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2009 E350 Mercedes High pitched noise coming from rear of car

Hello All,

First time here,

I have a 118k Mile 2009 E350 recently I’ve had a noise coming from the rear of the car, this started off very quietly but progressed to a decent volume, I’ve replaced the rear bearings on both sides, this made the noise ALMOST go away … for about 2 days then it returned.
Any other ideas of things that I should check?

Details about the noise :

Changes volume and pitch only based on the speed of the car, putting it into neutral whilst at speed makes no difference to noise at all, there’s no change as it shifts through the gears. Purely related to speed.
For the level of noise reference, at 70 mph it sounds like you’re holding 3500 Rpm or so.
As mentioned I put new wheel bearings on the rear and it came back after only 2 days.

I appreciate any input or suggestions.


Does the sound change at all when you press the brake pedal?

Rear differential whine, maybe. Check the fluid level, check the magnetic fill plug for trash, then drain it and search for metallic bits. Inspect the gears for wear, bearings for free play, refill and cross your fingers it goes away.

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Good ideas above. I’m guessing either the differential fluid level is low or the wrong spec, or a problem with the rear brakes. If the rear differential fluid level is now low or has ever been low for an extended time, given the wheel bearing clue, you may be looking at needing a major rear axle service job.

It could be as simple as old and noisey tires

This has fooled many people into replacing parts needlessly

How old are the tires, and how much tread depth is remaining . . . ?!


No it doesn’t.

Rear tires are pretty warn, I’m going to estimate they’ve done about 20k miles. Still look in decent shape but yes the noise is pretty extreme though, I suppose it could be tire related but I’d be very very surprised if it caused this much noise.

It started probably when I had about 10k miles on the tires only so It would be pretty crappy if it was the cause of it.

I’m going to take a look at the diff fluid asap yes.


did you have a shop do the rear bearings? noise went away. alot? and came back. hmm,

How old are the tires . . . ?

What brand . . . ?

I hate to say it, but if they’re Firestone, and they’re already a few years old . . . that might very well be the cause of the noise

I’m speaking from some experience here . . .

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Tires definitely less than 2 years old maybe 20-22k miles tops

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thanks for the information

Exactly. My Toyota Celica was making noises in the rear. I thought I was looking at a worn pinion or ring gear in the differential. It was time to rotate tires, after I got done, noise was coming from the front!

Unfortunately I can’t rotate the tires front / back. 2 difference sizes