I just completed my first moderate trip. 750 miles round trip. What is the normal drivetrain vibration above 75 mph?

Tires are brand new. Motor mounts are fairly new (less than 10k miles). Driveshaft flex coupling is in good shape.

The vehicle is very smooth up to 65 mph. Starting at ~70 mph a slight vibration becomes noticeable to the driver. At 80 mph it is obvious to the driver. My wife feels nothing unusual in the passenger seat. It can be felt by me through both the steering wheel and the body. I am hesitant to drive it above 80mph due to this.

The engine noise becomes loud over 70 mpg too, which is likely causing oversensitivity on my part to the vibration.

Am I worried over nothing or should I be inspecting anything in particular? How much vibration should this engine make at these speeds/rpms?

Sounds like a tire.Check trans mount too.It smooths out over a 100mph.Tire shops I've found use weights that fly off.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

To disqualify the engine, rev above 4000 rpm in 3rd gear. Do you get the same vibrations? I expect not.

How old/new are the suspension bushings? Steering damper? Idler arm bushing?

Sixto
87 300D

Entire front end is fairly new. Less than 2 years old/5k miles for everything but the steering box which is 5 years old. Brand new shocks and tires. Vibration varies with engine speed. It is very unlikely to be suspension or tire related.

A bad/unbalanced tire would produce far more vibration and be noticeable to the passengers. This was not a dramatic effect. But it was not present 10 mph slower.

Just confirmed in lower gears. The vibration becomes noticeable at around 3.3k rpms. It was less than noted at highway speeds. This could be because the power levels were significantly lower.

I realized that I should have stressed earlier that it was too high a frequency to be wheels or rear drive shafts. Nor was the vibration higher in the steering wheel than in the body of the car.

If this is normal it is not objectionable enough not to ignore it. I am just trying to find out whether it is normal. My experience with diesels were with various larger light and medium duty trucks. With these vehicles I did not notice such an increase in vibration at the higher RPMs.

I just happened to notice this same thing at around 80mph and the only thing I changed before that, were new engine mounts. Any clues?

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Have you reved the engine while you were stopped, up to the RPM`s you notice the viabration?

IE, park brake on and in park or neutral.
could be flex disc or torque converter?

Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

i had a similar issue on a 1983 300sd i had a few years back, i tried everything new tires, balance shocks etc... finally discovered that the little engine shocks were bad and would allow the engine to move uncontrolled in the chassis, replacing the shocks and mounts fixed this.

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1967 250 S
1967 280SE
1968 250S
1971 280 SE
1973 220
1974 280 S
1975 450 SEL
1976 220 D
1979 300SD
1983 300 SD
1985 230 TE euro
1986 280SL
1986 500 SEL euro
1986 190E 2.3
1990 300 SE
2003 C230 K
2004 C230 K
1987 560SEL
1987 300SDL now in canada
2005 C230
1998 C43 AMG Sold to DON
1993 190E 2.6
300TD Former daily driver Totaled
current:
R320 CDI
Ram 2500 Cummins

What's funny is I went for a test drive tonight, up to 90-100ish. Not a single vibration related to what transpired before. My guess now is, as mentioned in the above post, the engine dampers. At idle even with new mounts I can feel a bit of vibration.

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Yeah thats my plan with the new stimulis check.Engine shocks.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran