Differential humming at steady speeds?

[imautoparts]

Hi all,

Just did a search for an odd unpleasant humming that has begun to occur at 30 - 35 mph on my 1999 C280. Seems that others have experienced this due to failure to change the differential oil regularly.

Two questions:

1. What oil or oil+additive do you recommend to service the differential on a car with 144K miles?

2. Is there any way to eliminate the humming or will I have to live with it from now on?

[202brabus]

Your diff is trash, source another one, cheap from a junk yard.

[96mbc280]

I did change my differential fluid @ 173k miles for the first time , did have a very very low humming noise ,It did make a difference after I changed the fluid , try that , I used valvoline sae 80w-90 high performance gear oil from Autozone

[John Jones Jr.]

Drive on, if you can live with the slight humming as it's very unlikely the diff will break up. Otherwise, buy a set of bearings & seals and have them fitted, not that expensive if you don't buy the from the Stealers.

[imautoparts]

I did change my differential fluid @ 173k miles for the first time , did have a very very low humming noise ,It did make a difference after I changed the fluid , try that , I used valvoline sae 80w-90 high performance gear oil from Autozone

I couldn't live with knowing the hum was due to low or worn out fluid, so literally the next morning after I discovered the problem I went to my local Firestone dealer and had the fluid drained and changed. I would have done it myself with full-synthetic but to my dismay discovered how deep Mercedes tucked the center section into the underbody tunnel - without a pump and hose to lift the fluid up and in there was no way to squirt fluid into the diff.

Noise hasn't completely stopped but it has abated. It is most noticeable if I've driven fast enough to reach 4th gear and then slow down to 28-30 mph.... If I then drive at a steady speed I can still here a bit of a moan with the windows up. It may be my imagination but it doesn't sound as bad - at least I hope I'm no longer grinding material off the gears.

[timmyj51]

Probably will have to live with it. Nothing wrong with the diff; it will still function fine.
Paying the price for not changing your diff fluid regularly. Could get a used one but it
may not be much better than what you've got. Might try a heavier weight fluid to muffle
the hum.

[John Jones Jr.]

without a pump and hose to lift the fluid up and in there was no way to squirt fluid into the diff.

You can do it yourself using a length of 10mm clear hose with a funnel inserted in one end. Same goes for manual gearboxes too.

[vaspen]

sound like to me time for some tourqy gears to be swaped in there :3

[202brabus]

You can run it but eventually it will go out, ive seen it several times before. It will just get louder and louder. If you want to use some mechanic in a can, go for it. Or you can do it the right way.