Very slight cold idle steering wheel vibration - PeachParts Mercedes-Benz Forum

JHZR2 · #1 10-19-2018, 10:21 AM

1991 W126 350SD.

Starts beautifully and strong. No issues or challenges. Short glow, barely crank, idles great.

But when cold, there is ever so slight a vibration in the steering wheel. Just enough to observe a little movement in the cruise control stalk.

Ive never noticed this with any of my w123 cars, even my 240D, which has a pretty strong idle shake when in D and AC on.

This shake in the w126 is so minor that just having a hand on the wheel dampens it. But it is non-existent when the engine is warm, so there is something going on.

What confuses me with this, and why I’m asking, is because I don’t observe anything in my w123 cars, as noted. The 240D seemingly to me has the same type steering system as my 350sd, and it shakes enough at idle (smooth as silk under load) to vibrate thehood). But the steering wheel is rock solid.

Perhaps it’s due to the adjustable column on the w126? Or could it be some mounts or bolts? Perhaps something that once warm, behaves differently?

Thanks!

DieselPaul · #2 10-19-2018, 10:43 AM

I would check the bolts that hold the column up the to cross support in the dash. I've not gotten them tight enough before and had all kinds of annoying rattles. The other thing too is I can't remember what it looks like on a 126 but the steering coupler wearing out would let things move, but that would manifest itself in play all of the time.

I anxiously await someone telling you the car shakes because you have bent rods.

Diseasel300 · #3 10-19-2018, 11:22 AM

Resonance. When cold, the idle speed is different, and even though it feels smooth to you as a driver, it's rougher. Find that "happy place" with something that has a similar resonant frequency, and you get vibration. Check your motor mounts.

Squiggle Dog · #4 10-19-2018, 01:06 PM

Ugh. This JUST started happening on my roommate's 1991 W126 350SDL after I replaced the combination switch, but all I did was remove the steering wheel and the plastic on the steering column. When those parts went back on, they went back on the way they came off.

But when the engine is idling, the steering wheel vibrates and makes a buzzing noise if it's not being held. I'm sure the engine mounts are shot, etc., but it's odd that it started happening right after I replaced the combination switch.

I did also clean the old grease off of the steering column and put new grease on it, as well as slightly loosened the play in the steering box because it's difficult to turn the steering wheel at low speeds, even after rebuilding the power steering pump. Did you do any of these things right before the sound started happening?

Junkman · #5 10-19-2018, 07:19 PM

The buzz may be plastic column cladding vibrations. I have this on my falling apart Dodge.

JHZR2 · #6 10-19-2018, 08:57 PM

Quote:

Originally Posted by DieselPaul

I would check the bolts that hold the column up the to cross support in the dash. I've not gotten them tight enough before and had all kinds of annoying rattles. The other thing too is I can't remember what it looks like on a 126 but the steering coupler wearing out would let things move, but that would manifest itself in play all of the time.

I anxiously await someone telling you the car shakes because you have bent rods.

Bent rods wouldn’t vibrate stopped at idle.

This vibration is only when stopped.