Author Topic: Valve Adjustments - What I learned on my first attempt  (Read 367 times)


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  • W116 Enthusiast
  • Location: NY
Valve Adjustments - What I learned on my first attempt
« on: 03 November 2019, 03:23 PM »
Friday, I spent the full day attempting to adjust the valves on my 1980 W116 Turbo Diesel -- which has a rough idle and wasn't in great shape when I bought it last year. Based on the lack of clearance on all of the valves before adjustment, I decided that the valves haven't been adjusted in quite some time. A friend who owns a garage let me use an empty bay and helped by occasionally breaking from his work to advise me and check some of my work --- for which I am tremendously grateful. I've never had to adjust valves before so this was a great learning experience. A few things I figured out:

1) I really could have used the "third wrench" to hold the floats on top of the springs so that the whole valve wouldn't turn. When I tried turning the locking nut the whole valve spun.  It took me a while to figure out that this meant that I wasn't adjusting anything. I finally was ready to give up and decided to look online and "Uncle Ken" had a blurb on his site that mentioned the third wrench and that this is something occasionally needed. Based on his article, I used a pry bar wedged against the float to keep it from moving. That helped, but it still felt wrong to have a crow bar pushing against them.
2) You really want to have two bent 14MM wrenches.  The job probably took me 5x the time needed because I didn't have the right tools. No matter what you do, it just can't be done with two straight  wrenches.  When I have to do it again (in a year or two), I will buy the tools or see if Autozone or somewhere has them available as a loaner. My friend with the garage has the tools (one of the reasons I did the job at his place) but we weren't able to find them. Eventually he broke out a welder and a crappy 14MM wrench and added some bend to the handle. I suspect that he will come to the shop with the correct tools on Monday and say "look what I found at my house". Using the makeshift tools was was far from optimal but made the job possible.
3) I had a hard time keeping the clearance right when locking it in place but decided that however "off" I am, the valve clearances will be notably better than they were. For example, I was targeting .35MM but figured if my exhaust is somewhere between a tight .36MM and very loose .33MM (the feelers I had), it would be "close enough".  Next time I will get a .35MM feeler and try to be more precise. It kills me that we didn't have the right feeler, but hey, whatever I do will be an improvement.

My friend's garage closed at 5PM on the nose, just as I was putting everything back together, so I don't know how good/bad of a job I did. Monday I will open up the shop and try to get everything back together so I can use the car. I am happy to report that the the timing chain was nice and snug and there were no telltale signs of any scraping of the inside of the cover. There also wasn't any notable dirt or sludge.

I am hopeful that this helps the engine feel/sound better and eliminates some of its shake.

Seth Kestenbaum
1929 Model A Ford Phaeton
1969 VW Bug Convertible
1980 300 SD Turbo Diesel getting fixed up
1980 300 SD Turbo Diesel rusty parts donor car