Whine when drive shaft is unloaded at speed 85 300D - PeachParts Mercedes-Benz Forum

okyoureabeast · #1 04-30-2011, 05:19 PM

Hey guys, it's been awhile since I've made a post but here is a problem I am having.

I notice that when I am cruising along at any speed and I unload the drive shaft I get a very low level whine. It's really quiet and isn't distracting or startling.

When I say unload the drive shaft I mean that at say 60mph I let off the of the pedal just enough so that the car doesn't slow down or accelerate.

The noise disappears if I apply pressure to the pedal or completely release the pedal and slow down.

Where could this noise be coming from? In two weeks I will be driving cross country with my dad back to the north east so I'm trying to be attentive to any stray noises while I am driving.

smiffy6four · #2 04-30-2011, 05:28 PM

Sounds like a rear differential whine to me......

layback40 · #3 04-30-2011, 08:17 PM

Quote:

Originally Posted by smiffy6four

Sounds like a rear differential whine to me......

X2
Classic diff whine.
Just change your diff oil if you havent to make sure its ok.
They can sound like that for 100's of k miles.
Its not worth the trouble of a rebuild until you cant hear the radio over the whine.
I hope you intend on having the car up on a hoist for a good look over before you leave on your trip.

pawoSD · #4 04-30-2011, 09:46 PM

Often that whine comes from the CV axles and not the diff. On my 300E it tends to do that when coasting at higher speed, just from one side though. Very slight whine.

My brother's 300D does it too.

okyoureabeast · #5 04-30-2011, 10:28 PM

Bummer, I just changed the oil in that too when I had the differential cover off when I did the axles.

I'm going to have to find a gent in Burbank with a floor jack to remove the cover. I'll report back.

Quote:

Originally Posted by layback40

X2
Classic diff whine.
Just change your diff oil if you havent to make sure its ok.
They can sound like that for 100's of k miles.
Its not worth the trouble of a rebuild until you cant hear the radio over the whine.
I hope you intend on having the car up on a hoist for a good look over before you leave on your trip.

I had a good look after I had a new muffler installed a few weeks ago. Everything is tight so I'm not too worried, but if this noise is prevalent after a differential oil change then I guess i'll live with it. The car already has 360,000 miles on it.

charmalu · #6 05-01-2011, 12:15 AM

Funny, when I said go ahead and dive it on another thread a week or so back, I got jumped on. kind of like, who was I to say go ahead and drive it, and risk their lives with a diff that could lock up and cause an accident.

I have heard Differentials make noise also and go for many miles w/o falling out on the road.
I have also had a diff in a dump truck that just quit causing the truck to move in a forward direction, w/o making any noise.

I replaced the one in our 240. there was a rumbling sound from the back end of the car. drained the oil, and was all sparkley. pulled the cover, and the spider gear was loose and wobbly on it`s shaft. so replaced the Diff.

Charlie

layback40 · #7 05-01-2011, 05:22 AM

Quote:

Originally Posted by okyoureabeast

Bummer, I just changed the oil in that too when I had the differential cover off when I did the axles.

I'm going to have to find a gent in Burbank with a floor jack to remove the cover. I'll report back.

I had a good look after I had a new muffler installed a few weeks ago. Everything is tight so I'm not too worried, but if this noise is prevalent after a differential oil change then I guess i'll live with it. The car already has 360,000 miles on it.

As you have been in the diff recently to do the axles, all bets are off !!
No offense meant, but I hope you put the C clips in properly & the thrust washers were the correct thickness.

okyoureabeast · #8 05-01-2011, 10:21 PM

Quote:

Originally Posted by layback40

As you have been in the diff recently to do the axles, all bets are off !!
No offense meant, but I hope you put the C clips in properly & the thrust washers were the correct thickness.

I hope I put them in correctly as well, because I did the repair myself back over the Christmas season of 2009 and haven't had any major problems since then! Maybe I'm just being paranoid

I've done quite a bit of driving so maybe I'll be ok. A high mileage car is a bag of worms.

t walgamuth · #9 05-02-2011, 05:58 AM

I read somewhere that mb diffs are notoriously whiny even when new.

winmutt · #10 05-02-2011, 08:49 AM

Quote:

Originally Posted by okyoureabeast

Bummer, I just changed the oil in that too when I had the differential cover off when I did the axles.

What oil did you use? Singing or whining? Singing == carrier bearing.

okyoureabeast · #11 05-02-2011, 10:46 PM

Quote:

Originally Posted by winmutt

What oil did you use? Singing or whining? Singing == carrier bearing.

It was a synthetic gear oil if I recall correctly. I also replaced the center carrier bearing this past Christmas when I replaced my flex joints.

I'll just be attentive. I have the name and weight of the oil written down somewhere. Whatever was listed in Dmorrison"s guide for axle shaft replacement was the weight I used.

winmutt · #12 05-03-2011, 08:09 AM

Quote:

Originally Posted by okyoureabeast

It was a synthetic gear oil if I recall correctly. I also replaced the center carrier bearing this past Christmas when I replaced my flex joints.

I'll just be attentive. I have the name and weight of the oil written down somewhere. Whatever was listed in Dmorrison"s guide for axle shaft replacement was the weight I used.

You are reporting the same thing that everyone else is. Mobil 1 + 2.88 rear diff == noisy diff.

Orv · #13 05-03-2011, 01:14 PM

Most RWD cars I've owned had some form of diff whine. I'm told it comes from wear between the ring and pinion.

okyoureabeast · #14 05-03-2011, 02:33 PM

Quote:

Originally Posted by winmutt

You are reporting the same thing that everyone else is. Mobil 1 + 2.88 rear diff == noisy diff.

That's it! Mobil 1 was what I used. Should I consider changing out the oil before I start driving or just put up with it until I get home?

DeliveryValve · #15 05-03-2011, 03:18 PM

Quote:

Originally Posted by winmutt

You are reporting the same thing that everyone else is. Mobil 1 + 2.88 rear diff == noisy diff.

This is my theory on this.

I have Mobil 1 in my 2.88 for about 35,000 miles. Quite and no noises what so ever. The difference that I did, which most people will not do with an axle change, is thoroughly clean out the inside of the differential. I was able to do this easily because I had the diff out.

I believe the detergents in Mobil 1 has great cleaning ability. It will loosen up any caked on debris/dirt/contaminants that a conventional gear oil will not be able to do. So when you change out gear oil and replace it with Mobil 1, it will start to attack the contaminant and suspend it in the oil. Since there is no filter to filter out the contaminants, it has nowhere to go but to continue to circulate around the gears and causing premature wear and the sound that you hear. And it doesn't take that long for that to happen.

Mobil 1 gear oil is a great gear oil and will allow for your gears and bearings last a long time. If you're going to use it, you'll have to take precautions and thoroughly clean out the inside of the differential before filling it to make sure no detrimental contaminants gets suspended in the oil.

.