what is growling/rattling/spinning behind my 300TD dashboard? - Page 2 - PeachParts Mercedes-Benz Forum

240dddd · #16 09-17-2020, 03:13 PM

Quote:

Originally Posted by t walgamuth

I was going to suggest might be fan clutch.

Coincidentally I replaced my fan clutch a week prior to changing the motor mounts and it didn't have any effect on the noise.

If it wasn't clear from my last post, this problem is solved and I'm fairly certain that the old mounts were the source of the rattling sound.

What I mean is that I can take old mounts and shake them by hand and hear something moving and rattling around inside the mount, as if something internal to the mounts broke and is bouncing around inside the mount.

t walgamuth · #17 09-21-2020, 10:09 PM

Glad you figured it out!

t walgamuth · #18 04-02-2021, 11:24 AM

Quote:

Originally Posted by ykobayashi

Ill toss in my diagnosis. I don’t think it’s a speedo cable...aren’t the 124s electronic? I guess they have a motor in there.

Anyhow I have had buzzing and whirring from my CCU in three of my mb diesels. It was caused by relays opening and closing at an audible frequency so it made kind of a tone so to speak like a fly flapping its wings. I just fixed this this month in my SD by pulling the CCU and resoldering it’s bad solder joints. On visual inspection there were at least five cracked solder joints (ring around the solder bump from 38 years of thermal cycling). Free fix. This has worked in my cars.

Somehow the shutting down and listening to it slowly go away blasts my theory.

Could it be a defective water temperature valve? Like a squeaky faucet? Doesn’t the 124 have a more sophisticated monovalve than the 123? That may explain the bleed down of the noise. It can also be something jammed in the blower?

Good luck chasing it down.

So is the speedo cable mechanical or electrical in the 124 car?