W123. Adjusting Valves the easy way. Advise from a Mercedes master to an apprentice - Page 3 - PeachParts Mercedes-Benz Forum

123boy · #1 08-19-2019, 04:27 PM

thanks for the pics and clarification. however, my confusion remains. would not turning the the nut CCW move it closer to the rocker, thereby making the clearance smaller? sorry if I'm not "getting it".
What I'm imagining, I guess, is the top of the valve stem is threaded and the adjusting and lock nuts are threaded onto the valve stem...is this correct?
In essence, by moving the adjusting nut, you're shortening or lengthening the valve stem (or length of the valve), right?

Diesel911 · #2 08-19-2019, 09:56 PM

Quote:

Originally Posted by 123boy

thanks for the pics and clarification. however, my confusion remains. would not turning the the nut CCW move it closer to the rocker, thereby making the clearance smaller? sorry if I'm not "getting it".
What I'm imagining, I guess, is the top of the valve stem is threaded and the adjusting and lock nuts are threaded onto the valve stem...is this correct?
In essence, by moving the adjusting nut, you're shortening or lengthening the valve stem (or length of the valve), right?

Turing the top nut counter clockwise raises it on the valve stem and decreases the clearance. And yes both nuts are and the Valve Stem are threaded.

123boy · #3 08-19-2019, 10:15 PM

Thank you. That's what I thought. These 2 sentences from the original poster are what confused me.

"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."

"If the gap is too loose then use the bent wrench on the UPPER nut and rotate it CLOCKWISE ( looking from above), do not loosen the 2 nuts."

He is stating the exact opposite of what happens when the nuts are turned CCW or CW, hence my confusion and concern. Whether you loosen the 2 nuts, or not, CCW makes the clearance tighter and CW makes the clearance looser (looking from the top, he states). Doesn't matter if you're looking from the top, right, left, front or back. As long as you're not looking from underneath, CCW=tight CW=loose
I'm sure its was just an oversight on the part of the original poster. However, that could create a nightmare for someone not quite sure how it all "works", attempting to adjust their valves for the first time.

Whew! Glad we got that straightened out...now I can sleep

Thanks for the input!

123boy · #4 08-20-2019, 12:06 AM

Thanks "Diesel911"! Appreciate your responses to my queries. Very good advice on this last one, by you.
Thought I had it figured out until I read this thread. Then I started to wonder if there was more to it than I realized. New to these cars and there a many details some with more experience take for granted.
Originally, I was pretty sure which direction to turn the adjusting nut to make the clearances bigger or smaller. But, then again, didn't want to take anything for granted.
Definitely not in a hurry. A good valve adjustment is so rewarding on many levels. The last vehicle I did a valve adjustment on was a twin cam honda. No way you can hurry that job. Kinda lookin forward to just havin 8 valves to spec out. Should be fun! I know the rewards are gonna be huge! LOL
Thank you sir.

PDeputy · #5 10-15-2019, 03:38 AM

Quote:

Originally Posted by dmorrison

Getting my daughters 83 240D ready to head back to Texas A&M on the 21st. She's going to go with it.

Decided to adjust the valves. I don't know about you guys but I've always felt the valve adjustment job to be one of those PITA jobs.
I have the Mercedes Service Manual, The Mercedes valve adjustment tools, The shop etc. etc. etc.
What I find is that when I loosen the top nut, which moves upward, closing the gap. Adjust the bottom nut to specs, (.30 for exaust, .10 for intake cold) and then you have it you tighten the upper nut WHICH CHANGED THE ADJUSTMENT. So you over compensate on the bottom one and then tighten the upper, Oops to much so try it again.
Out of frustration I went the dealer and talked to the W123 "Master". I shall pass on his words of wisdom since it took me 5 minutes to adjust the valve correctly using his method, and 4 of those minutes were rotating the Power Steering Pump bolt to move the camshaft.

He uses only 2 of the adjustment wrenches. One of the bent units and the large base unit.
Position the cam so that it is 180 degrees from the valve as shown in the Service Manual. Place the large base unit on the valve spring keeper washer as you would normally use the tool. Then feel the gap with the feeler gauge.

If the gap is to tight, then use the bent wrench on the LOWER nut and rotate it COUNTER CLOCKWISE ( looking from above) , do not loosen the 2 nuts.

If the gap is to loose then use the bent wrench on the UPPER nut and rotate it CLOCKWISE ( looking from above), do not loosen the 2 nuts.

It may be a firm rotation but it will rotate.

It's like this hugh light

came on. I could not believe how easy it was using his method.

Now this method may be debated, scorned, praised, defended, ridiculed, etc. But it took me 1 hour yesterday and I was not happy with the results. His method took 5 minutes (and as I said 4 of those minutes were waisted rotating the cam) and I was extremely accurate in my adjustment.

Knowing this group, and I do like this group, I'm sure some of you will not like it. But it is the method the dealer uses and he is the top W123 mechanic there.

So---Flame suit on

Dave

Dave,

Adjusted my 300D valves today. Used your method for some, use the factory method for others. When you reference the "large base unit" in your text above, are you referring to the "washer" on top of the spring? That washer is shaped like a very large nut (but as thin as a washer). My problem was getting a spanner wrench to fit the "large nut". I had a 30MM wrench, but it was just little to small. I think I needed a 31MM to easily fit over the nut. Is that how you did it? or did I just make up my own method that was more difficult? When I could hold the nut stationary (and the locking nut was not too tight), your method worked well!! Thanks for the tip.

ykobayashi · #6 10-17-2019, 09:54 AM

Just to toss in my 2 cents. I can never remember which nut to loosen or tighten. Big silver one or little one?

I just relearn it each time. Loosen the lock nut and start spinning nuts while dragging a feeler gauge in the gap. Then it’s like “oh yeah that’s how it works. “

If you go in the wrong direction or turn the wrong nut your feeler gauge will tell you by getting stuck, getting sloppy or not moving at all. If I don’t go in worrying about the exact howtos and just dive in it is easier mentally.

Second I am not afraid to not make the clearances perfect. If you make them a little on the loose side nobody will care or remember in 15,000 miles when they start to tighten up naturally. Drive one of these cars long enough without adjusting and one or more of your valves will eventually be not fully closed.

I use to take this really seriously and get anxious about setting clearances but once I realized it was like regularly raking up leaves on my lawn it got easier. It’ll be fine if it is a shade sloppy just like leaving a couple of leaves because you’re gonna do it again soon enough. You gotta do it but knowing when it’s good enough makes it easier.

Clemson88 · #7 10-20-2019, 09:45 PM

I do the best job I can. If it reads wrong I redo it. Still, this is an art is is not science. I do not think slight variations matter if they are only slight.

I never consider that while I'm working. The goal is always perfection and usually turns out very well. That being said the next time I adjust valves it's likely the engine won't start because none of them will close.

I'm old and I know the FSM method works just fine. After you guys have used this new method over 50K miles let me know. I may try it your way.

Never-the-less, thank you all for your contributions to this thread.

okyoureabeast · #8 10-21-2019, 02:31 AM

I would leave my feeler gauge in while I tightened down on the adjustor. Then once I was satisfied with its clearance I would tighten the top nut on until satisfied.

The feeler maintained a perfect clearance and the bolts didn't get too tight.

Clemson88 · #9 10-21-2019, 07:28 PM

Quote:

Originally Posted by okyoureabeast

I would leave my feeler gauge in while I tightened down on the adjustor. Then once I was satisfied with its clearance I would tighten the top nut on until satisfied.

The feeler maintained a perfect clearance and the bolts didn't get too tight.

You can do something I can't do. If I tried your method the gauge would have a lot of friction on it. I always though the 'feel,' is how you get accuracy.

okyoureabeast · #10 10-22-2019, 11:46 AM

Friction to me was fine so long as it could go in and out at the in spec size.

The real test was adding . 001 to the gauge and trying to put it in. If it didn't go in, then mission accomplished.

Graham · #11 06-18-2020, 12:47 PM

Old thread. I thought I would try the OP's method. But no 31mm wrench. Before making one, used long needle nose vicegrip just for the trial. Well I could not budge the nuts. Decided to go back to what I know how to do

If I would have to slacken tight nuts anyway, what's the point?

Anyway, got it done and back together after lunch today. Adjustment went quickly, because only 3 or 4 valves needed adjustment!