Yeah, I imagine that the engine will always vibrate some, and there's nothing one can do about it. In my case, the vibration is quite severe though. Also, what is particularly disappointing is that revving up the engine a bit makes the engine solid as a rock. I can stand there with the hood open, and pull on the throttle linkage, and see how the vibration disappears almost completely after a small pull. So the engine is capable of not vibrating, at least at higher RPMs. Must be a resonance thing, or something like that.

I'm also contemplating replacing the driver-side engine shock. When I pulled it out during an oil cooler line R&R, it was kinda lifeless (the passenger-side one seemed ok). Searching up on the issue of rough idle and engine shocks turns up conflicting results, however. Some people believe new shocks do help with rough idle, some believe that they are only there to control shaking during engine shutdown. Who knows? Unfortunately, this engine is not in a tip-top shape, so the wisdom of dropping $40 on a new shock is questionable. Valves are adjusted, but I've no idea how good the injectors are. There's also 5 degrees worth of timing chain stretch, and I don't know how far the timing is off. Haven't gotten to those things yet.

Maybe I should have add YMMV* - I have not had to set a damper all the way in, nearly 75% is where they start to do their thing on my vehicles at least. In my experience the idle gets worse if I screw it further in almost to the end of its travel. Your Mileage May Vary*

Of course there are so many variables, the IP itself included. The local Bosch rebuilder tells me that the 5-cyl engines always had a tendency to shake from the first day they were introduced and MB redesigned the bolt to allow better control, the spring is firmer in the gold colored versions.
I can tell you that if you have a leaky valve guide seal it will cause an engine to shake. BTDT. I decided to turn my NA engine in for a turbo transplant after I had seriouos blowby problems, found one valve guide riding up and down, loose in the hole its amazing it didn't crack apart, they were also bronze and not the OE steel guides, clearly the head had been rebuilt by an incompetent place. My point was that engine loped no matter what we tried, being sick I was happy to get rid of it. Sitting at a stop light the car had about a one inch plus and minus displacement, looking at the fenders bouncing up and down I was ashamed to drive the beast. Now that I have a great engine I love the car.

A leaking injector line would surely make it run poor. The test for injectors (and valve seal problems too I suppose) is to loosen the injector lines one at a time, the engine should run worse (ie. lope, etc) as the line is loosened and return to smooth or smoother idle as the line is retightened. Maybe odie should consider performing that test?

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

Do the 603s have the same setup? If so, then my car definitely needs to be adjusted. My idle surges a bit, and the engine speed drops too much and then recovers when it returns to idle.

The reason the engine won't "balance" has to do with the geometry of it, and the forces on the crankshaft. Because of the way the pistons and crankshaft are located as each chamber detonates it causes a rocking motion (the front of the engine goes down, the back goes up) which we know as the vibrations from the engine. As you add more cylinders it smothes out. A V style engine has the same dynamics basically as a straight layout with half the cylinders (a V6 = a I3, V8 = I4, etc). Of course there's all sorts of complications to that like bank angles and what-not.


Hope that made sense, I'm not sure where I read about it, but it's common Automotive Engineering theory, if you'd like to read about it further. All I know is it requires a lot of pictures to understand (at least for me) :/

-Alan

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2005 Audi A4 1.8T CVT -Silver/Black "Siegfried"

1982 300D - Silver/Blue "Ralph" -For Sale:
http://www.peachparts.com/shopforum/mercedes-benz-cars-sale/119226-1982-300d-sale.html#post852260

1989 VW Diesel Jetta Blue/Blue "Bodo" RIP

A 617 will never idle completely smooth. Thanks for supporting my thinking Capt Kirk
However
A properly adjusted 617 with GOOD engine mounts, air cleaner mounts and engine shocks will at idle not show movement of the star as you gaze down the hood. While sitting in the seat your legs will not feel like they are moving or rolling from side to side in any appreciable manner.
Also remember a cold engine is always worse.
After my 300SD is warmed up and I raise the hood I can see only a very small lope from side to side , the air cleaner is relativley stable.
As dieseldiehard noted there are other factors as well, which all must be eliminated to get the best result

VeeDub,
The 603 is a whole 'nother kettle of fish. It has an electronic idle control that is intended to regulate idle as load (like the A/C compressor) is turned on and off. On my 124 (and I issume on most other cars with the 603) at the rear end of the IP there is a round, thin "can" slightly smaller than the end of a soda can with a wire attached to it that controlls the idle. If you pull the wire off with the engine running it should start to idle very roughly. This connects to an electronic contoller and an idle adjustment. On the 124 the idle adjuster is located just above and in front of the fuse box. If you are adjusting it be sure to pull the knob out before turning it, it is not a potentiometer but rather a connector with a series of resisters in it that get connected depending upon how the knob is turned when you push it in. You don't want to break it. By the way, I struggled to get my car to idle right and then discoverd my passenger side engine mount, the one you can't see, was bad. The driver's side mount looked perfect but I replaced them both out of frustration and only realized the offside mount was shot after I pulled it out. It fixed my rough idle problem completely.

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LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold

picture added...does it looked screwed in all the way???

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1987 300TDT
1981 VW MKI Caddy 1.6 diesel, waiting on engine swap
1983 D-50 Power Ram 4x4 "Mitsubishi" 2.3 turbo diesel
assorted gas powered crap and motorcycles

RIP: 1984 300TDT, 1982 300TDT, 1984 190D 2.2, 1992 300D 2.5, 1987 300TDT, 1982 Maxima LD28, 1983 Maxima LD28, Isuzu C223 P'ups X3, 1983 Holiday Rambler 6.2 Banks turbo diesel, 1984 Winnebago LeSharo 2.1 TD, 1985 Allegro 6.5

Just to clarify, part of the test is that if the idle does NOT worsen when you loosen an injector line, you have found a bad injector, because it is spraying poorly whether the line is tight or loose. Correct me if I'm wrong on this.

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'81 300TD turbo <<sold 12/05 to another diesel nut

I've loosened all the injector lines a few times already.

each line seemed to have a negative effect on the idle.

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1987 300TDT
1981 VW MKI Caddy 1.6 diesel, waiting on engine swap
1983 D-50 Power Ram 4x4 "Mitsubishi" 2.3 turbo diesel
assorted gas powered crap and motorcycles

RIP: 1984 300TDT, 1982 300TDT, 1984 190D 2.2, 1992 300D 2.5, 1987 300TDT, 1982 Maxima LD28, 1983 Maxima LD28, Isuzu C223 P'ups X3, 1983 Holiday Rambler 6.2 Banks turbo diesel, 1984 Winnebago LeSharo 2.1 TD, 1985 Allegro 6.5

LRG, I've tried increasing the idle speed a bit with the knob, but that doesn't improve anything. I have read on here that the idle will dip too far down as a part in the IP wears with age. I guess the only solution to that probably would be a new/rebuilt pump. If that's the case, I can live with it until it starts stalling.

Thanks WannaWagon, for clarifying what I forgot to include in the test method. As a final resort at this point, one might want to change the idle speed just a little. Mine is set high for some reason I can't adjust it down any lower than about 750 RPM, the car tends to creep due to the torque converter above its stall speed, it is the '85 that has a higher stall speed spec than earlier ones. I have learned to shift into N at long stop lights. OTOH, it sure idles smooth so I am leaving it alone until I have time to play with it.

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!