Highway drone and loud idle?

[Skydance]

I did the same and it helped but still bothers me.

Hopefully, you will find it after a while. Took me a couple of weeks trial and error. Have you checked out the section where the spinning drive shaft is and where the sides meet the fuel tank towards the rear?

 

[255/85]

The 8:55 mark in this video I found seems to capture the drone sound pretty well. Hate it.

The drone in the video sounds very much like an exhaust issue and engine RPM related. I can't read the tach but the sound disappears the moment the vehicle upshifts to eighth gear and the revs drop. That rules out the transfer case.

@Jiman01 - I'm not sure he comes off the throttle. Maybe a little but the tranny does shift up.

 

[Chadd7]

Hopefully, you will find it after a while. Took me a couple of weeks trial and error. Have you checked out the section where the spinning drive shaft is and where the sides meet the fuel tank towards the rear?

I did all that. Improved but I still hear it. Only thing I haven't tried is taking the rear skid plate off. suspect there may be some loose areas of the heat shield. Possibly under the front skid plate too.

 

[SkiBum1]

The 8:55 mark in this video I found seems to capture the drone sound pretty well. Hate it.

View: https://www.youtube.com/watch?v=iI_ij82Ylxs&t=553s

I am not sure I hear anything other than off road type tire drone sounds. I’ll bet it’s the tires and nothing with the ineos. Also, crank some tunes man! Why are you driving without music, are you insane!

 

[Chadd7]

I am not sure I hear anything other than off road type tire drone sounds. I’ll bet it’s the tires and nothing with the ineos. Also, crank some tunes man! Why are you driving without music, are you insane!

Appreciate you chiming in, but I think we all know the difference. And yes, my main point is that I can't hear my music because of the noise!

 

[Tom109]

I have not noticed any drone, beyond normal variations of load + throttle position. I do occasionally have some vibrations from below, but preliminary inspections show my heat shielding is pretty tight.

 

[Skydance]

I did all that. Improved but I still hear it. Only thing I haven't tried is taking the rear skid plate off. suspect there may be some loose areas of the heat shield. Possibly under the front skid plate too.

Let us know how how it goes

 

[Chadd7]

I took a loaner Grenadier today because of the prolonged wait for a transfer case seal to be delivered. It has the same drone as my Gren. Seems like it's just a thing we need to live with.

 

[Tom109]

I took a loaner Grenadier today because of the prolonged wait for a transfer case seal to be delivered. It has the same drone as my Gren. Seems like it's just a thing we need to live with.

I think it will be possible to “tune” some of the shielding, but my free time is evenings and early AM when it’s been 14deg.F

I’ll get around to it.

 

[Chadd7]

I think it will be possible to “tune” some of the shielding, but my free time is evenings and early AM when it’s been 14deg.F

I’ll get around to it.

Agreed. For some reason, this loaner vehicle's stop/start doesn't work hehe. And the loud-ish idle is the exact same as mine. Other than that, drives identically and this one is on Bridgestones too, but 17s.

 

[klarie]

When I received my Grenadier in October 23 I did not notice such a drone. However it appears now since 3 to 4 weeks. However he had a couple of offroad rides including passing over some tree branches and wooden stuff on the ground. I think some stuff is sticking there .. and perhaps I need to bend some heat shield or what ever is there in the underbody. Next days Ole the Grenadier gets a proper wash and then I will have a look at it.

 

[zvakanaka]

Exhaust drone noise at speed. Noticed that on my way home from the dealer in Clearwater FL. 70-80 MPH foot lightly on the gas to keep up the speed, lift foot off drone noise gone. Not an issue around town however.

Good friend of mine who worked for both Toyota and Honda in QC, says its harmonic distortion caused by the exhaust gasses traveling through the pipes on our Grenadiers and it's not an uncommon problem in the industry. In our cars it seems to manifest itself around 2000 RPM as many have noted. The solution appears to be adding a welded steel gusset plate at the appropriate location on the exhaust's exterior but no doubt requires engineering to determine the exact location and the size of the plate needed. Apparently GM first used magnets and moving them along the exhaust until they determined where the distortion was originating, then welded an extra gusset plate in that area, problem solved.

 

[Chadd7]

Good friend of mine who worked for both Toyota and Honda in QC, says its harmonic distortion caused by the exhaust gasses traveling through the pipes on our Grenadiers and it's not an uncommon problem in the industry. In our cars it seems to manifest itself around 2000 RPM as many have noted. The solution appears to be adding a welded steel gusset plate at the appropriate location on the exhaust's exterior but no doubt requires engineering to determine the exact location and the size of the plate needed. Apparently GM first used magnets and moving them along the exhaust until they determined where the distortion was originating, then welded an extra gusset plate in that area, problem solved.

Do you plan to try this fix?

 

[Tom109]

Do you plan to try this fix?

I have some big magnets.

 

[Chadd7]

I have some big magnets.

haha. I'd like zvakanaka to try this first, since he has an expert friend. Just sayin'

 

[zvakanaka]

I have some big magnets.

Actually the drumming in my car doesn't seem too bad and doesn't bother me really, not enough at least to borrow you magnets.

 

[Skydance]

Sorry to resurrect this post again. Has anyone with this issue actually been fixed. Mines in for a service and the courtesy car (diesel) has the same resonance drone at 65 mph (around 1800rpm). I’ve had a go with all the heat shields under the car with no luck. I thought I fixed it but it drones at cruising speed 65mph and it’s not the heat shields.

 

[Lord Ripon USA]

Sorry to resurrect this post again. Has anyone with this issue actually been fixed. Mines in for a service and the courtesy car (diesel) has the same resonance drone at 65 mph (around 1800rpm). I’ve had a go with all the heat shields under the car with no luck. I thought I fixed it but it drones at cruising speed 65mph and it’s not the heat shields.

Take them all off while the screws are still rust free.
Drive the car at the normal speed of resonance.
Put them back on one at a time.
Id the resonant culprit, make mods accordingly.

Have the whole world consider you a genius and get free beer from thankful Grennie owners world wide for being that guy.

 

[DaveB]

Thanks. I did read that thread before creating my own. For the highway drone, I really think the sound is coming from the exhaust. I wonder if some modification can be made to eliminate it. It's really annoying.

There is a dial on the centre instrument stack or alternately a couple of buttons on the steering wheel.
They allow you to turn the music up and cover the sound.
Another option is to open the safari windows and the wind noise will drown out the sound.

 

[Chadd7]

There is a dial on the centre instrument stack or alternately a couple of buttons on the steering wheel.
They allow you to turn the music up and cover the sound.
Another option is to open the safari windows and the wind noise will drown out the sound.

Thanks. I believe the noise was coming from a leaky transfer case seal. Ever since I had it replaced, no more drone.