After reading extensively on valve adjustment, I decided to give it a try on my '80 300SD yesterday. Many have claimed a smoother idle, even smoother shifting - since I bought my benz it's idled really rough, smoked a bit excessively on initial startup, and I'm lacking power in the lower speeds, so I figured it couldn't hurt. Recently bought a handmade set of bent wrenches, got the valve cover gasket, printed off my intake/exhaust sheet so I could mark everything off, parked it where I wanted to work on it, and got to work yesterday at about 7:30. Here's my blues song...

(Note: I am not experienced at mechanical work, but I've been able to do basic stuff like replacing fuel filters, return lines, oil cooler, aux fan, blower motor and window repair, that's about it...just wanted to clarify that so you don't rule out something really stupid that I've done)

8:00 Finally figured out the best way to remove the necessary throttle linkage and got the valve cover off.

8:30 No problem using the flat parts near the power steering bolt to turn engine over (clockwise so the fan rotated in the proper direction). I did notice a weird sound coming from somewhere seemingly down below the power steering pump, and I also noticed that the difficulty of rotating the engine was not consistent - some times it would make that noise and be really hard to turn, other times it was almost effortless. Anyway, I set cam lobe at 180 degrees from rocker arm as described in threads (about the 1:00 position). Measured clearance, .33mm, held the top nut, loosened the bottom one, held the bottom one still while adjusting the top to specification, then held top nut in position while tightening the bottom nut back. Or that's what I wanted to do, but I was having lots of trouble getting the wrench to fit on the bottom nut, and then when it did, it seemed like it was too loose.

9:30 Gave up trying to work in tight spaces and removed the hard fuel lines and return lines. Left glow plugs in - that ok? I read somewhere about someone recommending removing them first, but I didn't want to get in deeper than I had to.

10:00 2 or 3 valves later, still nigh impossible adjusting the clearance.

10:30 Took a sanity break (remembering from the threads that I should have already been done by now) and worked on window issue.

11:00 Spent next hour tracking down a grinder and grinding down the bottom bent wrench - helped tremendously. Some of the valves were actually fairly easy and I started feeling pretty good about it.

12:30 After a brief lunch, continued...on about valve 6 of 10. Consistent problem - After I would set the top nut for the proper clearance, hold it still while tightening the bottom nut, almost always when I double checked it it would be too tight even though I didn't move that top nut. So I started having to set it too loose so that when I tightened it would be correct.

1:30 Stuck on valve 9 (going down the line, exhaust I think) due to lack of room. Bent wrenches seemed too long, ended up having better luck with one bent wrench and a small straight wrench. Took seriously 45 minutes to adjust that one damn valve. (Had another sanity window break in there somewhere)

3:00 Finished all the valves, began to double check. Got 3 valves in, all correct, then suddenly couldn't turn the engine anymore cause the belt started slipping. Didn't know how to tighten the belt (again, newbie here), so made the decision to call it quits and hope for the best. Reassembled everything (including new gasket) with no problems, using digital photos I'd taken. The only part of the job that went as planned.

4:00 Cranked it. Realized my fuel lines had been emptied, so primed it (newly replaced new black manual primer) about twenty pushes, finally cranked up. TERRIBLE idle, much shakier than before, more white smoke from tailpipe that didn't go away, and an alarming amount of smoke when I open the oil cap. (Excuse the awful belt squealing on the video, the two drive belts that are beside each other and identical are old and worn and need to be replaced badly. Already have the belts, just need to learn how to replace...but it's not the core issue I don't think cause it was like this before the valve adjustment). Twice after giving it throttle and then releasing, it shut off like in the second video.

5:00 Rehydrated (it was hot down here in Tennessee) and strongly considered whether I wanted to 1) quit trying to be a mechanic and sell the car for scrap, 2) just take it into the shop and let a real mechanic figure it all out, or 3) get back on here and try to figure out what in the hell I messed up. Though I initially chose the latter, I'm not convinced. There are plenty of other things wrong with the car - leaking trunk seal that I've already tried to fix once, a sizable rust spot that's pitted through on the rear quarter panel (200 bucks to get new sheet metal over that section, already have the paint), really bad but not yet leaking windshield seals and aluminum trim both front and rear, and both busted inner boots on the rear CV axle which have started to affect the bearing or something to give this grinding noise on right turns. And another busted air cleaner bracket, probably from all the severe vibrations this engine puts off. So this was one of those days where I had to weigh my love of these good old cars (and future use of biodiesel from a nearby lab) and the frustration with my increasing repertoire of failed mechanical attempts.

6:30 Poured a nice cold Gerst beer to end the day, promptly spilled it all over the living room floor.

7:00 Punched hole in bedroom door (yes, embarrassing, I know, but blues ain't pretty)

7:05 Bandaged bleeding knuckles

7:30 Sat down to pizza and a movie. Turns out Cowboys and Aliens was as bad as I thought it would be. And that's the end of a long day and a 2-3 hour valve adjustment that took 7 hours and made things worse!

Any ideas as to what went wrong and what I should try next? Only thing I can figure is either I pushed on the valves too hard while trying to get the wrench to fit on, or something went wrong during the disassembly/reassembly of the fuel lines. Any help is much appreciated!

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1980 300SD Turbo Diesel
"Bailey's. Mmm...creamy. Soft, creamy beige." - Old Gregg

Should have had the beer FIRST.

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1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD

im not entirely convinced you fuel system is fully primed. how long did you run it? did you have all of the lines cracked when priming?

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have no worries.....President Obama swears "If you like your gun, you can keep it

Agreed. You might light the engine and open each hard line at the injector to bleed air out. It's tough to compress air up the pressure required to pop an injector.

Opening the injector lines while running often takes only about 1/32 of a turn. Let the air / fuel hiss and fizz until its pure fuel and tighten. On to the next.

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1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."

I'm not sure how a valve adjustment can result in white smoke, but maybe some of the experts here can chime in on that. It does appear from your description to be more of a fuel problem than a valve problem.

Try bleeding the injectors like some of the guys here say. FWIW, I've managed to adjust my valves with the hard lines on. In my case the biggest problem faced was trying to get the valve cover back on. The valves themselves were easy, with only one spring turning on me. I just jammed a screwdriver against it and it held well enough for me to adjust that valve.

You had no springs turn on you? That's the one that requires the third wrench.

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1987 300TD
1984 300D
755,000 KM and going strong
BC Canada

Aha, that sounds very plausible. I didn't run it for very long, and no I didn't think to crack the fuel lines when priming. I should have already learned this from when I changed the fuel filters...I guess as soon as it actually started up I assumed it wasn't a priming issue. Silly me. I'll try that first thing tomorrow morning.

As far as the third wrench and the spring turning, I did notice occasionally that the spring would turn ever so slightly even if I was trying to work the other wrenches properly. Maybe that was why it took me two or three times to get the clearance right after tightening. I even turned one intentionally a couple of times (not more than 10 or 15 degrees) so I could get the wrench on. Have I potentially done damage there by turning those springs (again, only very slightly, but...)?

Thanks all! I'll post the results when I bleed those lines. In the meantime, here are the clearances before I adjusted them.
[Starting with cylinder one, E.33, I.10, I.05, E.33, E.35, I.065, I.065, E.23, E.33, I.10]

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1980 300SD Turbo Diesel
"Bailey's. Mmm...creamy. Soft, creamy beige." - Old Gregg

Recent personal experience here. I adjusted the valves on my '84 300TD a few weeks ago and didn't have too much trouble. This was the first time I had adjusted the valves on anything by myself. Car ran okay beforehand, but had quite a bit of clatter at idle, some shake, and the valve noise was a bit more pronounced at high rpm - very clear at 80mph. After the valve adjustment, the car was much smoother and quieter. I did notice a bit more low end torque, also.

I bought an OEM set of valve wrenches, including the third one for holding the valve still while adjusting, and they made the job very simple.

Concerning what you said about holding the top nut while tightening the bottom nut: I tried it like this to begin with, but found that this method didn't work very well; like you said, the clearance would be correct, then you tighten the bottom nut, then the clearance would be tight.

What I did was tighten both nuts at the same time (the bottom wrench tightening at a quicker pace than the top nut) while simultaneously sliding my feeler gauge between the cam and the rocker arm. It sounds weird but you kind of get a feel for it. Using this technique allowed me to tighten down the nuts at the exact moment the clearance was perfect.

In addition, I did the job without having to remove anything besides undoing some throttle linkage pieces and obviously, the valve cover.

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1984 300TD Turbodiesel - 272k
- Daily Duty
1985 300D Turbodiesel - 315k
- "Recommended for competition events only"

I had a bad day yesterday too. IN working on my race car I inadvertantly hooked up the battery backwards and fried my guages and I don't know what else yet.

I woke up at 4 this morning and the realization that the cables were backwards came to me.

Good luck on your car. You can run a diesel on wd40 sprayed into the intake to get your pumps primed. It will run on it as long as you keep spraying it in.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

The noise is air compressing and escaping. When you are turning the engine, sometimes you are compressing air (difficult) and sometimes you are not (easy).

When you tighten the lock nut, you push the adjusting top nut upwards in the thread, making the valve clearance smaller. So when you adjust the top nut, put it slightly wider before tightening the lock nut, just as you did.

After the hard injector lines have been emptied, it can take a little longer to start, or the engine will start and stop soon. You can crack open the hard injector lines, but it is not really needed. After starting, run the engine at a fast idle so that the lift pump can pump all the air out of the system.

The spring should turn my means of the rotocap which is found underneath the spring. Everytime the valve opens and closes, the rotocaps turns the valve a bit, so that the valve and valve seat wear evenly. After many miles, the rotocaps can stop working, so that the valve doesn't rotate anymore. This can result in uneven wear of the valves and valve seats. If you turn the valve, for instance during valve adjustment, it can happen that the valve doesn't close anymore, because of the uneven wear. That is one of the reasons for using the third wrench.

Care to explain how the lift pump is capable of "pumping air" from the injector lines?

Sounds like you did not have the special of home bent Valve wrenches and to start off with did not remove the Fuel Injection Lines.

For the bottom nut you need to either thin out a wrench or find one that is thin. The special Hazet Valve Adjusting Wrenches have a thickness = 0.242; close to 1/4 of an inch 0.25".

Also the first time you do something can often be the worst and you started off without removing the Fuel Injection Lines.

It is hard to tell from your description if the Valve and Spring Retainer were rotating or not when you did your adjustment.
That happend to me on the first Valve Adjustment but I had that 3rd Wrench. However, in the threads there are several methonds of holding the Valve Spring Retainer to keep it from rotating.

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84 300D, 82 Volvo 244Gl Diesel

Sounds typical. There is clearance between the Threads of the Nuts and the Valve stem. Tightening up the lower Nut keeping the Upper Nut from moving pushes up the Upper Nut.

Holding the lower Nut and tightening the Upper Nut pulls the Upper Nut down.

The adjustment almost always changes a little after you tighten stuff up; it is that way on other Vehicles also.

Since in use the Valves tend to close up the clearence I don't think there is any harm if they are slightly on the loose side.

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84 300D, 82 Volvo 244Gl Diesel

Take a deep breath, and go over the valve adjustments again. It will take a little time, yes....but it will be easier than the first time you did it as you know what you are doing. Tighten the belt so turning over the engine will be easier. Crazy question, but you ARE making sure EACH cam lobe is set at the 1:00 position before you adjust the valve, correct??

I had a brother in law that did a valve adjustment and only set the cam so the first lobe was at the 1:00 position and then try to adjust all the valves, He thought you only had to have the first lobe at 1:00 and you could then adjust all the valves.

Try re-adjusting the valves, bleed the fuel lines and I'll bet it runs a lot better.

Good luck

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2012 Mercedes ML350 Bluetec 102K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 238K (mine)
1998 Volvo S70 T5 Turbo 211K (kids)
1994 Ford F150 4WD 246K (firewood hauler)
1983 Mercedes 300D 384K (diesel commuter)

The IP will do that, the lift pump will pump air out of the low-pressure area.