Suspension noise experts please weigh in!

[psaboic]

Hi folks,

Posted this earlier but ended up doing some serious rust repair under the battery tray first.

The issue is I am getting a random clunk or pop sound from the passenger side whenever the car goes over a small dip or bump that unloads the suspension. It sounds like it is coming from about 6-12" rearward of where the door and fender meet.

So far I have checked all suspension parts for issues. All bolts are tight, Sway bar bushing is new, shock is not loose or broken, guide rod bushing looks good, no play in the ball joint or bearing, bouncing the car at the fender does not produce the sound, nor does rocking the wheel. When driving, doing some serious low speed swerving back and forth does not produce the sound. I even opened the door and jiggled the hell out of it in case something was loose in the door....no joy. Door hinges are lubed and not broken.

Car steers, turns, and stops about as well as a 41 year old car with 386,000 miles should.

Any ideas??

[psaboic]

Anybody????

[Sugar Bear]

Look closely at the base of the A pillar for cracks.

Examine the sway bar mounting for corrosion under the battery box.

Lubricate the door hinges through the grease port in the center.

Rear subframe bushings in good shape? If the rear of the car wanders on the highway they are bad.

[Graham]

Presume this is the '83 300D. I had similar clunking on my '85. We replaced the guide rod mounts and LCA bushings. We took the springs out because my local shop said one was broken (It wasn't!). Put in new springs anyway. No noise after doing this. The guide rod mounts and LCA bushings may seem OK, but no way to really know until you take things apart.

Front end noise on my R107 turned out to subframe mount bolts that needed re- torqueing. However, this showed up mainly when making slow turns.

[Alec300SD]

Agreed X2.
The rubber bushing in Item 26 (guide rod mount) has probably perished.

https://nemigaparts.com/cat_spares/epc/mercedes/1/fg/123130/68k/33/060/

[psaboic]

The guide rod bushing is what I'm afraid of. Had to just finish repairing the sway bar bushing mount and area under the battery..... quite a bit of corrosion. I'll check the A pillar and door hinges too. I heard you can remove the guide rod mount without removing the spring by using a come-along to move the control arm. Not sure I like that idea but finding the proper spring compressor might be tough ....

[Graham]

Originally Posted by psaboic

Not sure I like that idea but finding the proper spring compressor might be tough ....

We, (or more accurately, my friend who has multiple 123s), bought a spring compressor. It cost less than $100 even here in Canada. You may even be able to borrow one or get a used one.

The opening in the engine bay had been opened up on my car, but doing that should not be a show stopper. It's possible some compressors may now be of a size that doesn't need that? I am sure you would get many comments here if you asked about spring compressors. Better than that tree option

[Alec300SD]

No need for a spring compressor.
I've just used the OEM Bilstein jack wedged in horizontally into the wheel well to slowly move the lower control arm forward.

It can't be too high up in the wheel well otherwise you can't turn the crank.
I placed a piece of wood between the jack and wheel well to protect the undercoating.

[Diesel911]

I bought one of these and while it works, I have not used it to troubleshoot anything so far. See the attached picture.

6-Channel Chassis ears Automotive Electronic Stethoscope Noise Finder Tool Set Drop Shipping also known as a chassis ear.

The sound or a signal comes up the wire into the control module. Your either watch the light bars or use a headphone to see which has the loudest sound to identify where the sound is coming from.

Mine has headphones and I have only tested it. It seems to work, and you will likely need it later.

They are reasonably priced on AliExpress or Temu.com. I bought mine from one of those.

You can go to Amazon and seem ones that visibly look the same and you can look at the customer ratings.

In my case my car thumped when stopping and it turned out to be the guide rail mounts. However, where sound comes from is deceptive.

It could be the transmission mount thumping or the idler arm of the steering which is on the passenger side.

[psaboic]

Interesting. I might have to look into getting one of those. I could see where they would really come in handy....