Diesel RVs: Re: [diesel_mercedes] Valve Adjustment Adventures

Caitlin,

I'm sorry to read you didn't have greater success on adjusting the valves. And it occurred to me that for most of us, the Mercedes iron head diesel was not our first experience at setting valve lash. I suspect many of us learned on air-cooled VW bugs, slant-six MoPars, Ford 200s or something French or Italian or British (possibly even a British motorcycle). All simple, push-rod engines. Even later overhead cam engines, like Honda Civics or Mitsubishi-built Dodge Colts are pretty easy to set the lash. You need maybe two wrenches, sometimes one, or a wrench and a screwdriver. Heck, even MB's own overhead cam gassers from the 50's-60's required only a single wrench to twist the pivot point at the cam follower (aka, rocker arm). (It requires a special, crows-foot style wrench, supplied by Hazet, but, a single wrench, non-the-less.)

On those cars, you aren't working with valves that turn on you, or, rarely, such thin gap guages that can crinkle up. You know, with certainty, when the gap is correct.

It's been a while since I first set the valves on an MB Oel Motor and I almost forgot thinking, at the time, just how difficult I thought the task was, as compared to all the many engines I'd messed with over the preceding 30- or so years before. Even the Harley Irontop is easier (and that's done by FEEL!).

I did then and still use only the standard Craftsmen wrenches to do this job. I've only had a couple of twisty valves, and managed to work through them and get them set. So, I know you don't HAVE to have the special three-wrench set. But that doesn't mean having that set wouldn't make the job easier for me, and possibly do-able for a novice.

There was a gentleman on this list in Chicago that used to make them for list members. I know he sold his beautiful coupe, and has most likely left this list ('cuz by now, he would have offered to make up another batch). I'm sure Tom Hanson at the Classic Center can get them.

As for turning the engine over by using the power steering pulley; I've had mixed success with that. I usually bump with the starter, like you did. On the '79 SD, I can get a socket and ratchet on the crank pulley.

So, at least you got to see what goes on under that cam cover. When you have your mechanic do the job, at the minimum, try to get him to let you watch him do it. Pay him extra, bribe him with cookies or brownies or Ukrainian vodka or something. Watching someone do this would be invaluable for you.

And you DID try. Good for you!

Mark in Lakewood, CO

From: "CaitlinDean" <tinymachine@gmail.com>
To: "diesel mercedes" <diesel_mercedes@yahoogroups.com>
Sent: Thursday, January 5, 2012 12:03:30 PM
Subject: [diesel_mercedes] Valve Adjustment Adventures

Let's just start by saying "you win some, you lose some" ;)

Despite excellent help here and around the interwebz, I hit 3 "rough spots" and was not able to complete the job, and threw in the shop rag. Despite a lot of frustration, I still learned a lot during my attempt, and will be ready by the next time it needs doing ;)

My first "trouble"...getting the valve cover off:
Couldn't *quite* figure out how to minimize throttle linkage dis-assembly (or maybe that WAS minimal) so after taking apart 4 links, we unbolted the entire throttle linkage assembly from the top of the valve cover and set it aside on the top of the air filter assembly. Easy enough. However, we had the hardest time getting the cover to lift up past some of the injector hard lines (one in particular @ cyl 3). The benefit of all that wrestling is that I finally noticed something pretty obvious...that the spacers between the first 3 hard lines were all missing. The bottom of the air filter assembly seemed awfully close (and a little banged up near) to to valve cover and between that and the hard lines it was a lot of wiggling, pulling, angling and deep breathing to get the cover off...but finally...done.

My 2nd "trouble"...turning the engine
I tried via the P/S nut and I think we moved the cam lobes by 15deg or less. I had just had all the belts replaced, and opted to explore other methods before adjusting the belt tightness. The "bump it with the key" method, I just want to clear up, requires undoing the glow timer relay (this is via mercedessource and resembles a method mentioned in the manual), but I didn't get far enough to even really try that either ;)

My 3rd "trouble" ... spinning springs:
I decided to just try one of the valves as the lobe was already pointing up. The spring and collar nut kept spinning. Tried jamming a screwdriver to hold it in place (another M.S. tip) but couldn't really get that to work (I didn't have a big enough tool to do it right). I know there is some OEM tool that holds these guys in place, but I didn't have it :) My friend helping me, *really* wanted to help, and got the nuts unlocked at some point...and then we fiddled with the adjustment, definitely not finding the right "spot" (all the while dealing with intermittent spinning). And then I tried to get it locked up again, and am pretty sure that was unsuccessful.

We'd been at it a couple hours by then, sun started setting (we were outside at his place), was actually getting cold, and I made the decision to put it all back together and kindly ask my mechanic to bail me out of my jam. Putting the valve cover back ON was worse than getting it OFF (new gasket kept popping), but the throttle stuff was easier than I thought...just like a puzzle.

So...I gave it a shot...and I didn't want to call it a total "failure". I have some money from christmas set aside specifically for the car, and I'm glad I have that. I'm now on the lookout for PaP hard lines or at least the spacers. I don't mind picking up the "special tool" that prevents the spinning in place. And I'm hoping to find a pal with a garage ;)

Anyway it was really cool to have the valve cover off and to see inside that part of the engine.

Maybe next year?
Caitlin
Santa Fe