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Noise + Golden Glitter in my Gear Oil. ***FIXED***
I have a mystery bearing-type noise when driving at interstate speed (70-80MPH). It's a rhythmic nom-nom-nom sound. The tempo of that rhythm increases during right hand turns in that same speed range.
TLDR UPDATE:
I replaced the noisy right front hub assembly and the noise is gone.
The pinion bearing in the diff is also noisy when listening with the stethoscope or chassis ear, but it's not THE noise. I'll be shopping around for a complete LSD.
This is a 2008 with the open differential.
I have run the car with the wheels off the ground up to some speed (exact speed unknown since I was not aware of dyno mode at the time) and listened at both rear knuckles with a stethoscope. I heard nothing at all from either side. I may not have had it going fast enough to hit the speed where I hear it inside the car, but it should have been more than enough to hear it with the stethoscope.
Listening to the diff near the pinion bearings, I heard some noise. Not the same noise that I hear in the car, unfortunately, but definitely noisy compared to the rear wheel bearings, which were silent.
I would love to figure out a way to spin the front wheels up to speed, since I was not entirely satisfied that the diff noise was THE noise.
I will try it again in dyno mode at highway speed and see if it starts sounding like it usually does from the driver's seat.
Today I replaced the gear oil, and found what I consider to be a lot of metal in the fluid that I drained out (see pic). I haven't driven the car yet since doing the fluid. I'm hoping for a slim chance that getting rid of the glitter juice and getting fresh fluid into it helps with the noise, but we'll see how that goes.
I've searched quite a bit and found threads regarding diff noises, but most seem to be hearing noise at low speed, and most of those noises seem to be whines or clicking.
Has anyone dealt with a noise like the one I've described here?
Last edited by AMGSIXTHREE; Aug 17, 2022 at 01:08 PM.
2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
Wheel bearings should be maintenance items. Mine were abused and subjected to super high temps, and were terrible when I replaced at 35k miles. I heard noise and felt binding at low speeds.
It's likely your tires or left front wheel bearing
I suspected tires initially, but there is zero change in the noise between completely different road surfaces. For example, going from brand new asphalt to gritty concrete, the bearing noise stays exactly the same. And at that same time I can hear the tire sound changing normally across the two surfaces.
If anyone has an idea for spinning the front wheels up to highway speed on jack stands I'm all ears. I considered building some kind of attachment for my impact gun to spin it from the tire...
I suspected tires initially, but there is zero change in the noise between completely different road surfaces. For example, going from brand new asphalt to gritty concrete, the bearing noise stays exactly the same. And at that same time I can hear the tire sound changing normally across the two surfaces.
If anyone has an idea for spinning the front wheels up to highway speed on jack stands I'm all ears. I considered building some kind of attachment for my impact gun to spin it from the tire...
You're not going to put the load of a car on it anyways so whats the point? Wheel bearings make noise with more vertical load added, but massively more noise with lateral load, your driving "test" has already pointed in that direction, now check them properly.
You're not going to put the load of a car on it anyways so whats the point? Wheel bearings make noise with more vertical load added, but massively more noise with lateral load, your driving "test" has already pointed in that direction, now check them properly.
Just Google "how to check for wheel bearing play"
lol I am well familiar with checking bearing play. There is zero play. And the noise is present without putting additional load on one side or the other.
Bearings usually don't need to be loaded to check for noise. With wheel bearings, we typically start by driving the car in the air and listen to them, unloaded, with a stethoscope. Which I have done with the rear.
I would love to get the wheel up to speed to check it, but that's not possible in front. I'll check it the old fashioned way, with the caliper and rotor removed, and see how it feels by hand.
The point of the thread was to ask if anyone had dealt with the noise that I've described, and had found a similar concern with the metal in the gear oil.
Update:
I checked both front wheel bearings today and they are both noisy when turning by hand.
I'm gonna go ahead and replace those to start. Will update once that's done.
If your front wheel hubs/bearings are at all noisy or binding, they need to be changed anyway regardless of what else you might find.
Agreed, but I don't have an unlimited budget. If they're noisy with a stethoscope but silent in the car, and I have some other bearing that I can hear over the radio, I want to address the big one first.
The front hub assemblies will get done either way for sure. I'm hoping they are the culprit, since they're quite a bit cheaper and a little easier than a diff.
Being quiet while under the car at slow speed and no load would be considerably louder at speed and with load
They were actually pretty noisy just spinning them by hand and getting maybe one revolution out of them. I'm pretty sure that's going to be the big noise. We'll see what the ChassisEar reveals.
Im going to go with bent wheels. You should be able to spin them by hand fast enough to see if the inner barrel is out of round. The tires may still balance but the wheel is no longer round and thus the tires wont be round. What is your current wheel and tire setup? brands? etc.. Tire brand / model makes a big difference as does the wear pattern. It should be pretty obvious to determine if the noise if from the front or the rear of the car. Wheel bearings on these are very uncommon unless you get into an accident or hit a curb.
As for the Differential fluid - I doubt it was changed ever because on non-lsd cars don't have an interval. using the term "Gear" maybe misunderstood at gearbox aka transmission vs differential / rear drive gear. Id say that fluid looks normal if the diff fluid hasn't been changed regularly or ever. Smell is a good indicator of how fresh it is too. Did it smell pretty bad? then it's not 20k old. Transmission service is due at 30-40k depending on mct vs torque converter.
Im going to go with bent wheels. You should be able to spin them by hand fast enough to see if the inner barrel is out of round. The tires may still balance but the wheel is no longer round and thus the tires wont be round. What is your current wheel and tire setup? brands? etc.. Tire brand / model makes a big difference as does the wear pattern. It should be pretty obvious to determine if the noise if from the front or the rear of the car. Wheel bearings on these are very uncommon unless you get into an accident or hit a curb.
As for the Differential fluid - I doubt it was changed ever because on non-lsd cars don't have an interval. using the term "Gear" maybe misunderstood at gearbox aka transmission vs differential / rear drive gear. Id say that fluid looks normal if the diff fluid hasn't been changed regularly or ever. Smell is a good indicator of how fresh it is too. Did it smell pretty bad? then it's not 20k old. Transmission service is due at 30-40k depending on mct vs torque converter.
The gear oil smelled fine, but had a lot of metal in it. The carfax shows a major service at a Benz dealer at 58K, and both "differential service" and "transmission service" are itemized in that record. It seems unlikely that a MB dealership service department would falsify a service record, or that a Benz tech would skip the gear oil on a major service. But stranger things have happened.
If you read through my earlier posts, I've mentioned that the noise does not change one bit when the road surface changes, and that I can hear the tire noise change while the "bearing" noise remains constant.
The wheels are stock. Tires are Vredestein bull****, which would be my first suspect were it not for the circumstances mentioned above. Also, the car is quiet up to around 70MPH. In my experience noisy tires are noisy all the time.
I'll keep the bent wheels in mind, though.
My ChassisEar should be here tomorrow. I'll update when I have results.
Yea, i doubt they would falsify a record, I was just clarifying because the terminology and service records they use on vmi's is very crude. If it says transmission and diff you're good to go.. It's just unusual for them to do rear differential service. Most of the techs or owners didn't know about the LSD diff intervals, much less smart enough to change it ever on regular differentials. So that's nice they did that. Being that it was done so recently there should be no metal shavings at all. Im going to say diff is probably toast.
The gear oil smelled fine, but had a lot of metal in it. The carfax shows a major service at a Benz dealer at 58K, and both "differential service" and "transmission service" are itemized in that record. It seems unlikely that a MB dealership service department would falsify a service record, or that a Benz tech would skip the gear oil on a major service. But stranger things have happened.
If you read through my earlier posts, I've mentioned that the noise does not change one bit when the road surface changes, and that I can hear the tire noise change while the "bearing" noise remains constant.
The wheels are stock. Tires are Vredestein bull****, which would be my first suspect were it not for the circumstances mentioned above. Also, the car is quiet up to around 70MPH. In my experience noisy tires are noisy all the time.
I'll keep the bent wheels in mind, though.
My ChassisEar should be here tomorrow. I'll update when I have results.
Dose the sound have any relation to the gears and rpm? If it's quite up to 70mph, it could be that 7th gear is bad? Just thinking due to the condition of the gear oil.
Dose the sound have any relation to the gears and rpm? If it's quite up to 70mph, it could be that 7th gear is bad? Just thinking due to the condition of the gear oil.
I hope not. I'll try it and see what it does in 6th, 5th, etc.
Tested with the ChassisEar today. The only thing making anything like the noise I hear in the car is the right front wheel bearing. It is loud as ***** and obviously wasted. The left front wheel bearing is quiet.
The Ear confirmed what I found with the stethoscope running the car on jack stands. The rear wheel bearings are quiet, and the pinion bearing in the diff is screaming. It's a high-pitched scream and not at all rhythmic. So unless the ChassisEar is completely missing the deeper tones AND the rhythm, I don't believe that's my noise.
The transmission and driveshaft center support bearing are also quiet (for this noise) and I did confirm that the noise is present and does not change when shifting down to 6th at the same speeds.
I ordered a right front hub/bearing assembly and I'll start with that.
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