tbilisi79

This one got me puzzled.
2008 4 matic. 103 k miles.
New engine mounts, tranny mount, spark plugs. Most of the vibrations are gone, but I can still feel a harmonic vibration at idle between 1500-2000. Its very faint but its there.

Engine number checked out before I bought the car and is well past the questionable earlier engines.

Could it be the balancer?

Thank You.

konigstiger

Already addressed mounts, here are relevant bulletins.

tbilisi79

Thank you. I sure hope its not the transfer case.

Senecat

Pull codes.

tbilisi79

For miss fire? Wouldnt the check engine light up?

tbilisi79

After doing some more research, I think the next step is to clean the TB and hope the buzzing at idle in gear will go away. If not, asking a shop with STAR to raise rpm by 50 like some people mentioned.

As for on the slight road vibration in steering wheel, is it possible for the flex disk (guibo) to be worn out or lose? I get no noises and its smooth all the way to 90 MPH. I am thinking the engine vibration that I get at 1500 rpm is the main issue here. Someone mentioned an alternator ground strap TSB. Dont see how that can cause vibrations but its cheap enough to try and I will order it later this week.
Again, new MB engine and tranny mounts.

I swear to me it feels like the tranny mount gone bad symptom, but I had it changed with an MB unit already. Unless it was damaged during motor mount install. I have to get under the car.

Thank you again.

Minh

Likely the vibration cause by propeller and centric bearing (the rubber of centric bearing is impact by weight of propeller shaft and is not able to keep propeller shaft in central, see detail on the photo enclosed ) cause the vibration when car at 60-70mph

tbilisi79

Thank you.
What part is that and where is it located? Whats the full name of it?

Do you mean drive shaft center bearing?

Minh

Yes, i mean driver shafts center bearing

tbilisi79

Any way to check that the part is bad? I do get a small howling noise above 30 mph that goes away once I slow down to 20 mph.

kevm14

You'd probably grab the shaft and check for radial play.

tbilisi79

Got it. Thank you!

JohnLane

I'm dealing with bad vibrations in my 221 S-65. Misfire solved with fresh spark plugs.... She makes all the YANK she should.... But 1500-2500 there is a pronounced vibration at engine speed. Under load and deceleration. Vibration happens during decel fuel cut so seems it can't be how she is running.. Happens regardless of what ratio the box is in. Zero codes. Mounts are all fresh. I recall years ago hearing of a torque converter being able to do this...

Thoughts?

Senecat

Yup. Replace them all.

tbilisi79

Gonna take the car to MB shop. Check with star for codes, hoping maybe one of the coils is weak thats causing my 1500 rpm vibration at idle.
Also raise it by 50 rpm to cure the buzz at times in drive when stopped.