My 83 300SD has horrible Vibrations at idle while in drive. As soon as i start going it smooths off. I have always thought it needed motor mounts but someone suggested that the valves need to be adjusted. Any thoughts?

I do not know, but about three years ago, I was considering a white 1984 300SD, with 336K miles. It was a 1-owner, like new car, ZERO rust, but it had a severe shake at idle, so I passed on it. I think he wanted $1800 for it or something. Two weeks later I went and paid $4500 for a 90' Lexus LS400.

I was told a host of things it could be by folks on this very forum. I was told it could be anything from: motor mounts, bad fuel to even bad compression. Even a local MB shop said it could be clogged injectors or clogged filters.

It was recommended that I have a PPI done on it, but I was afraid to drive it that far running like that. With even the slightest acceleration, it would smooth out as smooth as silk. The transmission shifts were very, very harsh and jerky and the car barely had power to pull back up the owners driveway. I had to FLOOR it to keep up 15 mph speed.

It also had a slight radiator leak to top that off, so I passed on it.

Good luck!

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2004 Toyota Sequoia Limited 4wd
1991 Lincoln Town Car Executive
1991 Cadillac Sedan DeVille
1988 Mercedes 300SEL
1972 Chevrolet Caprice Kingswood Estate 9-passenger wagon
1973 Pontiac Grand Ville
(Prior MB's: 1974 240D, 1985 380SE, 1984 190D, 1993 400SEL)

I just bought an 85 300D a little more than a week ago. It vibrates a little at idle but not too badly.

I'm having the valves adjusted on it in the next week since I figure that probably hasn't been done in a few years, so I'll repost to this after it's done to say if it made any difference.

I've been having a rather bad back problem of late...........pain that runs down my right leg............coming from the lower back.........near my hip.

I'm going to go out to the SD and do another valve adjustment........in the valiant hope that my back problem will go away.

A car in need of a valve adjustment will not vibrate due to that. The vibration must be from something else. I'd start with the rack damper screw. Nevertheless, on that particular car, that vibration is nothing to panic over. It won't be a big ticket item, so relax. Get the car tuned to its optimal condition - valve adjustment, clean air and fuel filters, good diesel, possibly treated with some additive - and then start working on the rack damper screw and, if applicable, motor mounts.

86560SEL, I read about that car from one of your older posts. Looking at it now with what I know about these cars, you could have beat the price down to like $1000 - $1200 and had a great car. All those problems you noticed with the car were not big ticket items. Radiator could be replaced for a reasonable price, while valve adjustment, clean filters, etc could have eliminated any engine-performance issues. Then the harsh transmission shifts were probably 100% vacuum related. At the most, with an additional $1500 (if you pay someone to do everything) you could have had a nice ride in the end. We live and learn.

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1999 Mercedes-Benz S600, 103K miles - garage queen
1988 Mercedes-Benz 560SEL, 89K miles - daily driver
2007 Hyundai Sonata Limited, 31K - daily driver

I figure the car needs motor mounts.. as far as filters i change them all on time and i only use BP diesel which around here is 47 cetane not 40. Seems to make a big difference with power and amount of smoke the car puts out. Thanks again

Well, I finally got my car back after having the valves adjusted and a ball joint replaced and I have to say it seems to vibrate less in idle. Also, it shuts down a little more smoothly.

The vibration was not terrible in the first place, though.

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Ralph

1985 300D Turbo, CA model
248,650 miles and counting...

Was it a vibration or a rocking of the engine?

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1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
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