W115 Metal Squeek from rear end - PeachParts Mercedes-Benz Forum

Techy-Mechy · #1 10-02-2014, 11:30 PM

I am trying to get my dads old 1974 240D (W115 chassis) - 4 speed manual running right. I have a metal on metal sounding squeak that has me baffled. I am hoping that someone may be able to help me.

The metal on metal squeak occurs when I am engine braking (continuously), upshifting (briefly, occurs when the engine rpm is increasing due to engine braking) or running in reverse (when I'm really accelerating in reverse). It seems to be worse when I am engine braking on hills. The sound seems to be coming from the rear end of the car or in the carrier bearing/UJ area (it's really hard to tell on the 240D diesel) The sound goes away if I push in the clutch.

The universal joint is tight. I don't know what the carrier bearing should feel like.

I sprayed some silicon lubricant around the carrier bearing and universal joint and the noise went away.

Now the noise has returned and I sprayed some more lubricant around the carrier bearing. The noise did not go away this time.

My axles have surface rust near the differential. I sprayed the lubricant around there and it seemed to quieten the metal on metal sound down some, but did not eliminate it.

I have replaced the flex disks about 3 years ago and they still look great.
I can move my drive shaft by hand. But, the carrier bearing rubber bearing holder seems to be in good shape (but it's really hard to see it well).

Does anyone have any idea of what can be causing the metal on metal sound when I engine brake on hills, run in reverse, or briefly when I upshift? I am a little concerned that it could be the carrier bearing or the UJ is super sensitive.

I could sure use some advice.

Thanks,

Dave

Techy-Mechy · #2 10-04-2014, 06:10 PM

Here are some pics of my UJ, carrier bearing, flex disks and differential/drive axel. I have a mp3 of the sound that I'd like to post or send to people if they think it would help.

Thanks for the advice.

Techy-Mechy · #3 10-04-2014, 07:33 PM

I can't get a wav file small enough to be loaded on the web site.

Please contact me and I'll email the recording.

Thanks,

Dave

D&W · #4 10-05-2014, 12:12 AM

I had pretty crazy metal noises in the rear of my w108... it was worn forward trailing arm bushings. not sure if that is something worth looking at in your case but it can't hurt i guess

Techy-Mechy · #5 10-05-2014, 02:50 AM

Hi D&W,

Thanks for the hint. I'll look at this tomorrow.

Dave

Stretch · #6 10-05-2014, 04:43 AM

I'd start with the propshaft bearing seeing as you had a positive response from the silicone spraying - the problem with silicone lubricant is that whilst it seems to provide a solution on the first spray it seems to me to cause longer term drying out problems. This is most certainly the case for door locks. I don't like silicone lubricants for this reason and they've been banned from my garage!