Mystery rattling noise

[dante53]

Hi, my name is Dante. I'm a new member from Italy. Already did my presentation in general area. I'm trying to diagnose a mistery noise on my 65 230 SL. Anytime I accelerate starting from a stop, I hear a rattling noise whose frequency is tuned with engine RPM. It happens only with forward gear engaged (not in reverse and not while revving in neutral) and it is louder with cold engine. It stops (or gets inaudible) at cruising speed or decelerating. I am quite sure it does not come from the engine as it seems to come from the transmission tunnel. My personal idea is that it may come from the speedo cable even though my mec suggested replacement of the 90 mm joint disc (already ordered). Did anybody have the same problem?

[merrill]

have you checked the exhaust system - resonator / muffler for a leak or seam failure?
it is possible that while accelerating there is more exhaust pressure and causing noise.

[J. Huber]

Hi Dante,

I chased a similar sound for a long time, fearing the worst. In my case it turned out a simple fix. Have a look at this thread and see if it helps...

http://www.sl113.org/forums/index.php?topic=11557.0

PS My last post in that thread gets to the remedy....

[dante53]

Next week my mechanic will replace the entire  exhaust system and the joint disc. A few minutes ago I checked the speedo cable and found it was very loose and interfering with the accelerator spring. I set it aside to avoid any intererence with the accelerator. So by the end of the week, whichever is the cause, it should be fixed. At least I hope so. I will report as soon as the job is done. The noise is quite like that of the sewing machine or an automatic gun: taca-taca-taca-taca ........

[Rodolfo]

Hi Dante,

is the rattle noise fixed?
I had one rattle which was solved with a simple fix: the throtle mechanism (linkage) going from gaspedal and so further on was rattling against the motor (near outlet collector). By adjusting some screws it was fixed.


best regards, Rudy

[dante53]

Hi Rodolfo. The noise isn't fixed. You can hear it only when starting from a stop. It's frequency goes in accordance with acceleration and then stops as soon as you release the accelerator pedal or get to your cruising speed. My mech is changing the transmission joint disc. He will also check if the nut that keeps in  its place the helicoidal speedo transmission gear has loosen.

[W113SL]

Dante:  Did you check to see if the metal heat shield that protects the right front underside from exhaust heat has loosened over time.  I have found that it, if loose can, cause the rattle you are referring to.

Good luck,

Pete Lesler
W113SL

[dante53]

Pete my mech will check that too as he will replace the entire exhaust system. Thank you for the hint