We recently drove about 14 hours round trip in my wife's 81-300sd. On the way back, the idle was very rough at stop lights. Then it would idle rough about every other time we stopped at lights.

I adjusted the valves 2 weeks ago and the filters have less than 2k on them and the small one looks clear.

I order another damper pin but have not put in yet. Could that be it?

Funny thing...the vacuum locks started acting up at the same time...any connection?


Thanks as always,

Don

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84-300D 256K
81-300SD 217K (Wife's)
79-300CD 212K - Project
89-Volvo 245 305K

Check your vacuum lines. Remember the engine shut down is done through a vacuum switch, so if there is a leak or a clog, that switch can be pulling the injection pump shut down half way, giving your rough idle.

Good luck!

Sorry, you may be thinking in reverse on the vacuum shut down. Applying vacuum to the switch causes it to shut off fuel not removal of vacuum.

You are probably on the right track with the rack dampner pin for an intermittent rough idle. Another thing I have found that helps is to run some B20 biodiesel through it.

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Sam

84 300SD 350K+ miles ( Blue Belle )

The rough idle you have sounds like a rack dampener issue to me. I had the same kind of issue and was floored by how well the car performed after I adjusted it correctly.

I'm thinking the locks acting up at the same time is just a coincidence. Are they still acting that way or was it a temporary condition?

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Ralph

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

you might also recheck your valves. a valve that is a bit too tight on a long trip might get hot and hold itself partway open. then leak on a stop til it cools down.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Air bubbles in the prefilter?

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http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

Thanks for the responses. I will replace the damper pin since I have a new one. I guess it could be a tight valve, but I tried to go a little loose rather than tight.

There are a few bubbles in the fuel filter...it always has. What does that indicate?

Thanks,

Don

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84-300D 256K
81-300SD 217K (Wife's)
79-300CD 212K - Project
89-Volvo 245 305K

If it was a heavily city driven car, it's possible that the long highway drive rearranged some carbon, and that's what's causing the rough idle. See if it continues after a few "Italian Tuneups" (foot to the floor acceleration from 0 mph to cruising speed).

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.