[Video] 1983 300D Turbo - High shaking at idle
 

https://youtu.be/HoaOi5KCFFw
Automatic transmission.


The turbo/air intake side of the engine shakes violently. I’ve replaced the rubber cushions under the air intake and both the intake and bracket are tightly secure. shaking stops if given a little throttle.


-Engine has all regular maintenance, except valve adjustment.
-Unknown condition of motor mounts.
-Idle is 800 stable
-Runs fine and spirited on highway. Lots of mid/high end power.
-Zero vacuum leaks. Air intake is also all sealed properly.


My first step is to buy valve wrenches and do the tuning. Then motor mounts if that doesn’t help.

If someone has a good ear, please drop some knowledge. Thanks



P.S. - @65mph My rpms sit @2750-2800rpm. Is this appropriate?

Are you sure the air filter bracket isn’t cracked? I believe there’s a reinforced version out there, not sure if it’s legit or works. But if the old bracket shook enough it could have cracked.

I thought around 3000 rpm at 70 was roughly right. I should have looked earlier. It’s been a few years since I’ve routinely drove a w123 with a tach.

The whole Engine needs to shake for the Air Filter to Shake.

After you do the valve adjustment people say to drive 200 miles or so and do the adjustment again.

If the driver's side motor mount is collapsed sometimes the power steering belt cuts through one of the Oil Cooler Hoses and you can loose all of your Oil and after that the Engine.

What I had to do to get rid of the my when Engine hot vibration/shaking:

Raise the Idle speed within the normal range (this helped some; it was around 700rpm). I raised it to about 750 rpms.

I bought a new Rack Damper Bolt but it did not help much. I have a turbocharged 300D Tubo and it has a Rack Damper Bolt.

Rebuilt my Injectors with new Nozzles (This took away most of the shaking)

Doing a Valve Adjustment (took away some more shaking). If you can adjust the Valves yourself do that first except for the new Valve Cover gasket is free.

Changed Motor and Transmission mounts (took away some more vibration)

Found that I had a small air leak that showed up when the Engine was hot due to hard fuel inlet lines that did not seal even with the clamps tight.

Finally was able to use the Rack Damper Bolt to tune out a little more shake. (that bolt was made to reduce the shake on a new engine; not to compensate for a bunch of worn and out of spec parts.

100% solid. Before the video, I replaced a missing rubber mount under the air filter. Also secured one that was loose. I also grabbed the bracket with two hands to find any play; it was solid and secure. I figured the new 3/3 air filter rubber mounts would solve my rattle (because it was the air filter banging metal) but it only made the engine shaking more obvious. In person you can see it well, on iPhone camera, it’s probably 30fps and not capturing the motion, hence the dancing glove.

Thanks for the RPM confirmation. I was worried I didn’t have fourth gear but today I test drove it and it’s certainly there. My 1st gear just shifts too soon, under 2.5k, even in full throttle. Rest of the shifts are smooth...compared to before when I had major vacuum leaks.

i thought mine was running high rpms at that speed too, but then I was reminded that these (82, 83ish) were geared for 55 speed limit days.

Till the shaking is fixed members used to recommends a 6 inch section of heater hose between the Air Filter Housing and the manifold. It works. Can't remember the size of the hose needed.

Noted.



The air filter housing is not banging on anything. After securing 2/3 of the rubber mounts underneath, and making sure the bracket was secure (never was loose), its solid. It just shakes violently with the motor, and more apparent on the air filter.

It’s a big flat mass held on by not too much material. You don’t hear it, and the pipes aren’t vibrating too bad. I think it’s pretty good as-is in reality...

I did the hose thing to mine and it works. Many years later changed the whole air filter and intake system.

My 1985 has slightly taller gearing than my 1984, I recall ~2500 rpm at 65 mph. But even after commuting in it for 19 years, every time I accelerate onto the interstate I keep expecting that final shift that never comes. Why M-B couldn't do better with 4 gears to play with is beyond me. It isn't like they don't have things like autobahns in Germany. I also commute in my 1996 Voyager 4 cyl which has a 3 spd, but maybe spins ~2000 rpm at 65 mph (no tach). Probably it is the switching back and forth between them that frustrates me.