Don't waste your time on the anti-vibration t-mount. It's pretty floppy when new. I replace the one on my 240 and it didn't do anything for the shaky idle I once had. Could your idle rpm be slightly low. That would cause shaky idle.

Do 240Ds have rack dampener pin?

On my 300D I had a terrible idle shake and replaced both of my motor mounts. It helped, but not as much as I wanted.

I read around and ended up buying a new rack pin. It's the gold updated one.

I was in and out in 15 minutes. That did the trick. No more floppy idle.

No, it's a turbo thing.

That's right, no damper pin on this model.

Already have the idle turned up pretty high to minimize the vibration. The problem is that if you turn it too high the car wants to move forward with no foot on the accelerator, and I have to actually apply some good brake to hold her back when idling in gear at a stop light, so probably need to actually lower the idle a bit and tolerate a little more of that vibration.

my 240D shakes the same way. No AC on, in neutral, it is very smooth with the idle adjustment just barely above minimum point. In drive, and especially in drive with AC on, I need to turn the idle up to get it to not be a bad vibration.

It is better when warm, but still not great.

Ive heard all the causes, and Ive heard that the 240d will idle like a tractor. Not sure what is right though. Never heard to check the exhaust mounts, and while I think mine are fine, it is plausible as it is a 10ft mass hanging off the engine.

It is interesting to me because it seems to be a common problem, and yet many of us are struggling to figure it out. I really hate to just accept it because there is no way this car did this when it was new or MB would have never sold a single 240D. And you are right, in gear and/or with the AC on, things get even worse. When I first bought the car, thought it would be a simple matter of motor mounts, but that did almost nothing to remedy the problem.

I thought mine was due to having a few busted screws on the pulley that attaches to the harmonic balancer - causing no balance... but after my pulley came off and I replaced it, still the same issue...

I will say that my car is like new, everything is maintained, but I have not physically replaced the motor mounts as they do not appear badly compressed. But perhaps the right mount would cause some help...

New motor mounts has been successful cure for many, so you might try that, as they are not too expensive. But it didn't help me - the mounts I removed were in good shape.

... and per my and my indy's looks, mine are too...

It is worth a shot when I have time. Did you use OE mounts? There are stories of counterfeit and foreign mounts failing in no time flat.

They were the OEM ones.

i once had a 300SD that was vibrating in park and reverse, it turned out to be a broken motor shock on one side...the shock failed and the damper rod travel/bottomed out way to soon...we replaced the broken shock and all was well again.

My '77 240D is the same. I did a compression test which came back showing all of the cylinders being in pretty good shape (above 300) but the first cylinder was at about 310 while the 3 others were all at about 370-380. I think that is a wide enough range between the first cylinder and the others to account for rough idle.

Any Luck
 

Just wondering if you found A solution to this problem. I have the same problem on my 81 240 D and have tried all the things you have with no luck. Thanks

Nope, still rattling/vibration at idle. Want to check exhaust mounts next, and eventually I need to do the compression check. That is the one I least want to do, because it tells me the engine has some issues, and there will not be an easy fix. But if I want to know the truth...I need to do it.

I, too, am afflicted with this ailment... Did you find a cure???