I have recently picked up a 1983 Mercedes 240d w123. I have been going through the basics and can't seem to improve or slow down a crazy vibration problem. I have replaced all 3 motor mounts, trans mount, adjusted the valves and have replaced all 4 fuel injectors(injectors were leaking). Nothing has seemed to make any type of improvement. My question is, is there a certain procedure for installing new mounts on this car? I have seen many posts that ask if they were installed with the car lifted in the air or sitting on the ground, does it make a difference? I would also like some advise on the type of mounts that should be purchased if the OEM are not available. Any help would be greatly appreciated.

Have you taken a wrench, while idling, and cracked loose the fuel line to each injector, one at a time, to isolate to a particular cylinder?

Also, have you only done one valve adjustment? If it has been a while, a second adjustment may improve things.

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Sam

84 300SD 350K+ miles ( Blue Belle )

Driveshaft get disconnected and reconnected lately?

Flex discs getting worn?... replace before those blow!

A wheel is out of balance? ...threw a weight, sudden change

Flex plate on the back of the engine? ..maybe.

Does it happen when coasting in neutral too? Try to determine if it's rolling gear, or engine / tranny related.

..under load, or little load?

A wheel bearing?

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Cheers!
Scott McPhee

1987 300D

I have taken a wrench to the injectors and cracked them one at a time with no improvement, idle changed with each injector. I have done a diesel purge and checked the timing chain for wear, though with only 85000 miles it didn't seem likely. The problem only occurs when at a stop in gear, though there is mild shaking in park, it is far worse in gear. I did the valve adjustment about 3 weeks ago and that did not make any difference either.

I think you're getting led a bit astray... Vibrating at idle in gear is probably going to be mounts but possibly a few other things. I'd double check the mounts first though. Certainly if it was an off-brand like Uro.

I think Phoenix brand is the current favorite on mounts.

Forgot to ask if you've run anything from just a bottle, bypassing the tank. If it smooths out with Diesel Purge or even canola (fresh), then that can be a big clue. Since you've gone through the fuel side then you might dig into a compression problem.

-Rog

Have you checked the rack damper bolt? Maybe turn it 20 degrees further in and see if that makes a difference, if not, then put it back.

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'83 300DTurbo http://badges.fuelly.com/images/smallsig-us/318559.png

Broadband: more lies faster.

85000 Miles. Is that a genuine mileage? Not 1085000?

- Peter.

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2021 Chevrolet Spark
Formerly...
2000 GMC Sonoma
1981 240D 4spd stick. 347000 miles. Deceased Feb 14 2021
2002 Kia Rio. Worst crap on four wheels
1981 240D 4spd stick. 389000 miles.
1984 123 200
1979 116 280S
1972 Cadillac Sedan DeVille
1971 108 280S

A few thoughts: I assume that when you changed injectors, that was a full change, including the nozzles as well. From my readings, I think there's debate whether the Bosio or Monark nozzles are the way to go, but from what I've read (here and elsewhere), nozzle swaps have stopped the "shakes" in their tracks.

You mentioned you've done the diesel purge, but is it possible the fuel tank is full of muck, and even though you have "cleaned" the fuel system via purge, new garbage has gotten yanked into the system via the fuel tank? Wonder if trying to run the vehicle on a "clean" tank (some kind of plastic bottle placed in the engine bay) would help. If it does, I'm guessing the tank (more specifically the gunk in it) could be the culprit.

One thing to note is that I've seen "shaking" threads go on for ten pages. It can often be mysterious. About the only times I've seen them resolved is when it's something easy like mounts, getting the gold rack damper bolt, doing a diesel purge, or adjusting the valves, all of which are the standard answers whenever a thread comes up discussing ANY problem. It almost makes me nauseous to even suggest those things. Sometimes they work, a lot of times they don't.

But, go with the easy stuff first. If you figure it out don't forget to post the solution. Sometimes it's even something weird, like mine had a hard vibration through the whole car and I figured out it was the stupid air cleaner that had no more of its mounts left. It was basically a ten-pound weight banging around, so it was no surprise in hindsight.

-Rog

Thanks for all the feedback. I have run it off of a bottle and no improvement. I did purchase uro mounts so maybe that is an issue. That does pose another question, is there a specific way the mounts are installed or a specific order? Does it matter if the car is on a rack or on the ground? Im pretty much stumped. When I replaced the injectors it was a complete swap using OEM parts.

There is no rack damper bolt on a 240 (OM616).

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1985 R107 300SLD TURBODIESEL
2005 E320 CDI (daily)

LOTS of parts for sale!


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Sanden Instalation Guide (post 11):
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I don't personally think it matters, but there may be some merit in letting the engine and mounts settle together before tightening the bolts. You would partially install the mount bolts (just tight enough that they won't fall out but the mount can still move with a little force) and then run the engine for a few seconds. Then tighten the bolts. I don't think it would have as much to do with vibration but rather longevity of the mounts since they wouldn't have any extra strain on them. Especially if you had to push the engine around to get the holes lined up.

If they're Uro brand then that's a huge suspect. Many have reported complete failure of Uro rubber parts within days or weeks, and the initial robustness can be poor to begin with.

-Rog

Wait, wait, wait...Betsie has had terrible, make-you-seasick-at-idle, visibly-rock-the-car-left-to-right vibration when I bought her. I was able to adjust most of it out with the rack damper bolt and new engine mounts (and transmission mount), but she always did shake. At some stoplights more than others.

I was actually driving her to work this morning and consciously noticed that she wasn't shaking at all while I sat a stop light. "Huh", I thought, "maybe it fixed itself".

But....I fixed my air cleaner mounts finally last month. And haven really driven her since then up until today.

Could it really have been the air cleaner fixing the last of it?

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"The MB W123 is so bulletproof, you can drive them forever. Which is a good thing as it takes that long to get anywhere."
Betsie: 1984 W123 300D (hobby, 280k miles)
Myrla: 2001 Mazda Protege 2.0 ES 5spd (daily driver, 130k miles)
The Turd: 2007 Toyota Camry (wife's car, 118k miles)

I had just put my car all back together after a pretty hard front end hit and when I started it for the first time after all that I was sick that it sounded and felt like a jackhammer. I started wondering if it had suffered internal engine damage. Nope, just that ^@#$% %*&% %*@#$ air cleaner.

Actually ended up ditching that dumb thing, but that's a whole other discussion.

-Rog

Clerify the replaced injectors. If replaced with used injectors from another vehicle they could be suspect.
The stock Injector Nozzles have some tiny passages in the tips that get entirly plugged with diesel. I don't believe any diesel purge is going to disloge it.

Uneven compression can cause shaking.

If your idles speed is too low it will also shake.

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84 300D, 82 Volvo 244Gl Diesel