Odd vibrating droning sound at 1800 - 2000 rpm

[janke.lochner]

Hi guys

I took my 1995 C220 manual for a full service about 2 months ago, and the mechanic told me that my engine mountings must be replaced. I then bought the mountings myself and had it installed 2 weeks ago. After this installation, I experienced an odd droning sound under the hood in each gear between 1800 and 2000 rpm. I do not hear it when my car is in idle.

Also, my gear shifter was quite stiff after the engine mount replacement and I had to push the clutch pedal down hard onto the floor for a decent gear change. I then decided to purchace a transmission mount and install it myself. I did this yesterday. The gear shifter as well as the clutch pedal are like new again, but the droning sound persists. :confused:

Any ideas as to why there is a droning sound and where it's coming from? I did not hear it with the older mountings, but the loud engine and the vibrations throughout the car was so bad, I might not have noticed it. Will I be able to solve this problem myself, or would I have to take it in to be taken care of?

Any replies would be much appreciated :)

[RemoLexi]

I have seen before engine mounts that behaved as such, make sure the engine mounts you purchased are not made it china!

[janke.lochner]

Well, it isnt genuine Merc parts... but its also not Chinese rip offs. It was OEM quality parts. It must have something to do with the gearbox or something, because it will only make the sound in any gear at the above mentioned rpm's. In idle it's quiet.

[RemoLexi]

Any chance the rubber mount for the driveline center support has torn from doing the trans mount ?

[janke.lochner]

I will check next week. I quickly checked it out when I replaced the tranny mount and nothing seemed to be out of place - I will give it a thorough check when I have access to a garage and equipment again next weekend. Will keep you upto date with what I find. Thanks for the suggestions :).

[janke.lochner]

Oh, I forgot to add that the noise only happens at the above mentioned revs and dissipates completely on/above 2000 rpm

[janke.lochner]

I checked under my car and the centre support seemed to be still in place. I also had to tighten the top bolts on both my engine mounts as the little grease monkey who did the job for me left it quite loose for some reason. Fixing this problem did not seem to have an effect on the droning sound.

I let someone who has been working with Mercs for a long time listen to it, and he told me that it was the rear silencer in my exhaust system that was faulty (might be the front one too). So I am going to just leave it for now and take care of it at a later stage. At least I can not hear the noise when my radio is on.