Hey all!

i just purchased a 2014 E550 4Matic that’s been CPO’d. On the long drive home (8 hours) I started to notice a few things as I played with the vehicle. I did a search on these and couldn’t find anything so hoping others out there have experienced the same issues. Find it odd that it’s CPO’d and these were not caught before.

1. Between 85-95 MPH, you can hear a quite audible hum coming from the front of the car. It’s only while cruising with minimal throttle input. When I add more throttle response—when I hear the exhaust specifically—the sound goes away.

2. Also starting at 90MPH, the car tends to vibrate quite a bit. Not to the point of unsafe behavior, but noticeable enough to annoy you!

3. I just noticed this today while giving a friend a ride. Sometimes in 2nd gear very close to redline, a loud whining noise—like a supercharger—occurs for a second before the upshift occurs.

Anyone ever heard of these issues? Other than these, this car is great!!

1,2 either tires out of balance or bent wheel. 3, probably a bad pulley. It’s a CPO, so take it back. I doubt the tech did many jumps to redline so go easy on them. My 2014 E550 4Matic does not exhibit that behavior.

I would heavily lean towards a bent rim. Mine had this problem as well, especially the humming/dull groaning noise like a really really fast vibration. I had two bent rims, one in particular that was pretty bad. I suspect you have the amg rims? My understanding is they’re not forged so they tend to bend. Good and bad there I guess. Easy to bend (instead of crack) but easy to bend back. When I bought my 14 CPO last year, the sales guy was strongly warning me to get the tire and wheel package that covers them for 5 years unlimited miles. I did, and he was right.

normally I’d just say likely balance issue possibly tires as well, and very well could be. But on these cars, you can’t ignore the rims as easily as on other cars. I have a 15 VW GTI as well, 18 inch wheels low profile tires. Those are forged wheels, never a problem.

depending where you live, likely a few places that can fix them for maybe $150 per wheel if that much. Dealer can fix it too, but if given excuse of wheels not covered by CPO warranty (they may not) you don’t have to pay dealer prices for the fix. They just hire out to a wheel company locally who typically has a few dealerships on their client list. Just go direct and avoid the dealer tag-on markup.

Thanks for the info all!

The vibrations have now increased to pretty much all the time. The ride used to be super smooth on our road—paved only a few months ago. Now you can feel just about everything while even at low speeds.

A few few more things have popped up in the process too:
- Vibration while accelerating, deceleration and braking at any speed really.
- Now car lunges when going into drive, reverse and especially park—used to not ever feels this.
- Sputters while in neutral, park and consistent throttle while driving (you can see the tac move too)
- Ac is fluctuating

I purchased the car unfortunately 500 miles away, so taking it back to the dealer is very impractical. But, I’ll be taking it to my local dealer after chatting with the place I purchased it from. Really hoping that everything will be found...

Im thinking the same thing now. The idea of a bearing, as well as motor mounts make a lot of sense. I checked over the tires and couldn’t see anything to the visible eye but who knows. It doesn’t sound like it’s a singular issue anymore either—probably a few things all piled up on each other. If it ends up being anything outside of CPO warranty, it sounds like the dealer I purchased it from will be paying for it which is not only great news, but the right thing to do since it was supposedly inspected thoroughly during the CPO certification.

Ill definitely be making updates as they come. I’ll be dropping the car off next Wednesday and will hopefully have updates soon after!

I suggested a pulley due to the High whining noise near redline. Most drivers of these cars never see anything within 3,000 rpms of redline. Take it back

For sure! For that particular issue, I’m thinking the same as well.

this has been so helpful! Thanks so much!