Hum & Rumble

[Aequitas1916]

Hello all,

 

Sorry for the book below.

 

I have a 2017 Silverado 1500 double cab Custom with 5.3L and manual 4x4. I have aftermarket steel wheels with 33" AT tires and a slight suspension lift of 1" with Bilstein 5100s. I also carry a fair amount of camping gear. So, I'm asking a lot of this truck.

 

The first major repair I had was at 90k, when my transmission started getting rough, and the magnetic plug was covered in spikes of metal shavings. I warrantied that and got a new one, but it seemed super early for that.

 

Fast forward 30k miles. I started living on the road in February. I'm towing a small travel trailer (21' overall). I've put on about another 15k miles in that time (135k total now), so I expect things will need fixed/replaced. Everything seemed fine until April. First I had to replace a CV axle. No big deal. Next was an exhaust leak caused by a busted exhaust manifold bolt. Mechanic said this is pretty common for the 5.3. My brother in law is in auto parts and has the same truck, and said he heard that happens when engine mounts start going, causing things to be misaligned. Anyway, I got that fixed. But I started to notice a hum that I couldn't figure out. It was a separate sound from the hum of the AT tires. I also started feeling a kind of rumbling vibration under my feet. So I took it to a shop on the road. They pulled the plug on the transfer case and it's covered in metal. I couldn't afford the price tag or the wait for a brand new case, so I took it back home and had a trusted mechanic put in a used one that had roundabout 35k on it.

 

Things seemed fine for about 800mi. Now I've got a hum again. Seems a lot more noticeable when I'm towing vs when I'm not. Also seems to go away when coasting vs accelerating/cruising. I've been to 3 different mechanics, including a Chevy dealer. All of them said the diffs, the transfer case, u joint and transmission are fine, although the dealer said the trans fluid seemed dark so I had them do a flush and fill. The rumbling vibration under my feet never went away, though nobody but me seems to notice it because I know my truck and they don't. The dealer said it should be fine and noises like that are normal for a truck with this many miles. But I take care of my truck and people have trucks that run 2-300k+. So something is causing it.

 

My tires have some cupping, but I expect that would cause constant noise vs dying down when coasting. Any ideas on the hum?

 

As far as the rumbling under my feet, could that be suspension parts? Or a return of the exhaust leak? 

 

I'm at my wits end with this. I'm 2,000 miles from home and have lost confidence in the truck I love.

 

Thanks!