I agree.

__________________
1993 W124 300D
-297K on the clock as I type this.

Hopping on board here... I just replaced my head gasket and am having somewhat similar symptoms. Mine lopes, smokes, and nails at cold idle, and just nails once warmed up. Above 1200rpm or so, it's smooth as silk, but back to idle, and the noisy nailing is right back.

I am wondering whether IP timing or air induction will cause the symptoms (given that they're only really evident at idle, and some only at cold idle). My car is also obviously missing when cold. If I start the car and try to drive it, I can feel it missing as I reverse... there is a distinct surge. That tells me it's cylinder-specific, but loosening the injector lines does not stop the nailing. Odd.

Must be the season for goofy OM602 fueling symptoms. I'll be keeping an eye on this thread.

OP -- any chance of an air leak in your fuel lines?

__________________
1992 300D 2.5T
1980 Euro 300D (sadly, sold)
1998 Jetta TDI, 132K "Rudy"
1974 Triumph TR6
1999 Saab 9-5 wagon (wife's)

I thought something was hinky about the Timing of your Rattle/Smoke starting.
AfterGlow is 60 Seconds Maximum.
[and your difficulty is beginning @ 15+ seconds]
(AND 32 Degrees "F" Engine surface temperature is certainly enough to kick in 48-52 seconds of AfterGlow .)
[32 "F" = 0 "C"] Chart below.

Now your trick is finding out why you are not getting your full AfterGlow.
(Or maybe NO AfterGlow at All!)

Test your B11/7 temp sensor first.(AND it's wire back to the GP relay)
Other Chart below are test criteria for Temp Sensor Testing (You'll need a DMM)

See the pictogram below:

Attached Thumbnails

     

__________________
'84 300SD sold
124.128

That's close enough to the chart's depiction of correct sequence.

Earlier you stated the difficulty started 10-15 seconds out from START.
(If that's still true ,I agree with you...No AfterGlow.)

If you're getting AfterGlow Properly
AND the engine is still Loud AND Smokey at Idle WITH THE ENGINE WARMED UP...
You've got other problems...as CSMC1 asked earlier Air Leak into Fuel System?

An Excerpt from your Original Post:
"Then it gets rough and plumes of white smoke come out the exhaust"

OverFueling = Black Smoke

I'm not gonna mention what "Blanco" or "Blanc" smoke means...
'cause I don't wanna put the Bad Mojo on your engine.

__________________
'84 300SD sold
124.128

For sure, it's 44-45 seconds on that video at roughly 29-32F engine/ambient temps.

However, the temperature was quite a bit warmer out when I said it started about 15 seconds after starting.

Based on that I am assuming that my temp sensor and afterglow system is working.

I just can't imagine a brand new car doing the same thing but I'v never owned a new MB diesel so that's speculation.

__________________
1993 W124 300D
-297K on the clock as I type this.

My understanding of what causes white smoke is diesel that's not burning.

As you can hopefully see in the video there is no visible smoke at start-up.

It only starts when the glow plugs shut off.

I do have some rough running conditions at idle when warm occasionally but that's usually when just barely warm and driving around town.

Yesterday I drove about 300 miles and I must say the engine was running like a sewing machine on the highway and at idle in between long highway stretches.

The only fuel line I haven't replaced is the one coming out the bottom of the fuel tank and I haven't noticed any fuel leaking there.

__________________
1993 W124 300D
-297K on the clock as I type this.

I also wanted to say that the engine actually starts up crisper when ice cold than it does when warm.

This could have something to do with the starter/battery when hot but it definitely is more impressive when cold.

Any ideas why that is?

__________________
1993 W124 300D
-297K on the clock as I type this.

Have you checked your compression?
Might want to review messages from cscmc1.
Black smoke = Fuel
White smoke = coolant

__________________
92 300D 2.5L OM602 OBK #59

(Actually ALL Starters on all engines.)

Oh! First X2 for BBDC's reply above (He used the Verboten Word I won't speak.
Three Things: 1.Verify that your afterglow is or is not working (Test Light)
2.An air leak does not also mean a fuel leak...These suckers will intake Air
and leave you clueless.3.Compression Test.

The Brush(s),there are 4 of them,wear and the brush dust coats the inside of
the Starter interfering with the cooling of the Starter.Also the dust provides
almost perfect media for a "Hot Soak",retention of engine heat.The Resistance
of the Windings in the Starter increases with the raised Heat levels,thus hampering the Starter's mechanical efforts at rotating the engine.

Depictions courtesy WAI.

Attached Thumbnails

   

__________________
'84 300SD sold
124.128

That may be true but I only have smoke when the engine is cold and after the glow plugs shut off.

I don't smoke at all once the engine is warmed up.

White smoke equals unburned diesel, too.

I have not checked compression but I zero blowby and it never gives me any grief starting.

When warm it takes a little longer(2 seconds tops) to start than then cold(almost instantaneously).

__________________
1993 W124 300D
-297K on the clock as I type this.

Is it possible to have zero blowby and still have compression issues?

__________________
1993 W124 300D
-297K on the clock as I type this.

Follow-up: in frustration, I removed my injectors jut to see if one might be incorrectly seated or something (and to check and see if any were oily or sooty, signaling a possible internal oil leak perhaps). While they were out, I thought I'd double-check glow plug operation. I had bench tested each, and my harness was delivering 12V, but I checked anyway, and lo and behold, #1 was not heating. I wiggled the harness at #1, and it lit right up. Funky connection, I guess. Anyway, I now *seem* to have (relatively) smokeless starts and smooth idle, although it's still nailing.

Moral of the story -- just because you have 12V at the harness connection and know-good plugs doesn't mean they're heating. I guess I lucked out. I'll try starting again tomorrow, in daylight if I get home in time, and report the results. Hope it stays as "smokeless" as my starts and short runs around the block tonight! I still need to sort out this nailing, though.

i-osprey: good luck with your diagnosis; keep us posted.

__________________
1992 300D 2.5T
1980 Euro 300D (sadly, sold)
1998 Jetta TDI, 132K "Rudy"
1974 Triumph TR6
1999 Saab 9-5 wagon (wife's)

If "Blowby" were as accurate a measurement of engine condition(Cylinder Walls,
Rings,Etc.) there would be a Gauge fitted to the Oil Fill Cap...
(Well ,No...There would be a Hazet tool consisting of an OFC with a pressure
gauge fitted [With a MB Part Number] costing $165.00 USD.)
AND Mercedes would mandate the use of that process INSTEAD of Compression
Testing.

Urban (SubUrban,Rural?) Mythology holds that bad "Sealing" increases "BlowBy".
[Kinda makes sense...That ESCAPING Compression Pressure has to go somewhere...
UNLESS the Head gasket is Broached in such a way to allow the Compression to force Coolant into the Combustion Chambers.]
[White Smoke,Poor Idle]

__________________
'84 300SD sold
124.128

The engine fired right up this morning with engine temps of 5F.

It started IMMEDIATELY and ran quieter than normal.

However, once the GP's are turned off the smoke and rough running comes back.

I doubt I have compression issues based on this.

I did one glow and I turned the key immediately after the glow light went off.

I don't think there's anything wrong with compression or my glow system.

__________________
1993 W124 300D
-297K on the clock as I type this.

How long before the engine stabilizes on its own?

I tend to think compression problem. Pre- and afterglowing masks it. I'd check compression on a cold engine at least to rule it out.

Sixto
87 300D