Well, I've got one. The engine often idles rough after highway driving, and I've finallly gotten around to searching for the cause. It seems the rack dampening pin is the prime suspect.

I've seen some posters state that the silver ones are an original, defective model. Is this true for all of them? Any chance mine is an aftermarket pin that happens to be silver, or should I just get a gold one? I see they're $83 on Fastlane

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Ralph

1985 300D Turbo, CA model
248,650 miles and counting...

You could try and adjust that pin it might work for you. Just don't screw it in all the way. Mine was that way when I got it and it would not idle on a cold morning but otherwise ran fine.

Same thing here, mine was in all the way, and tight! I had to really wrench it to get it loose Cold starting improved dramatically!

I now have the newer pin....I paid $54 at **************.com, don't know what it is now, I bought it a while ago. It helped stabalize my idle, took a while to "break it in" though...now it works great.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Just so you don't spend money needlesly, the pin only dampens harmonic osilation of the rack. The symptom is a rythmic lopping or surging at idle, not a rough idle. Take out your pin and see if there is still springiness in the tip. In some of the original pins the spring fatigues and collapses. Adjust in just enough to take out the lope. Other idle problems must be addressed first.

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Bob D.
Parrish, FL
1 SDL, 1 D, 1 TD, 1 Mog

Idling rough after highway driving is a pretty telltale failure of this pin acting. Do try to adjust it first. The original pins weren't "defective", but the spring does fatigue with time. The newer, gold colored pin had a much stronger spring than the old one when I replaced mine. As for price, I understand Phil at Fastlane may do better on pricing if you ask. I just checked another reliable online source, and they are selling that exact same pin for $35.50, same as what I paid last year for it there.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Ok, thanks guys. It sounds like the silver pin might last longer than I thought if it isn't already shot. I'll take a look at it and try adjusting it if it's still good.

Just to clarify my idle issue, the idle seems just fine under all circumstances except for after I've driven on the highway for a while. Then, sometimes, the car will shake. Sometimes it's bad enough that everyone is looking at me, sometimes it's not that bad, and other times it doesn't happen at all. I might pull off the highway and be fine at one stoplight but shaking at the next. Recently it's shook more often than not.

I have to say, I love these cars. Have a problem, turn a screw. Great solution! Sure, you can't solve them all that easily, but it goes to show that with the right knowledge most jobs aren't difficult or expensive.

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Ralph

1985 300D Turbo, CA model
248,650 miles and counting...

i just got my 85 300D last april and i'm having the same vibrations going on, i wondering where can i find that damper pin/bolt in the engine?: is it the same as the strut that they call engine shock absorber?

Well I took it out today and it seemed springy and fine, so I put it back in and with the right adjustment, the car is idling much more smoothly and seems to have more power at low rpms. I guess I just didn't know what the power was supposed to be like. My car is the only MB I've driven and I got it a few months ago. I haven't taken it on I-5 yet but it will go out tomorrow.

It even seemed like the up-shifting at low gears was less clunky than usual, but maybe that was my imagination.

It was pretty easy, but if you haven't done it before it might be good to know that if you loosen the nut and the screw just a little, you can probably grab it with your fingers if you stand in front of the car and put your forefinger and thumb around the oil line that goes to the oil filter housing. Otherwise you could waste quite a bit of time uselessly turning a wrench in a tight space....

For a good picture of where the rack dampener pin is, search for a thread called 'Bad Idle when Hot.'

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Ralph

1985 300D Turbo, CA model
248,650 miles and counting...