First time valve adjustment. Need advice
 

Trying to adjust the valves on my sons 123. Problem I'm having is, I can turn the adjustment and lock nuts till I'm blue in the face and no change in clearance. I'm ASSuming that the valve is turning with the adjustment nut? How do I prevent this? I have two valve adjusting wrenches but not the third (that I'm guessing holds the valve still). If it isn't the valve turning what else could I be doing wrong? I checked the clearance on the first valve and it was very very tight. Just got the car and don't know when the valves were done last. How many turns of the nut are we talking for an average adjustment? 1/2 turn? 2 turns? 5 turns?

Any insight is appreciated.

From your description I would also agree that the valve is turning.

You should easily be able to see it spin.

If you do not have the exact size open end to fit on the valve
get a channel lock or some adjustable wrench and have someone hold the valve
while you break loose the nut and lock nut.

It takes very, very little turning of the adjusting nut to create loose to tight
gaps between the lobe and adjusting nut.

Once the valve and lock nut/adjust nut are loosened you should never have trouble
again.
Once I got my too tight valves loose now adjustments are quite easy.

I can't explain it.As the valves wear the valve seat wears.The valve is moving up to the cam.So you are moving the valve down away from cam.So you hold top nut and lossen bottom nut away from cam.Fine tuning is done with adjustment nut (top).However you need to make sure you have enough threads to adjust.It could be possible that the top nut had no room to turn down away from cam.

Hi
www.dieselgiant.com has a nice DIY pictorial on valve adjustment. Are you holding one nut steady while you move the other? A number of other tools can be used to hold the valve from rotating but most folks don't find that a problem.
Good Luck,
Joseph

There are the special valve adj wrenches and additional special tool that you need sometimes. I have found that I only need the additional wrench 1 out 5 valve adjustments.

Just make sure to measure the clearances after you've fully tightened the two nuts back together again. They'll shift a bit as you tighten them together, possibly enough to throw the clearance off.

I have a pair of Hazet valve adj. wrenches so I know I have the right size. I have no problem getting the nuts loose. I can loosen the bottom one 1 turn or so then bring the top nut down to meet it and I still have no change in clearance. I still don't understand how I keep the valve from turning. Do I hold the retainer on top of the spring or stick something through the spring? I can get the wrenches on both nuts at the same time, but where do I put another to hold the valve still?

I followed Dieselgiants tutorial, but he doesn't mention how to hold a spinning valve.

The retainer is indexed to the valve stem. Immobilizing the retainer prevents valve rotation. Jamming a large, flat screwdriver alongside the retainer is a common strategy.

I hold the lock nut (lower one) stationary and crack the adjusting nut (upper) loose, then tighten the locknut about 1/4 to 1/2 turn (it will not lock because by turning it clockwise it will be going further down and away from the top adjusting nut). Now Hold locknut and tighten adjusting nut down on top of it. This will allow you the extra 1/4 to 1/2 turn on the adjusting nut which increases the gap which is what it will need unless some P.O. or "mechanic" has really messed things up and left you with too much clearance as opposed to too little which is the natural order of things if the diesel has been left to its own devices.

If the valve spins, no "adjustment" occurs.

I have no problem getting this far. Problem is I currently have NO gap between cam and pad. After the above procedure I still have no gap. Could they be so tight as to need significant turns to get to an acceptable gap? What about dropping the valve into the engine, I'm worried about that too.

As far as keeping the valve from turning, I can stop it by wedging a flathead along side the valve spring retainer (the six sided keeper on top of the valve spring)? Does this still leave room for the adjusting wrenches?

Thanks all for the help. I know once I get the first one done the rest will be easy!

I have no idea if there is room as I has always had the proper tools. If you do not have at least the special curved wrenches you are going to have some real fun at number 5 cylinder. Baum Tools should sell both wrenches and also the retainer wrench. Well worth the money if you plan to keep on adjusting your valves yourself. At my shop we charge $90/hr and the book calls for 1.7 hrs to adj valves. Food for thought at least. Hope this guides you. The use of proper tools will save you time and money.

I have a set of Hazet Mercedes valve adjusting wrenches. I don't have the wrench that stops the valve from turning. Other than the missing wrench, how else can I stop the valve from turning? I guess Tangofox007's large screwdriver is the next best thing.

Did you try the channel locks? maybe with a sexy attendant holding your tool.

Charlie

Are you sure that you have the cam lobe pointing to about 1 o'clock or whatever DG recommends?

It's been a while since I had my W123 but I think the cam lobe should be pointing to 1 o'clock.