My feeler gages are english units to the thousandth of an inch, they also go to the thousandth of a mm. One is .153mm; since the mercedes only specifies .15 does that include a +/- value? Are the tolerances on a feeler gage better than general rounding i.e. <5 go down 5 and greater go up? Would this be a bad assumption to make? Should I just go borrow metric gages from a friend? This is the first time I've done the valves on this mercedes, so some help would be nice. I've been letting the engine cool down since I had to drive it home but some intake feel pretty loose using the .153, I've been reading quite a bit about this, but some jargan might need explanation if you reply, thank you.
-Nate

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'82 240D, 4-speed, 617 turbo engine

If you have a feeler gauge that is .153 mm., it will be perfectly adequate for a measurement of .150 mm. The error of .003 mm. equates to .0001 inches. The accuracy of the gauge is probably not as close as this.

If you can reliably set the valves to +/- .02 mm., you will be doing just fine.

Please note that you should be setting the valves cold. Cold means letting the engine sit at ambient temperature for 12 hours or more. Don't set them on the same day the vehicle was driven. You would, potentially, be introducing additional error.

Also remember a loose valve is a happy valve.

When the motor is cold the valves are at there tightest, if the gap is to small then on the really cold mornings the car will start harder.

The valves accually get tighter as they wear into the seat.

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82 Rabbit diesel (first d), 84 Jetta turbo d (300k when sold), 83 240d (305k when sold), 84 F250 6.9d w/Banks turbo(parts truck), 86 F250 6 cyl.gasser(waiting for 6.9d), 84 300d ( 347k Sold 8/04), Y2k New Bettle TDI (185k miles), 95 740IL (wifes), 87 300TD (206k Sold 7/05), 05 Passat TDI Wagon

alright, I have a "water temp above 45*C" number and a "water temp below 30*C" number unless I misread it and that's ambient...

Well Anyway, I'll wait a while...like I said this is my first time and I've just been outside playing around with it. I got a few questions now after fiddling around...

Can more than one valve be adjusted in a specific engine position. Like if besides the lift there is a constant radius it should be the same if I set a valve with the cam lobe 180* and not right at 180*. I've read people saying they've done both and never read if it was wrong to do a couple valves at once. Also, what's a good way to make sure it's right, I've been just using the feeler gages the way I was taught, that they shouldn't slide through too easilly but also not too hard, a little drag is good, but is there a foolproof way, like if I dont' trust myself, or is the med amount of drag put it within tolerances?
-Nate

edit: I'm just gonna wait till either tonight or tomorrow anyway... better off because I have a .102mm and a .302 mm so they should be fine.

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'82 240D, 4-speed, 617 turbo engine

If the base circle of the cam is at a constant radius, you should be able to set more than one valve in a given position.

However, somebody has recently looked at this and it may be possible that the base circle is not constant. They got a different result when the cam lobe was directly opposite the rocker arm versus when the cam lobe was slightly off 180 degrees from the rocker arm. This would lead to the conclusion that the base circle is not constant.

The manual calls for setting the valve with the cam lobe 180 degrees from the rocker arm. But, this may be just the typical German way of looking at things, or it may be required.

I think the determination is open right about now. Maybe you could set a valve with the lobe exactly 180 degrees away from the rocker arm and then roll the engine 90 degrees (cam moves 45 degrees) and see if the result holds.

The way you were taught is the correct way. There is no foolproof way. Remember that you probably cannot be off by .001" no matter what procedure you use (probably closer to .0005" with some consistency). This is more than acceptable. People drive these engines with valves that are .004" tight, so, you should not be too concerned with an error of .0005".

do a search on valve adjustment or something like it and you will get a mountain of information....

edited
-Nate

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'82 240D, 4-speed, 617 turbo engine

Nate, it's easy for us to sometimes make the statement "use the search".

Sometimes it is valid because the poster clearly didn't make any effort to learn anything about the topic.

Sometimes it is not, such as in your case, where you inquired about a specific area of the procedure. Attempting to find the relevant posts to your questions would take forever.

But, don't take it personally. William meant no malice, I can assure you.

Sorry cannonball. I assumed if you were asking about .003 millimeters tolerances on a feeler gauge for valve adjustment on a w123 diesel you may not know what you were doing. I assure you I meant now malice as Brian said- and I also assure you you could not feel .003 mm on the feeler gauge unless you've been working with feeler gauges for a cumulatively long time. I feeler gauge engine/gear/shaft alignments to within 2 thousands of an inch as a full time yacht mechanic/engineer for a major builder, with the engines having up to 2000 HP and the shaft being 3 1/2 inches in diameter. Up to 14 grade 8 bolts hold the coupling to the gear, and the coupling is torqued to 480 pounds onto the shaft. (Can't have vibrations at 40 knots.... ) I learned most of this in the last several years, as I have learned about MB diesels in the last several years, from my co-workers, on my own, and here on shop forum from Brian and people of his caliber.

Is it so wrong to ask what tolerances feeler gages are machined to? If I got a .10 gage and it was +/- .001 and I used one that was .002 off then I'm out of specs, yeah like you said not much, but being new at this I need my equipment to be as precise as possible to make up for my human error. I'm sorry I'll delete my other post, but I said I hadn't done it before, I've used feeler gages in the past but it's been years. I didn't say "oh I held up the gage to the sun and it looks like it's off by .002mm, better use another one." And how does assuming I don't know what I'm doing warrant "use the search" comment, obviously you know a lot about using feeler gages, is it too much hastle to fill me in, and perhaps others who search and find this post?

Which brings me to another problem with searching is when I think I find what I need I see 10 replies that say "use the search" and I end up chasing my tail for hours. I know most of this stuff has probably been covered, but a lot of the thread titles are ambiguous and it's not easy to find exactly what one wants. Anyway, I tend to over react...just the e-mail "someone replied to your post" and I reload it to see "use the search" it irked me.
-Nate

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'82 240D, 4-speed, 617 turbo engine

I believe that I mentioned, above, that your questions are perfectly legit, and it was unlikely that you could find any answer to such a question using the search.

However, sometimes a fellow will ask, "How do I set the valves on a 617 engine"?

In this case, most of us will direct him to "use the search" because there are quite a few lengthy posts concerning this procedure and it wouldn't be in the best interests of the person needing the information to restate a foreshortened version.

Sometimes, one of us may state, "use the search" when, in reality, the search would not provide the desired answer. It happens. But, as I previously mentioned, don't take it too seriously. There is a lot of information in the archives. You may benefit by perusing it, even if your specific answer is not found.

And, if you do use the search, and cannot find something, just post again and someone will help you.

The best way to find the tolerances on the feeler gages is to contact the manufacturer of the gages themselves. Anything else is just a guess.

Steve.

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'93 190E/D 2.5 Turbodiesel 5-speed (daily driver)
'87 190D 2.5 Turbo rustbucket - parts car
'84 Dodge Rampage diesel - Land Speed Record Holder
'13 Ram 2500 Diesel
'05 Toyota 4Runner