How smooth and quiet can a W124 diesel be made?
 

I'm 6 weeks into this car, my first diesel. I looked at a few before buying this one. This is a '91 300d with just 90k on it. It drove fairly well, the price was fair, so I bought it. Like any car, you notice things over the course of weeks that you didn't notice on the test drive. One thing that has started to bug me, is the low rumble when accelerating. Once you're up to 40 mph or so, you don't hear it anymore. But in start and stop traffic, it gets annoying with the roar/rumble of the diesel engine.

At idle, there is a gentle shake of the car, not much. I know a diesel of this vintage can't be compared to a gas, but my gas stick shift 1988 Toyota Camry, you can hardly tell it's running at idle. I'd previously drove a '92 300d that maybe I should have bought, that was super quiet; I didn't pay attention to any idle shake at the time.

So I wonder, how quiet and vibration free can a W124 2.5 diesel be made? Someone said the valves on this one are self adjusting, so there's nothing there for me to do. I'm assuming I'll have to take it into a mechanic to do any finer tuning to it.
1991 300d, 90k

Mine shakes like hell too at idle, I'm going to do a valve adjustment this weekend which I hope will fix the problem.

You're right, it will never be as smooth as a gasser but you can get close (at least on the later cars). Check to see if your engine mounts are in good shape. On the 124s they are fluid filled and can harden and/or crack and leak. Often times the mount may look good but when you take it out it's obvious it's bad. At 90,000 miles if you still have the original mounts I'd probably replace them just to make sure. If you install them yourself it's not very expensive.

IMHO the noise and vibration we get from our diesels isn't annoying, it's endearing.

This is virtually impossible to provide comparative info for over the internet. One person's "slight roughness" is another person's "dead smooth". It all depends on perspective.

If you are using a FI gasser as a basis, no diesel will ever come close........especially five cylinders due to the inherent unbalance.

See if you can check out other 2.5's..........then you'll have a basis for judgment.

After fixing all your problems like valve adjustment and diesel purge injector cleaner set it up to run vegetable oil ( heated of course) and watch how smooth and quiet it gets:)

Mine could almost be confused as a gasser now my system is all bug free.
Steve

The Om602 has hydraulic valves, they don't get adjusted like an OM617. You do check for cam wear, but with 90K I doubt that's an issue unless the car has been abused with poor oil change intervals or oil quality.

The 602 will not shake like an 617 at idle to the point of blowing out air cleaner mounts:P

If the mounts have not been done yet your due. Check the exhaust flange after the headers. It has a tendency to losen up and make noise. Also check out the belt shock & Idler pulley. You may want to look at the flex disks they may be due also.

With good fuel a 602 is very stable and quiet, like the first one you drove.

Yeah but somewhere along the line didnt MB start making ridiculously short-lived fluid filled bladder engine mounts to accomodate really picky people who hate the clatter, shake and rattle of diesel engines? Kinda like their 'diapers' for owners who caint stand a 5" oil spot on the garage floor. Including hood pads and engine vibration dampeners, these all seem like GAY adaptations to me that have nothing to do with improving the quality of the automobile.

Diesels clatter and shake. That is the nature of compression ignition. That is how they tell us they are alive and well.:)

You almost cannot hear the engine in the SDL at idle with the windows up. Certainly at all speeds it sounds far away. Not the electric car smooth of a good W140/220 but darn close.

:D LOL, Yeah somewhere in the late 1900's of the 20th century MB started building "automobiles" that actually got better fuel milage and were faster than tractors;)
But now in the early 21st century MB diesel automobiles are really "GAY", not only diapers,no shaking and quiet, but they don't even smell the same! What with with DI motors and common rail computer controled fuel injection.:wacko: Whats this world coming to:silly:

50/50 biodiesel makes my 123 run gasser quiet.