Humming or harmonic noise in 4 wheel drive

[Mikep123456]

Anyone experience any type humming or harmonic type noise while cruising? I noticed it mostly when I’m on snow covered roads when it goes from drifted, unplowed to hard pack. Normally around the 4200 rpm range. As soon as the road returns to loose snow it will go away or if I drop the rpms. Sometimes I think it’s the tires humming but I switch off the 4 WD and it stops after it disengages. Not sure what it would sound like in sand or loose dirt at same speed or rpm’s. FWIW 2020 HD10 Limited 

Thanks for any help. 

 

[Hkb82]

It sounds like tire or snow build up issues to me but as you stated taking it out of 4x4 and sound stopping would make me think it’s something inside. I’d try and find some bare roads on a nice sunny day and see if it will make the sounds without snow. Easy way to eliminate snow conditions. If it’s not road conditions or even before that I’d dbl check fluids/grease and hardware.  I’m sure some added noise might occur if I’m running in 4x4 vs 2x4 with my 19 hd10 nothing I’d call excessive humming or harmonic. I’m no pro though. I have a tendency to be able to hear those small non normal new sounds or as I call it the beginning of the end and usually if it’s super hard to track down I have to let it get worse before I can find the prob.  In your case I’d be playing hard the next couple rides and if it pops letting warranty cover.  

 

[Mikep123456]

Thanks for the reply. I also thought it was snow build up but like you ...when I’m in loose snow I don’t hear it. It almost seems like it’s the tires I hear and it’s louder because they have power to the wheels? Not sure if that makes sense. 

 

[Andystoy19]

I have a 2019 Defender XT Cab Hd10 and I noticed a vibration when I test drove it at home, took it back and had the shop foreman ride around with me and he assured me that everything was normal.

I had put my 30" Cryptids on brand new so that to me may have been where some of the vibration comes from but I was ice fishing this weekend in knee deep snow and the vibration was there (4100 to 4700 RPM) so I am sure its not added to by the tires. 

I suspect that there is a harmonic in the power train (engine, gear box and front and rear drive) that was not adequately dampened by the engineers so I don't even pay attention to it now although it is strong enough that you can hear and feel it in the cab.

If you say that disengaging 4x4 reduces it that would narrow it down to the gear box, and front drive?

 

[Mikep123456]

Thanks for the reply. I’m thinking front gear box as well. I’m taking it in next week to have the dealer investigate. 

 

[Pace31]

Did you get an answer from the dealer? I have the same thing happening with mine.

 

[Mikep123456]

No, what year is your Defender? What do you think it is?

 

[Pace31]

Mine is a 2021. I had a 2018 and it did not do it. Its strange how it seems connected to RPM's and snow cover. Did the dealer have any feedback? I am going to do a lot of riding with it over the holidays on frozen lakes so hopefully I can narrow it down.

 

[Mikep123456]

Pace Your description fits my experience perfectly. Almost as if it goes away under some form a resistance like snow cover on the road then reappears on hardback. I’m not sure my dealer has the proper grounds to experience it. I may bring it in after the holidays.