Vintage Cars: W123 Low Revs Rumble, vibration noise, rapid reply

Question
QUESTION: Hello Ron,

I have a 1981 300D manual with a low rumble, though no noticeable vibration at around  900/1200pm.

If I depress the clutch or drop a gear, the noise goes instantly, if I accelerate out it disappears more slowly as the rev’s rise.

Is it just one of the car idiosyncrasies or is it telling me something?

Actually, I’m not sure if it’s either wearing off, or I’m getting used to it.

The car has been stood for two years, and not done more than 10k leading up to that.

Any help would be very much appreciated!!

Thanks in advance.

Best wishes,

Paul





ANSWER: well you did not mention miles, but could be a lot of things, if its a shudder - clutch, vibration - throw out bearing, knock - engine mounts, could be mounting of exhaust system (uses rubber rings)
All of which are no big deal - they will get worse then you can fix it!

---------- FOLLOW-UP ----------

QUESTION: Hi Ron,

Thanks so much for your rapid reply.

I didn't mention miles because I don't believe the clock. It says 120k Kms, that saidhowever, the engine makes no smoke, purrs, and pulls well, so maybe 220k kms - 135K miles, something like.
Anyway, there is no vibration at all - that I can notice at any rate.
Could it be because it has stood so long?
Cheers,
Paul

ANSWER: no smoke , purrs well, and pulls, I would not worry about it. I suspect it is some sort of vibration noise.  DO check the rubber mounts for the exhaust and check the motor mounts and the air cleaner mounts - whic are all  rubber - all can cause all sorts of noise at low RPM when the engine is at "least harmony"  
Sitting is never good for these ol gals exercise her well ....

---------- FOLLOW-UP ----------

QUESTION: Thanks again Ron,

Just one mare basic question, please.
When I depress the clutch, does my drivetrain still turn?

Cheers,

Puul

Answer
if you mean does the drive shaft still turn and engage the wheels , no
In a car, you need a clutch because the engine spins all the time, but the car's wheels do not. In order for­ a car to stop without killing the engine, the wheels need to be disconnected from the engine . The clutch allows this by controlling the slippage between them.
Worn clutches will cause more drag, and will feel like the car still wants to go