The dreaded rough idle
 

Hi Gentlemen,

I have a 83 300D turbo diesel "The Panzer" that I've owned for 5 years.

It has always been a bit rough while idling especially under load (ie, AC on, and in gear). I'm sick of it and have been trying to get it under control.

In 3 months I've had:

-Valves adjusted
-Fuel filters replaced
-Dampening screw replaced and adjusted
-Fuel injectors replaced
-A motor mount replaced (this was about 12 months ago)


The shakes are just as bad as ever. Again, if you drop it into neutral, most of the shake goes away. As the car gets warmer it gets a bit worse.

The idle speed is ok according to my mechanic who is a German expat with a lifetime of Mercedes repair but the tach is dead.

Can anyone suggest the next course of action? Vacuum or EGR valvue issues? Bad cylinder(s)? Other? Other than the idle, and it's knack for destroying AC compressors, the car runs well.

Many thanks in advance,
Matt

Try slowly pushing the "STOP" lever. If before the motor dies you find a slower speed where it doesn't shake, adjust the idle speed down. Also readjust the rack dampener at the same time.

Thanks Steve. It would be crazy to think that I spent hundreds of dollars and all it needs is an idle adjustment but it is possible. I'll give it a shot.

Oh edit: BTW, if I give it gas while holding the brake down, the roughness goes away so if anything the idle may be low.
Matt

The most common fault I see with loping idle is the speed is too high.