1980 300sd Turbodiesel. I did the adjustment twice after hearing clattering the first time. I double and triple checked for proper clearance, order of intake/exhaust and ensured the locking nut was tight. I cranked it over with a remote starter (IP and glow plugs disabled) and the rocker arms seems to be moving fine and I can see the valves through the springs so I did not drop one. I covered it all back up, connected the glow plug relay and released the stop to the IP. Started the engine with the injector that I had to disconnect partly cracked to bleed any air. Again, I heard a very loud banging sound and quickly shut it off. I should note that the chain looks fine but I did not check for tension or timing as I don't quite know how to do this yet. Thoughts?

did you over tighten the valve cover nuts and lower the cover too far? or not replace that gasket and it is smaller than it should be? they get pretty close normally.

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1983 240d 5Sp SOLD
1986 300D(LUCO) SOLD
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No, I tightened to spec (15NM i think) with a torque wrench and used a new gasket that looks perfectly seated.

I'm guessing you had to disconnect one of the hard fuel lines to get your wrench in there for the adjustment. Right? So, you got some air in the line. Then you left it cracked to bleed the air, which is fine, but realize that it is going to run pretty rough and sound pretty bad with any air in the line and while the line is cracked. You said you shut it down immediately. It might just be a case of needing to work the air out of the line - you'd be amazed at the sound the engine will make if one cylinder in not getting adequate fuel/air mixture. If you've double checked the intake/exhaust order and the clearances are good, I would do as you've already done, try to bleed out any air from that line, then tighten it up and let it run for minute to see if it smoothes out.

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'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
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"Back off, man. I’m a scientist” ~ Peter Venkman

did you do it cold or warm engine?

and what do you mean by "disabled IP" ?

.

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Tankowner, I am tempted to take your advice, but if there is a bent valve or something would that one minute further complicate the problem?

cho, I meant that I clamped the linkage that attaches to the "stop" lever in the stopped position to cut off the fuel.

I understand. By all means, don't proceed until you are comfortable that you are not doing more harm than good. Was the problem present prior to your valve adjustments?

You originally mentioned hearing "clattering the first time" but then also mentioned the hard knocking . . . are those the same thing. Meaning, did you do the valve adjustment to try and remedy the hard knocking, or did the hard knocking originate following your adjustment?

__________________
'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
______________________________________

"Back off, man. I’m a scientist” ~ Peter Venkman

Did you leave a wrench where the fan can hit it?

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2004 F150 4.6L -My Daily
2007 Volvo XC70 -Wife's Daily
1998 Ford F150 -Rear ended
1989 J-spec 420SEL -passed onto its new keeper
1982 BMW 733i -fixed and traded for the 420SEL
2003 Volvo V70 5 Speed -scrapped
1997 E290 Turbo Diesel Wagon -traded for above
1992 BMW 525i -traded in
1990 Silver 300TE -hated the M103
1985 Grey 380SE Diesel Conversion, 2.47 rear end, ABS -Sold, really should have kept this one
1979 Silver 300D "The Silver Slug" -Sold

I did the valve adjustment as an overdue maintenance measure, but the car was running fine. The clatter was after the first adjustment, after a 1 mile test run that went fine. The next day I heard this clatter and when I got it on the ramps the clatter developed into more of a full on pounding sound.

It would be nice to get a video if the noise it is making, it may help with a diagnosis. Though it sounds like something wasn't done right, wrench left somewhere....damaged something using the crank pulley bolt....didn't measure the valve clearance in the right location...possible over due for an oil change? Possibly there is a lot of carbon buildup? Maybe something was damaged by clamping the IP in the stop position and using the remote start? Usually when I do a valve adjustment, I put the car in neutral and use the power steering bolt to turn the engine...

Good tutorial here

Mercedes Diesel Valve Adjustment Procedure

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Check your fan shroud. If you were leaning over the front, it may have pushed down and the fan blades are hitting the shroud. (Don't ask me how I know this.) It also creates a "knocking" sound that freaks you out momentarily.

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Sam

84 300SD 350K+ miles ( Blue Belle )

After 2 weeks of being out of town I returned home with a little more nerve to take this on by starting the engine again. I had gone over my process in my head again and again. I was confident that I did the job right and reassembled without dropping anything in.

I used the remote starter and started it up. The noise started and stopped. Started again. I grabbed my 17mm wrench and loosened the #3 fuel injector that I had messed with before. The noise got quieter but as I loosened it it got louder! Well, I'll be damned. It WAS the injection. Clearly I had not bled it enough to begin with. I tightened it just enough for it to weep fuel and ran it for a few minutes as the noise slowly died down. I still think I have some air in the system because I have more "nailing" than before I did the valve adjustment, but I am planning on rebuilding them soon anyway. I may just crack all 5 to see if I can further bleed the air.

I just cannot believe how loud an over loose injector and the air it traps can be. Tankowner, you were absolutely right. It literally sounded like the incredible hulk was pounding the inside of the valve cover. Lesson learned for the diesel Newbie. Still, I don't regret my overly cautious approach.

Glad to hear it Andy! I was just wondering today how you were doing. Hadn't seen any update on the W116 forum. Happy you got it figured out!
Matt