I have a 1983 240D. I have noticed that at idle the car shakes more than it used to. If I touch the accelerator lightly and raise the idle to about 1,000 RPM, the shaking gets much worse and the engine misses and runs horribly. If I accelerate a little further, everything smooths out and the engine runs fine.

There is no noticable decrease in power and acceleration feels strong, (as strong as it gets in a 240D), and smooth. Fuel economy is about 28 to 29 MPG, which seems good.

I just took this car on a 1,900 mile road trip with my wife and did the "Italian Tune Up" multiple times while climbing the hills of Pennsylvania. This had no effect on the miss at 1,000 RPM. Still the same.

Also, worth noting is that the number 4 injector - near the firewall looks wet - like it might be leaking fuel where it screws into the block. Not sure if this could be effecting it. Figured I would mention it since I never saw that before. Also, the valves were just adjusted before going on this trip, so I know the clearances are within spec.

Any ideas? I really appreciate the help. Thanks!

Fix the fuel leak. That can cause rough running from fuel starving.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

The fuel leak might just be the return lines deteriorating. They are generally cloth covered and run in a daisy chain configuration from one injector to the next and then to the fuel return line. It should still be fixed though. Clean up the area and see if you can tell if it's coming from the injector itself or where the return lines are. I just replaced these on my 83 240D. The return line hoses are cheap and easy to fix. They just push on. I overpaid for mine at 12 bucks for 18" at the dealership, i'm sure phil sells it here cheaper.
For the shake i'd check the engine mounts. If it only happens at one rpm spot, thast's got to be it. Also some people have commented that a broken air cleaner mount(yes!) can cause an awful rattle.

Dale 240D

I think I would try and find out which cylinder is the problem by running the engine at a "running rough' RPM, then cracking injector lines and see which one doesnt make a differance. Not so easy with the 4 cyl engs but you might be able to tell, then go from there, check pre chamber, injector, compression.....anyway try and find the problem cyl first. The fuel leak is most likly return hose, not a big deal.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"