My 5... well, 5 sparkplug rotary RX-7 engine was smooth as silk.

Several factory. Odd number of cylinders, its a diesel, and a not very robust engine mounting system. After wrenching on these for some time, I really think the engine mounts are a joke. Go look at a Dodge Cummins powered truck, they have some stout mounts. I have NEVER had to replace one or even see one go bad.

__________________
1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

The nature of the mounts dictates the problem. If you need a soft mount that isolates the engine from the frame, by definition it's going to take a beating. It's not easy to engineer a "robust" mounting system that is simultaneously "soft".

I'm not familiar with the Cummins, but, you can rigidly bolt a 6 cylinder engine to the frame and not feel much vibration from it.

At Idle, with the stereo on you cant tell mine apart from a well tuned gasoline engine. It is perfectly still and idles softly. As a matter of fact, many people are shocked to learn that it is a diesel. Mine is a 6 cylinder though and has pretty good power. It will GET UP AND GO when I want it to and then you'll hear it. I hate to sell it because it is so perfect and one rarely gets lucky to find a car and the engine in such pristine condition but I would really like to have a 1999 S500.

The Cummins is not a rigid mount, but the mounting system is a very heavy duty unit, but does have a rubber isolator just like the mercedes. I think the way the load is spread out from the engine side on the Mercedes is not adequate. The rubber could be just as pliable but maybe a different compound.

__________________
1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

I agree with you there. The load is very concentrated on a narrow portion of the rubber and the longevity is not present. But, the mounts are not costly and, usually, are not that difficult to change........especially with a lift.

Brian,

How the heck do you reply so fast?!
Does your computer "ding" when someone makes a post?

Yes the mounts are cheap, but I like the idea of never having to change them or mayby only once in the cars life. I remember that when I sold my '73 Camaro it still had the original mounts. I like that.

__________________
1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

wankel. I built a cool model of one in ~1975?

__________________
Rob M
Norwich, VT USA
1980 240D Euro delivery 4 speed manual silver/blue
~160K miles