This 83’ 300DT has had this issue for years. Never could figure it out on my own.
Maybe it’s worse now after I redid the head? It idles great when just slowly putting around town. Only has this prob when braking hard.

Still shakes at idle after adjusting valves, injection timing, replacing fuel filters, purging the injection pump, having Greazzer rebuild injectors, new OFV spring, putting in Lemforeder mounts, adjusting the throttle linkage. What else is there?

I’d compression test, but it idles perfect when not being driven like an ape

Ideas?

I don't see Rack Damper on the list. Suggest doing a search on that term. My wagon had the same annoying issue. Between a valve adjustment and adjusting the rack damper the issue is pretty much gone.

I have replaced the rack damper and those mini shocks before as well, but it was several years ago.
If these were failed, wouldn’t it have shaky idle at all times?

You stop fast the fuel moves. If there is a pocket of air the mass of the fuel can displace it. To have that fast a response the pocket of air would have to be in the injection pump. I would install a clear line from the relief valve to see if any air is showing up.


Of course I am not certain this is the issue. Installing a clear line is not that involved to observe though.

What is your idle speed? On mine there is a sticker that has the min and max idle speed. An engine with some wear on it may need a little more then max idle speed.
re-adjust idle speed and damper. Back out the damper till it has no effect on the idle. Adjust the idle speed. Then slowly turn in the damper screw. The goal is to remove as much shaking as possible with out raising the idle speed.
When I replace my Rack Damper/Governor Idle Pin the old one had a worn tip on it and the spring tension seemed to be about 1/2 as much.

Does your issue only show up after the Engine is up to temp and running say after 15 minutes?

What type of driving do you do. Mine drones around town and seldom gets on the Freeway.

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84 300D, 82 Volvo 244Gl Diesel

Actually he could see if the issue is still there or lessened when he has a full tank of Fuel.

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84 300D, 82 Volvo 244Gl Diesel

I’ve never tinkered with the rack damper. Will research that
Idle speed is at about 6-700.

Only does this after 15 min+ driving. When its cold, it’s nice and stable. Usually I drive 5 street, then hop on the highway for 10 mi. Occurs when I get off the highway hot

From my own experience, my 300TD did not exhibit a constant shake. The shake was intermittent and most pronounced after exiting a highway and promptly being stopped at light.

That could be part of the issue. The Emission Sticker on mine shows 750 plus or minus 50 rpms. You particular engine might benefit from the 800rpms. Some Engines may need higher.

In your case you could leave the rack damper where it is and simply use the Idle Adjusting Screw to raise the Idle to 800 rpm and see what happens.

Attached pic of my emission sticker.

Attached Thumbnails

 

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84 300D, 82 Volvo 244Gl Diesel

I always had my 617 idle around 750-800. Significantly smoother, and better spool up off the line when punching the throttle.

Also sounded better.

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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)

You may want to check your tank screen. Not sure if you meant that when you said you replaced filters. A long time ago a buddy had a rag floating around in his tank that would make the car run rough at odd times when it moved about in there. Just a thought.

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79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles

This is perhaps also typical of a rack damper bolt being worn or out of adjustment. Yet that should not be braking dependent. Read up on the rack damper bolt in the archives. It is adjustable.

Well, didn't go as planned.

I warmed it up, then went to adjust the silver colored RD. Found that it's fully adjusted in, so there's no more to adjust. I backed it out a couple threads just to see if that helps. Will report back after a few miles.

What happens if the bolt is too far IN?