This is above me and really hope one of you have had this problem. I am the proud owner of an 83' 300D w/ 110k. I recently have been experiencing a rather strange idle problem, It seems that my diesel is starving for fuel. It is very easily noticed by the erratic idle surge that can be noticed during a cold start. We all the love the satisfaction of a clean turn over on a cold morning but something is really restricting fuel to the IP. I pulled the tank strainer and cleaned the crud, changed both primary and secondary fuel filters, checked all lines for leaks and have even had the the seats rebuilt in the primer pump, NO CHANGE. I recently replaced the turbo rack damper bolt in the back of the IP to the gold bosh upgrade. I believe the bolt to be tuned properly, but the sweet spot is rather difficult to find. Some have told me this bolt to be the problem, others have told me that I m due for valve adjustment. I have ran a couple injector cleaner solutions through the tank and also directly into the IP. Some have recommended that I use some BG 44K or diesel purge, to give my fuel system a professional cleaning. Its above me, any feedback is helpful

If you haven't adjusted the valves in 15K miles, they are due anyway but that's probably not the issue. I would back out the rack damper some more, until it just starts to shake, and see if the surge goes away. Where is you idle speed set, it should be around 750?

well I did a valve adj. at 107K about a year ago, so it does need to be done but I don't think thats the problem. I have never really tried to set the idle speed, some I'm really unsure of what it is set to. I know some of the older 300D's have a knob to adjust the idle speed, on the dash. My hayne's service manual says that it is a job better left to a dealer on the new diesels, never been there, but I hear its quite expensive. If it a D-I-Y project, I'm down for the challenge. If you know how or a good link please let me know. thanks

If your problem appears after the engine is warmed up, I'll go with an improperly adjusted RD bolt. I've been through this, can be difficult to find the spot.

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83 SD

84 CD

Ive had this same issue.

Idle went rhythmically from 750 to 1000 and then back down again.

It was my rack dampener bolt. I had also recently changed to a gold one. Heres what I did to fix it:

Tools: 12 and 14mm wrenches. Gear wrenches better, but not required.

1.) Engine off, but engine warm (not hot - that oil cooler line can be hot) - take the bolt out. Inspect the rubber gasket ring - make sure its evenly seated around the bolt.
2.) reinstall the bolt, turn till you feel resistance and go an extra turn in.
3.) Engine on...turn bolt until the engine lopes (gets really unsteady)- then make a full turn in. That should be the spot. If you tighten more it may get harder to start. I dont know what the spec is for how tight to make this bolt, i have just used trial and error.

Good luck
dd

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car