HELP! Cant figure this out.
 

I have recently purchased a 98 E320 and this is my first MB so I might be wrong is asking this question.

I have been a passenger aboard many MB's and have always found them to be very smooth,but I seem to have a symptom that that I can only discribe as a " harmonic vibration". At just about any speed above 45, as long as the engine remains in a constant state of power I get what feels like a pulsing type feeling throughout the car and what sounds variable in pitch.

I want to say that I have been through this car and it was a CPO by the previous owner and now myself (3rd owner) I have no pulling left or right,no brake pulsation, nitrogeon filled tires at less than 3000 miles old,and NO vibration in the steering system at all.

Car has 150k and honestly in perfect condition,other than the radio issue (volume) and this, so I would like to figure out what this is and if I can fix it.

It is not particularly loud or noticable but I can feel it .

Thanks for any input.

Flex disks, trans and/or motor mounts perhaps. Could also be tires, balance or worn suspension bushings.

Ok well let me say that I have rotated and balanced the tires and one thing I do know is there is no transferrence of vibration through the steering system.

It feels and I think that it is eithier in the driveline or in the engine( harmonic balancer??)

1998 was the first year for M112's (I think), so it certainly could be the harmonic balancer.

Has yours been replaced? I believe it was done under recall, your MB dealer should have it in the VMI if it was.

If it is definitely engine related, after verifying the harmonic balancer, I would suspect engine or transmission mounts.

Of course the engine harmonic balancer was recalled on that and most 1998-2000 V-6 engines.

However it seems that many early replacement balancers are now failing as well.

IF you switch OFF the engine & coast...does the vibration go away?

Yeah, I guess what you want to know is whether the vibration is engine RPM dependent, or wheel speed dependent. Above is a good way to check...... You might also be able to do it by popping into neutral, which will leave you with power brake and steering......

Just a thought..might want to check the wheel bearings in the front..Also, (happen to me once) check the lug nuts... they may have backed loose a bit especially if you have any tire or brake service..But listen to MB DOC and the others..you need to isolate when it is occurring...is only at certain speed.. will it do it in neutral..will it do it with only passenger in there..etc.. Start with the simple first then work your way up to the big stuff...I wish you the best of luck and hope its a cheap fix....

I dont know if it goes away If the engine is off but I will try that tomorrow.

BTW: Does anyone have acess to VMI??
If I get the VIN to someone Could you look it up for me????

I just bought this Car And really love it but Right now trips to dealer are out of the question.

TP.

Ok It seems that It is not engine dependant because when driving at about 80 mph I put the car in nuetral and no change in pitch or intensity and the engine was at idle.

Ideas where to start??

It seems that it is speed dependant.

Things that move in N. Wheel bearings, tire balance and alignment, and suspension; axles, differential and prob drive shaft.

I'm absolutely certain DOC can think of other things I forgot to mention the 2nd time too......

Don't you have a center bearing support for the drive shaft?

Crash one,

I dont know if it does or not. I just got this car and being a girl I dont have acess to a lift or jack.

So it sounds like I need to take it to a shop.
I just dont want to be taken, if it is something that I can narrow down so I have an idea if I am being BS'd . if you now what I mean.

Tm,

Thanks I will keep trying I guess Any other tests or Ideas to help narrow it down??

You say you can feel it, that means vib of some sort to me?

Do you feel it in the seat, at the steering wheel, in the shifter, where?