Hello folks,

I decided to do a valve adjustment today on my 1983 240D. I followed the instructions from dieselgiant.com. I had to bend two 6 inch long 14mm wrenches. I tried to adjust four valves with no success. There was no way for me to loosen the top nut while holding the bottom one still. When I tried to turn either the top or the bottom nut alone both were turning together along with the spring. My question is, how much force is needed to loosen the top nut?! Also, which way I have to turn it to loosen it up?


When I tried to fit the feeler gauge between the rocker arm and the camshaft lobe in all the four valves I tried (two intake and two exhaust) there was no way I could get it through! There was no room at all! I’ve had this car for fourteen years now and I have put only 50k Miles since I bought it and I have never done a valve adjustment! (Shame on me!) I’ve started learning about this car since I started driving it again last May and getting to know it better with the help of all the wonderful folks in this forum.

Again, your advice on this will be great help.

Thank you in advance,
John

if your valves haven't been adjusted in fifty thousand miles..
than the adjusting/locknut are definitely going to be tough to free up from each other,
and there is NO chance your going to get a feeler gauge in there.
remember that it's better to have valves a little loose than a little tight,
they (as you are finding out ) will always tighten with time.

This is usually a leverage problem. You can't get sufficient arm strength on the two wrenches simultaneously.

The top nut must turn counter-clockwise and the bottom nut must turn clockwise. See if you can get the wrenches so that the top handle is slightly clockwise of the bottom handle. Then, you can squeeze the two handles together with one hand. This will immediately break them loose as all the force is directed at the nuts and you've got perfect leverage.

The TOP nut is the adjusting nut.
The BOTTOM nut is the jam-nut.

also, Rightey-tightey, Lefty Loosey applies, as normal.....

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-Justin

I believe in extreme automotive perfection whenever possible.......there is no such thing as "It doesn't matter" !!!

1985 300 CDT - 287k miles

1980 240 D - 340k miles

With extras !!

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You just might have to get a hand. Increase the lengths of the wrenches by welding on extensions or perhaps a couple of short pipe lengths might help as well. Since you quote you cannot get the appropiate feeler gauges in they do need done as you are aware. They are also snugged together pretty well to perform as a jam nut assembley. If you increase leverage make sure the wrenches are a good fit as you do not want to round anything off.

How so? I just did my 240D yesterday. My first time ever. Althought it was impossible to get the feeler gauges in there I had no problems loosening the top nut while holding the bottom one steady. Did I do it wrong? I was also following Dieselgiants instructions.

- Peter.

__________________
2021 Chevrolet Spark
Formerly...
2000 GMC Sonoma
1981 240D 4spd stick. 347000 miles. Deceased Feb 14 2021
2002 Kia Rio. Worst crap on four wheels
1981 240D 4spd stick. 389000 miles.
1984 123 200
1979 116 280S
1972 Cadillac Sedan DeVille
1971 108 280S

The problem is not loosening them, there is plenty of gap to do that. It's adjusting them. The top nut adjusts and the bottom locks.

I love DieselGiants guides, but that's the only one I have an issue with.

you did find cam position before trying to adjust I hope

On one of mine, I took a screwdriver and placed it between the two wrenches, and gave a little twist, and it loosened, with no problems. The others I just squeezed loose with one hand.

__________________
1979 Mercedes 240D (Sold to a neighbor last year,now I have room for a new one,looking for a 300D this time)
1980 Mercedes 240D(bought for a parts car, but I have fun driving it!)

And remember whatever you use on the bottom nut must be ~6mm thick and no thicker. It must be thin or it will hold onto the top nut as well, and you'll screw something up trying to fight it loose.

__________________
'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)