The determination of "differential" or "wheel bearing" can be assisted if the following question can be answered:

Does the noise almost go away entirely when the drive shaft is unloaded?

The drive shaft is unloaded when you are cruising along at a steady speed and you lift your right foot ever so slightly so that the vehicle just begins to slow down. If you lift too far, the shaft will load up in the opposite direction and the noise may return.

Please attempt to reduce or eliminate the noise via your right foot, in the manner described, and report back.

When traveling at a steady rate any where from 40-65mph I get a high pitched noise. When I let off the fuel pedal the sound goes away and depress again and it returns. Is this bad wheel bearing? have something to do with drive shaft, differential?? Differential fluid has been changed, rear axles are new, rear brakes are new. This is my first post by the way.

heh... as of right now the car in question has been sitting for almost a year now... the water pump and t-stat need to be replaced and i have not had the time/money to do that, and i'm betting the fuel tank has a ton of algae growing it in now as well.

as far as the whine goes... i know it isn't the wheel bearings, and based on the old bimmer i'm driving now that has the exact same whine and has been officially diagnosed by a BMW specialist as a bad differential, i'm pretty sure that's the problem. i'm sick of trying to get rid of that damn whine though... i've done TWO diff swaps on her (they were both used, from silver star recycling), and the whine sounded slightly different with each swap. just my luck to a) buy two german cars with bad differentials (NEVER heard of those going bad unless they were abused by PO) b) buy a used differential that was also bad, and c) send it back, only to be sent another bad unit. gah... seriously.

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1985 300D Turbo "Eunis"

I doubt you would have 3 bad diffs in a row. My vote is for the carrier (center) bearing and/or u-joint.

i would be really surprised if the u-joint were able to produce this noise, but the carrier bearing has been discussed as a possible culprit (my friend referred to it as "the driveshaft bearing"... i'm pretty sure you're talking about the same part). how difficult is it to change that?

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1985 300D Turbo "Eunis"

Quote:
Originally Posted by Brian Carlton
The determination of "differential" or "wheel bearing" can be assisted if the following question can be answered:

Does the noise almost go away entirely when the drive shaft is unloaded?

The drive shaft is unloaded when you are cruising along at a steady speed and you lift your right foot ever so slightly so that the vehicle just begins to slow down. If you lift too far, the shaft will load up in the opposite direction and the noise may return.

Please attempt to reduce or eliminate the noise via your right foot, in the manner described, and report back.

When traveling at a steady rate any where from 40-65mph I get a high pitched noise. When I let off the fuel pedal the sound goes away and depress again and it returns. Is this bad wheel bearing? have something to do with drive shaft, differential?? Differential fluid has been changed, rear axles are new, rear brakes are new.

A whining noise from the rear of my car is almost always the wife. Sometimes the whining noise seems to come from the other front seat also......

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Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

Levi - letting your foot off to unload the differential and having the noise go away points directly to the differential - wheel bearings would continue regardless of accelleration.

John

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John Hughes, was in Landstuhl, Germany but currently in San Antonio, TX


1978 280CE Astral Silver now 59,xxx miles and counting "Silber-Kugel"
1986 300E Black Pearl Metallic 143,xxx miles 5-spd daily driver w/ blk leather "Schwarz-Schönheit"
1989 190E 2.6 (euro) 5-spd Desert Taupe 112,xxx kms Had to leave behind in Germany!!! "Helga"
1983 300D Pastel Beige now 312,xxx + miles SOLD

OBK#24

I did it on the driveway with ramps without any great difficulty. Factory Shop Manual helps.

John

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John Hughes, was in Landstuhl, Germany but currently in San Antonio, TX


1978 280CE Astral Silver now 59,xxx miles and counting "Silber-Kugel"
1986 300E Black Pearl Metallic 143,xxx miles 5-spd daily driver w/ blk leather "Schwarz-Schönheit"
1989 190E 2.6 (euro) 5-spd Desert Taupe 112,xxx kms Had to leave behind in Germany!!! "Helga"
1983 300D Pastel Beige now 312,xxx + miles SOLD

OBK#24

had the same problem with my car, they way we fiquired out it was bearing me and dealer tech at mb took out on deserted rd at good speed and made sharp left and rifht turns if noise goes away its bearing , if it goes away on sharp left it left side bearing right turn goes away right bearing hope this helps

I saw this post and I think it might pertain to my car. I have an 1982 380SL
with an honest 52k miles on it. It makes a whirring noise that starts around
60-65 mph a gets a bit louder as the speed increases. If I lift on the gas
pedal the noise will go away until the car slows down and comes back when I
think the drive shaft is getting loaded? I have checked the wheel bearings
and the diff level is correct. Any Ideas?

Thanks Steve Dabney

I have noticed a high pitched sound like a hair dryer in the trunk in the 85 SD lately. I believe it may be a wheel bearing on the left side, seems louder on the drivers side when I listen with the windows down.

I'm wondering if the bearing noise will go away when I check it unloaded, lifted off the ground???

It could also be the driveshaft carrier bearing. But I would start off by changing out the diff fluid with synthetic or use staight 90w or higher to see if it will go away. If not then you need find a way to get down there and hear where the noise is located.


It might go away but be sure to properly support the vehicle if you're going to attempt it.

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1983 123.133 California
- GreaseCar Veg System

I am interested in this as well and have posted previously on the subject. My 85 300SD continues to make a loud noise that seems to be coming from the passenger side rear. Have changed the diff oil too. I have had the vehicle on jackstands and running and cannot duplicate the noise. The noise is present regardless of pressing on the pedal or coasting. I also seem to have some driveline noise around the center of the car but thats a different subject. Also something of note, when the car was on jackstands, speedo aproaching 30mph, the rpms and speed increase dramatically. Is that the turbo kicking in?

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1985 Mercedes Benz 300SD, TMU
2015 Chrysler 200S

This seems like a very common problem with these cars. I've had the same problem with whine since I bought mine. I've changed to synthetic gear lube and I've checked the wheel bearings, etc. It seems to be coming from the diff and maybe since the subframe mounts are old, the noise is being transmitted more effectively to the cabin.

I still need to have a look-see at the ring and pinion gears one of these days to see how much wear is on them and check the preload on the bearings.

Has anyone priced a new ring gear and pinion gear (that is, if they're still available) from the dealer parts department?

Curt

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NoSnooz
Grand Rapids MI

84 190D 2.2 Auto 228,000