Differential, transfer case, driveshaft ... Your guess?

[Primetime]

Hope everyone is having a lovely holiday season. I mentioned in another thread that I purchased a 2010 with 41,000 miles on it. I didn’t notice during the test drive, but there is a whine/hum in the driveline. It is only there when I am in drive, and I either give her a decent amount of gas (at least 1/3 throttle) or I am going uphill. I thought it may be the attached TSB from another thread so I installed the transfer case damper associated with it, but that turned out to not be the issue. The YouTube video below is after I installed the damper. I am driving up a steep hill with my phone laying in the driver’s side footwell close to the console recording the video. The clip begins with me at a standstill, and I slowly increase throttle until about 3k. The high pitch whine comes into play somewhere in the 2200-2500 rpm range. I am waiting on transfer case/differential fluid to be delivered so I can do a change on them and look closely at the current fluids for metal. Does anyone know the problem off the top of their head? Any help will be appreciated.

http://australiancar.reviews/_pdfs/SB-10069796-0699.pdf

 

[Quijote]

I am by no means an expert, but based on the narrow rpm range, the the sound, it seems to be a resonance frequency.

Does it happen in all gears at that rpm? It should be straight-forward to find out if it is mph-specific or rpm-specific.

 

[Primetime]

It does make noise in all gears based on how hard I hit the gas. It is not speed related. Cruising around like of the highway is quiet. It’s only when I accelerate or I’m going up a steep incline causing the truck to work hard

 

[Quijote]

If that is the case, then it reinforces my belief that it is a resonance issue. Hard to tell from the video, but it seems like it's something external. Perhaps a metallic heat shield or something of the sort that is not tightened down or barely touching something and a particular amount of load is causing flex or a frequency that cause a part to vibrate.

Is it more audible with the windows down? I would see if I can get a mike under the car and see if it can pick it up. I would chase that down first.

If that sound came from inside an oiled system, that would be a bit worrisome.

I'd:

1) Try to nail down if it is an external vibration issue or not.

2) Flush drive train fluids. Probably not a bad idea anyway, since you don't know how it was used. They may have towed/off-roaded a lot with it. (???)

Go from there.

 

[Primetime]

In another thread Jaguardoc504 said that what I was describing sounded like the carrier bearing. I did some research and found a few videos of other cars with “failing” but not failed bearings that made the same noise. I got under the truck and moved the rear driveshaft around and there is play. I am only using one hand to move the prop as I videotape. Also the noises you hear are my hand on the metal not coming from the metal itself, however if you listen closely you can hear a “squishing” coming from the rubber around the bearing. Can anyone with a good working carrier bearing confirm if this is normal movement. I would assume that there should be some play but mine seems a little excessive.

 

[Rex Rekstad]

The fact that the noise only appears under load screams bearing. Sometimes you just need to let them get bad enough before you can feel the play.

 

[Juanrs]

In another thread Jaguardoc504 said that what I was describing sounded like the carrier bearing. I did some research and found a few videos of other cars with “failing” but not failed bearings that made the same noise. I got under the truck and moved the rear driveshaft around and there is play. I am only using one hand to move the prop as I videotape. Also the noises you hear are my hand on the metal not coming from the metal itself, however if you listen closely you can hear a “squishing” coming from the rubber around the bearing. Can anyone with a good working carrier bearing confirm if this is normal movement. I would assume that there should be some play but mine seems a little excessive.

Mine moves that much, maybe more, but I have an LR3 and I also have a strange thumping noise under light load that I can't find. While driving the noise suddenly stops and the car veers to the left, leading me to believe it's the differential.

 

[Kenneth Kahan]

I've heard sounds like that and they are related to exhaust flow. You may have a catalytic converter or muffler that is coming apart inside and at the right air pressure creates a resonance just like air howling around a building or what you hear from the front grill on some cars.

 

[Robin Parsons]

If you know someone with a chassis dynamometer (4 wheel) it should be easy to find.

 

[BikePilot]

There's a tsb to add a weight to the transfer case to solve a problem described like this. Some sort of resonance thing with vibration of the trans/transfer case.