Noise 1980 240D help ID - PeachParts Mercedes-Benz Forum

Treeman · #1 12-26-2013, 01:32 AM

I have a new noise that only happens when I am moving and starts at about 10mph in any gear.

I have searched the forum for descriptions of Noises others have heard or hear.
This is not a grind, whistle or growl or thump or squeal.

It sounds like what you hear when you blow over the top of a large bottle and it's loud and gets louder the faster you go, until it peaks at about 30mph.
Does it with clutch engaged or disengaged.
Depressing brakes does not alter the noise, turning the steering wheel changes nothing.

It sounds like the noise is coming from under the gearshift of the manual transmission.
But I'm starting to think it may be coming more to the passenger side front wheel or somewhere in between.

I am kinda scared to keep driving the car to try to pinpoint the noise in fear I will tear something up.
My wrenching bud seems to think that somehow we have reverse and forward gears partially engaged at the same time.
But it seems to me this would be close to impossible because the gears are tight, either engaged or not ie there is no slop there.

Hope the noise description helps.
If it will help I will record the noise and post it.
You will have no problem hearing what I have tried to describe.

Appreciate the help in advance.

Stretch · #2 12-26-2013, 02:14 AM

Well if you think it is drive train related - have you checked oil / fluid levels?

Treeman · #3 12-26-2013, 03:19 PM

Quote:

Originally Posted by Stretch

Well if you think it is drive train related - have you checked oil / fluid levels?

All checked and good.

Quote:

Originally Posted by Left Coast

Is the speedo jumping around when this is happening?

No

Treeman · #4 12-26-2013, 05:07 PM

Just jacked car up and and ran through the gears and got the noise, waiting for additional person so I can get under car to find the source of the sound. Is there a test to determine if this is the Throwout or Carrier bearing once I am under car? I will check the Center Support. Check back soon.

BWhitmore · #5 12-26-2013, 09:05 PM

If when depressing the clutch pedal ( engine running) the sound changes volume or tone it is most likely the throw out bearing.

Treeman · #6 12-26-2013, 09:27 PM

Quote:

Originally Posted by BWhitmore

If when depressing the clutch pedal ( engine running) the sound changes volume or tone it is most likely the throw out bearing.

Great, that test rules out the TOB. Sound does not change when engaging or disengagement of clutch.

Sound varies only with speed only.

Aquaticedge · #7 12-26-2013, 02:27 AM

Sounds like a bearing is going out, possibly Throwout or Carrier?

vstech · #8 12-26-2013, 10:58 AM

... I'd think it's the air filter being off... or a leak in the intake somewhere.
but it could easily be a bad throwout bearing, or input shaft bearing.

ROLLGUY · #9 12-26-2013, 11:33 AM

My vote is for the center support bearing. I was working on a VW Toureag, and it had a similar noise. I put it on a lift with someone driving it with me underneath. I was able to pinpoint the noise and found it to be the center support bearing......Rich

Left Coast · #10 12-26-2013, 11:47 AM

Is the speedo jumping around when this is happening?

BWhitmore · #11 12-26-2013, 09:10 PM

The best listening device is a mechanic's stethoscope or if you don't have one a wooden stick works pretty well also. Just place one end of the stick on the bell housing or the carrier bearing and the other end up against your ear. You will be able to hear the growling noise.

Treeman · #12 12-26-2013, 09:33 PM

Quote:

Originally Posted by BWhitmore

The best listening device is a mechanic's stethoscope or if you don't have one a wooden stick works pretty well also. Just place one end of the stick on the bell housing or the carrier bearing and the other end up against your ear. You will be able to hear the growling noise.

No stethoscope but I do have allot of wooden sticks. I was kinda scared to crawl up under the car while going through the gears. This will surely be the way I will investigate noises from here on out.
Thanks

BWhitmore · #13 12-26-2013, 09:53 PM

PLEASE make sure the car is securely positioned on jack stands before getting underneath the car - running or not.

BWhitmore · #14 12-26-2013, 09:54 PM

You will probably need to crawl under the car but PLEASE make sure the car is securely positioned on jack stands before getting underneath the car - running or not.

BenCohen-300TD · #15 12-27-2013, 03:34 PM

I'm having exactly the same sound and problem - it just cropped up this weekend on a long drive. Sounds like an owl is trapped behind the dash or in a wheel well, and I can feel the slight vibration in the accelerator pedal. It happens when I hit 45mph, and was intermittent at first and now happens every time I hit 45.

I have it at the shop down the street to see if they can diagnose it. My money is on a wheel bearing. It sounds like from this forum the same sound could happen with the speedometer cable, but my speedo isn't acting weird.

I'll post what they come back with.