My neighbor is thinking of buying car like mine but it only has 207K. The only concern is that the engine idles rough, yet as soon as you lean on the accelerator, the vibration stops immediately and the engine pulls strong and runs great. The car had no problem at all getting up to 60 mph. I was thinking maybe a motor mount, but I figured I would ask for a second opinon from here.

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1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member

Rick,

I've read up some on various threads and think that the motor mount is the place to start. I purchased a couple but haven't put them in yet. I have the same problem.

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DAILY DRIVERS:
'84 300DT 298k (Aubrey's)
'99.5 Jetta TDI IV 251k (Julie's)
'97 Jetta TDI 127k (Amber's)
'97 Jetta TDI 186k (Matt's)
'96 Passat TDI 237k (Don's
'84 300D 211k Mint (Arne- Undergoing Greasecar Conversion)

SOLD:
'82 240D 229k (Matt's - Converted-300DT w/ 4 speed

Could the idle be set too low?

Frank.

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'82 300SD

There is an update for the rack dampener bolt, also called a mod bolt. Its about $18 from the dealer. The bolt goes into the back of the injection pump on the left rear corner about 2" below the top of the IP. It dampens the IP innards at idle and does so very well. If you haven't done this....HUGE improvement!!!

R&R the bolt, screw it in a little. Start engine and slowly tighten until the engine smooths out. DON'T overdue it, you can go too far and cause other running problems. Just tighten until it smooths. Then tighten the lock nut. BTW don't do this over your new $6,000 driveway, a little oil will leak out in the process.

Eric Eliel
84 300D
381,000
Original Engine
Original Trans.

I have had the very same problem with my '82 300SD. Idle is rough and the car shakes quite a bit. Above 1300rpm and above, the car runs as smoothly as silk and strong. The engine is newly rebuilt and as about 5000 miles on it. I have tried just about everything I can think of. I replaced the motor mounts and the transmission mount, put a new rack dampener screw on the injection pump, installed new fuel injectors, re-adjusted the valves, and re-timed the injection pump. My next step will be to have the injection pump tested and rebuilt if necessary since it was not rebuilt along with the engine. I've always had a sneaking suspicion that the problem is fuel related and I believe I'm close to pinning it down hopefully. I'll let you know when I get this one solved.

My 601 (84 190D) did this. Real rough at idle but ran great at higher rpm's. I tried everything. It turned out to be a bad tensioner and a stretched timing chain that threw it out of whack. In retrospect it makes sense, but I had several shops look at it with different suggestions (including one that said the engine was tired).

Incidently, from that point on I have done all my own work on the vehicle. The problems were at 212,000, it now has 306,000 -- and it still is not tired.

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Jovan

'84 (11/83) 190D 2.2 5-Speed; Silver/Blue; Motor No. 00354, 402k mi (340+kmi mine)

'89 Porsche 911 Turbo Coupe; Black/Black; 53kmi
'05 BMW 530i 6-Speed; 302kmi
'19 Range Rover; 30kmi

For the older diesels (forgot what year) there is no rack dampener bolt.

Don't forget to check the tiny engine shocks.

David

You know, I just had this fixed on my 300D! I had the same problem. First it was the engine mounts, I also had the "rac" adjusted, it was good for about a year. In the hot weather, or after demanding drives, she started shaking again. Another pump adjustment later, all gone! A few months later, same problem. No more adjustment left in the "rac." So, it turns to be the adjustment mechanism (if I can remember right). A new screw (or whatever it was, I really have to check) and its fixed! This seems common. Sorry to be so vague, but I just had a load of stuff done, its hard to remember everything!

My '84 300D ran very rough at idle, causing the enitre car to shake and shimmy like one of those controlled air-shock homie-G cars. I ran a can of diesel purge thru it a few weeks ago, and it idles much, much smoother now!