this happens about once or twice a day. so i want to find whats the problem with it.

1984 300SD

changed 2 month ago, primary and secondary fuel filter, ran a can of diesel purge. oil, oil filter, air filter.

maybe like once or twice a day i would come to a stop light and my idle drops down to around 500 RPM. as the light turns green i would put the pedal to the metal and the engine would go up to about 900-1000RPM and stay there. for like 4-5 seconds. so my car doesn't really want to go at all. after a couple of seconds (when it reaches ~2000RPM). it would go fine.

if i notice the drop when the light is red i pop it in neutral and rev it a couple times. i notice the engine will shake a lot. some times after a couple of revs it will clear this problem and it will take off fine.

just wondering what could be the problem. i always thought maybe the injectors are clogged? i ordered some dielsel purged yesterday. thanks for any advices.

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198? 300D ???K - Future DD
1989 300TE 285K - traded in '12
1984 300SD 186K - Sold in 08
1978 300SD 330K - Died in 05

Not sure, but you should look to be sure your linkage is not worn,sloppy or binding.... then go from there....might want to give it some white lube also... in the sockets..

Ned2683.
Try loosening the filler cap and see if the problem persists, could be that the tank vent is plugged.

the linkage(s) looks good. i'll try to drive around a day with out the filler cap and see if it is better. thanks for the suggestion.

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198? 300D ???K - Future DD
1989 300TE 285K - traded in '12
1984 300SD 186K - Sold in 08
1978 300SD 330K - Died in 05

WHen checking that linkage pay close attention to the cruise control linkage arms. Seems they are prone to binding.
I had to remove them and straighten them to get them to function properly.

ned - when you say your idle goes to 500 sometimes - where is it normally? should it not be about 750-800 rpm? - methinks then the linkage would not be the culprit. does your ip have the original rack pin or was it changed? just throwing out things here ..

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1984 300D Turbo - 231k....totalled 11/30/07 RIP

84300DT-normally it idles around 750-800RPM. it will do this all day but once or twice at the stop light. plus what you just said about the IP thing i have no clue .

the PO has no paperwork or anything.

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198? 300D ???K - Future DD
1989 300TE 285K - traded in '12
1984 300SD 186K - Sold in 08
1978 300SD 330K - Died in 05

ok then i would change where you buy fuel and try another place for a tank. your diesel purge should rule out a clogged injector.
if your rack pin is original (it's on the firewall side of the ip underneath the shutoff valve) it will be very apparent if it is original - ie the same corrosion on the suface as the rest of the ip.

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1984 300D Turbo - 231k....totalled 11/30/07 RIP

interesting thing you posted. this all kinda started when i gassed up at this one place. i suspected it was bad fuel. this tank i am running is from the normal place i usually gas up. when i open the filler cap the inside was all rusty. so could this be that they had old/bad diesel? and now my injectors are clogged still? i'll try to run another can or purge through.

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198? 300D ???K - Future DD
1989 300TE 285K - traded in '12
1984 300SD 186K - Sold in 08
1978 300SD 330K - Died in 05

yeah i think it could be.. try to get up on the highway .. do an italian tuneup, run that old fuel out and fill up at an amoco or whatever one has the highest volume of diesel sales near you. then see what happens and monitor the state if the pre-fuel filter and change if necessary.
you can run another diesel purge through to be sure.

i just went 3000 miles in one week to fla and back here to ct, using all kinds of different fuel from no-name to brand name and virtually every one was different in power/mileage etc. prettiy interesting, but fortunately all were 'clean' so i did not have any fuel related mechanical issues.

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1984 300D Turbo - 231k....totalled 11/30/07 RIP

you had fuel lines off to run your diesel purge, sounds to me like you may have a suction side leak, letting air into the system. check you hose connections.

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matt

will do too. thanks.

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198? 300D ???K - Future DD
1989 300TE 285K - traded in '12
1984 300SD 186K - Sold in 08
1978 300SD 330K - Died in 05

i double checked everything and the problem is still there.

when i remove the filler cap it depressurizes (either more pressure inside the gas tank, or viseversa). is this suppose to happen?

do u suppose it was the valves? i didn't think it was because if they are too tight then it would run rough in general not a couple of times at the stop light .

i checked all fuel lines. ran 2 cans of diesel purge through it too.

please help.

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198? 300D ???K - Future DD
1989 300TE 285K - traded in '12
1984 300SD 186K - Sold in 08
1978 300SD 330K - Died in 05

maybe what tom said is the problem - the tank vent is plugged. i haven't a clue where that is though.. sorry.

i know when i remove my fuel filler cap there is never any noticeable 'pressure' being released like on a gas car.

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1984 300D Turbo - 231k....totalled 11/30/07 RIP

how would i be able to locate this vent and clean it out?

yeah he tank seems to build pressure after about 15 mins of driving. i'll try to fix that.

__________________
198? 300D ???K - Future DD
1989 300TE 285K - traded in '12
1984 300SD 186K - Sold in 08
1978 300SD 330K - Died in 05