1983 300D Turbo. (213, 617) I have attempted loosening (6 half turns) on several intake and exhaust valves and although the adjusting nut feels loose, there's no change. I have no clearance. Ideas?

Just to make sure, you do know the top nut is the adjusting nut and the bottom is the lock nut?

You do have the cam rotated so that the lobe of the valve being adjusted points away from where you insert the feeler gauge. ? Just checking.

I am using instructions from
W123. Adjusting Valves the easy way. Advise from a Mercedes master to an apprentice
"If the gap is too tight, then use the bent wrench on the LOWER nut and rotate it COUNTER CLOCKWISE ( looking from above) , do not loosen the 2 nuts."

Yes, cam is rotated to correct position before trying to adjust it.

Those instructions are incorrect, do not use it.

Use THIS guide.

I just adjusted my valves and had this exact problem. Took me a bit to figure out. You have to clamp the large nut that is holding the valve spring down, and hold it so it doesnt rotate (with the valve) when you turn that bottom nut. Otherwise, you don't do anything to the valve height. After figuring this out it was straightforward (other than figuring out what to use to hold this thing.) I used a wide-grip pliers, needle-nose vicegrips might work well. Use your imagination.

you shouldn't have to turn the adjustment screw much to get an adjustment. Maybe a turn or two.

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'79 240D 4 speed manual 105k miles

If you rotate either nut CCW, you will decrease the clearance. Those instructions are hogwash.

To increase clearance, rotate the top nut clockwise. (Loosen the lock nut nut as required.) That effectively shortens the length of the valve stem.

Looks like the problem was the nuts were frozen. There was no clearance at all. Used the dieselgiant instructions (not the quickie version) and it required a suprisingly large amount of force to move the nuts (my husband supplied the actual labor, I'm the typist.)
Anyway, the adjustment went well. Before I was having to do the ignition sequence (turn on the ignition, wait until the glow plug realy clicked (25 seconds) and then try to start the car. Sometimes I'd have to do this 20 times before the car would start, and it would put off a huge plume of white smoke. Now the car starts right up, even when it was 40 degrees this morning (cold for SoCal.) Runs smooth. Thanks for all the good advice.!

I found that a 17mm wrench fits quite nicely between the spring nut and the cam towers.

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