Perhaps some of you can help me identify what this noise could be.

1) When I start the car on cold morning, it sounds like there are a bunch of loose bolts and nuts bouncing around the engine,...lasts about 5-7 minutes until engine is warm. (valve adjustment needed? or injector ping?)

2) Engine warm or cold, if I rev to about 1200 rpms, I get a loud knock. Not evident any other time, only at 1200. Car idles at around 5-6k rpms.
(valve adjustment needed? or injector ping?)

Thanks
cchkaiban

1.) Somewhat common, goes away if you have the after-glow glowplug system as it helps it run smoother. Its usually from having old injectors. Most of these diesels are clacky/cranky when started in the real cold temps.

2.) Sounds like an injector knock or nailing....probably a bad injector nozzle....

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'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Hopefully you meant that it idles at 500-600rpm and not 5000-6000rpm. I believe specs are 750-800rpm or possibly 700-800rpm. Probably could stand to be adjusted up a little bit, especially with winter approaching.

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1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150

Agreed, unless the idle is not a problem in cold weather.

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83 SD

84 CD

Try running some Lubro-Moly diesel purge thru the injectors.
If they are dirty, this will clean them and lessen the nailing.

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
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85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles

Actually...yes around 700.... And it idles just fine. Just sounds terrible in the am.
Is there anyway to identify a bad injector(s)? Engine does struggle when I crack the lines one at a time.
Thanks..

now it's 700,000Rpm?

it can't possibly be any RPM in the "thousands" range for idle, the engine would runaway and blow up so fast....70 + x10 = 700

And it physically can't rev above 5200RPM that's with your wheels off the ground and you foot to the floor. take a photo of the tach at idle.

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Well that made me look like an idiot...Not sure why I put thousand?? I know what it idles at and I can...do some simple math

Anyway...are the only ways to pinpoint a bad injector to pop-test it or cracking it open while the engine is running?

Thanks

They are the most effective, DIY ways. Cracking the lines generally will tell you wether it is an injector or not. Crack each one, and note whether it affects the performance of the engine (missing, etc.). When you crack one and it changes nothing, there's your problem. It may be more than one, though...

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1989 300E 144K

You might be able to see if one has less effect on the engine than the others when you crack it, otherwise your best bet would be to pull them and have them checked, be sure to replace those heat shield discs if you pull them. I think I have a weak one, but it holds its own good enough once warmed up, so for now I'm letting it be until I get ready to swap the engine over to the 82.

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Chris
64 190D R.I.P.
80 240D W/617 engine -for sale
82 240D -for sale

Also I'd look at your air cleaner mounts and your motor mounts. when it's cold everything's stiff and loosens up when it warms up

another one is it could be some piston slap which = rebuild...a sound clip sure would help..

how cold does it have to be before it won't start without plugging in? could have a dead glowplug. I had one dead one and it made a hell of a racket till it got hotter..

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RIP: 80 300SD
RIP: 79 450SEL
2002 E430 4matic (212,000km)
2002 ML500 'sport'

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