have a previous post about this, but I asked about 2 issues in previous post and want to separate this out.

2011 Yukon XL 2500. 85k miles.

At any speed (and any gear) around 1800 RPM I hear a loud wwwhhhaaaaa (if you can imagine that) and feel it in the chassis (floorboard), but a lot more on my left foot and slight vibration in wheel. Under or over that RPM it seems normal.

A dealer told me it is a groan in the exhaust, but this seems more like a drive train thing to me, like you can feel something loading up then it goes away. Could it be the front diff? Torque convertor? Flywheel or driveshaft out of balance?

Thanks!

Have you found out what this is, I believe I have the same issue you are having and am still researching. I'm in a 09 K2500 with 70k on it. My vibration is around 1700rpm and sounds like it is coming from the exhaust, definitely from the rear right side of the vehicle.

 

[mjwills]

No I have not figured out what it is yet. It is in any gear at roughly 1800 rpm. Sound in the cabin gets louder and I feel it in the floor and steering wheel. I'm trying to ignore it... but would rather have it fixed or know if it's normal.

 

[mjwills]

Bringing this back up as it is still not solved. Since my last post, the front diff was rebuilt, changed plugs and wires and replaced rear u-joint but it made no difference. 2 dealers (went for second opinion) say the drive train is fine and both suggest motor mounts (Visual inspection they are not ripped but they could just be worn out) - went for test drive and hoist inspection. Everyone can hear and feel it, an independent shop felt it was the transfer case, but dealers disagree. I can reproduce the vibration/noise under load only, including holding brake and revving it to 1800ish RPM in drive and reverse - neutral there is nothing (which eliminates drive train except torque convertor?). Does this make sense at all? I'm no mechanic.

On a side note the latest dealer felt I have the start of a bad wheel bearing that is adding to the howl.

 

[t_bergman]

I believe I may have solved the problem with this. At least I got rid of the groan on mine. I lifted the back of the vehicle up this afternoon to see whats going on, and after feeling around I noticed that the rubber pieces which hold the exhaust assembly to the frame are worn out and allowed (in my opinion) too much movement of the exhaust. Thus some of us have been getting a groan/grinding sound around the 1800rpm range. For now, I decided to take two zip ties to bridge the small gap between the rubber and the end of the metal it sits on. If anyone knows what the part numbers of these rubber things are it would be greatly appreciated. I plan to order replacements and replace all of them.

I've attached a photo in case my explanation isn't quite clear.