W115 OM616 240D Shaking at Idle - Page 2 - PeachParts Mercedes-Benz Forum

Screwdriva · #16 06-01-2020, 05:46 PM

As I've shared above, vibration only disappears at the highest idle adjustment knob setting and is silky smooth with the slightest throttle. If I had to guess, I'd estimate that to be between 900-1050 rpm. I'm still hoping someone on here has experienced this and has an understanding of how to address it.

Till then, I am about to enter the "rinse phase" of my Auto-RX oil additive - this really improved smoothness on my W123 when I had first purchased it - the result experienced in my OM617 is worth the effort! Fingers crossed!

rocky raccoon · #17 06-01-2020, 06:07 PM

It's never quite as simple as simply increasing idle until shaking goes away. Our engines are inherently smooth, particularly the 5 cylinder ones. One must take the effort to find the source of rough idling.

Assuming that all the mechanical issues are correct, valve adjustment, compression, etc, The remaining sources such as air incursion and dirt in the fuel are all that remain. If you are certain there is no air issue, look closely at your primary fuel filter. ANY sign of dirt, no matter how small you think it is can be the problem. Change the primary filter if not fully clean. If the dirt particles come back quickly, the tank filter needs cleaning/replacing.

Screwdriva · #18 06-01-2020, 07:21 PM

Quote:

Originally Posted by rocky raccoon

Assuming that all the mechanical issues are correct, valve adjustment, compression, etc, The remaining sources such as air incursion and dirt in the fuel are all that remain. If you are certain there is no air issue, look closely at your primary fuel filter. ANY sign of dirt, no matter how small you think it is can be the problem. Change the primary filter if not fully clean. If the dirt particles come back quickly, the tank filter needs cleaning/replacing.

Thanks! All 3 filters are practically new. All sediment from the housing was cleaned when replacing them. I suppose I could try another diesel purge to see if the problem disappears but it didn't the last time.

vwnate1 · #19 06-01-2020, 09:27 PM

I bought an optical tachometer and set the idle to the proper range, I forget what it is but about 800 RPM, engine hot .

Maybe I should set the idle with the car in gear and the AC on ? .

Agreed, the engine is always silky smooth and eager to rev. the *instant* I apply the foot feed .

I don't like overly high idle speeds, it tends to make the tranny slam into gear from neutral and hinders proper down shifting .