I guess it's time to ask for help again. I have a 84 300d, It's my 1st MB and I don't know want to expect sometimes. I bought it with no engine, and put one in from a bone yard. Tuned it up, put in glow plugs and it really seems to run good. Now the but, it is not real smooth at idle. You can really feel it in the car. I adjusted the buffer screw on the pump it got much better, but it still can be felt in the car when your stopped. The idle speed is 750 RPM by inside tach. There is very little roll after a stop when the brake is released. And it has new mounts. Maybe I'm asking for too much, but I don't how smooth it should be.

If you don't lose tooth fillings at idle, you are OK.

JCD

I think your 750 rpm idle is right on Nscarpi if you're in neutral or park. As a data point, I seem to remember hearing that engaging the car into a drive gear should lower the figure by 200 rpm's too.

I've sat in very nice W123 300D's and besides the diesel clatter, it was difficult to tell the engine was running at idle - very smooth. And that's for a 5-cyl. diesel! Motor mounts are a the key culprit here (and transmission mount if vibration is more pronounced in neutral or park). The smoothess of the drivetrain in these cars is heavily dependent on the rubber mounts supporting them.

My car is in the same boat as yours - engine in a high state of tune, but vibrates too much. Change the two transmission mounts and you'll most likely be amazed.

Actually as a question to others who may chime in: I've noticed another kind of small mount at the rear of my oil pan (which has totally disintingrated over time). What is this little guy exactly?

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'95 E420 - 'Shadowfax' 138kmi.
'92 Volvo 740Turbo Bard 193kmi
'74 240D - 'Ol' Green' 4spd Manual 104kmi. (sold )
'77 300D - 'Red' 223kmi (sold)
'75 240D - 'Bianca the Blue Bomber' (sold)

but I notice that when it gets cold, my 240D could be mistaken for the buckin' bronco ride at Gilley's 'til it warms up. Lucky my 240 has a manual knob controlling idle speed, so you can smooth it out. As a rule of thumb, I'd say that if you can't feel that much shakin' when actually going down the road, you're likely OK. Also helps to shift to neutral at stoplights, etc.

Dieseldude,

That little guy is the "engine stop" if I recall correctly. There is an adjustment protocol for this in my MB manual. I'll try to post the details when I get home this weekend.

JCD

You should try replacing that damper screw on the back of the pump. The pin on the end will wear down to the point where you cant adjust it.

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1983 Mercedes 300SD
1987 Mercedes 300SDL
2001 VW Passat 2.8 AWD
2007 OM642 Jeep WK 4x4