Preface: I know there are several threads on this. But I wanted to post a video to get some more specific input.

For the past year or so, my wagon has had exhibited rough starts when cold. Missing several times, plus clouds of white smoke are the norm, especially when cold (under ~ 50 F). In addition, the 617 often misses when hot. I can't figure out the rhyme or reason for this. Sometimes when hot, it idles nice and smoothly at a red light. Other times when hot, it will miss every 3-5 seconds at idle.

Recently, this problem has gotten worse. After I replaced 2 bad glow plugs, the rough start and associated white smoke seems to have gotten worse. I have verified the functionality of the GPs several times -- testing the wiring, and the glow plugs themselves. I even removed the newly replaced GPs and tested them outside the car, just to make sure that they were glowing nice a hot. I am not sure why the rough start + smoke has gotten worse after replacing bad GPs. One would assume that GPs would alleviate problematic cold starts!

I should note that the 617 is about due for a valve adjustment. I know that this should help the smoking issue. But I don't think it would help the missing. In addition, like I said, this problem seems to have gotten about 2X worse immediately after replacing GPs.

In the video, you should be able to hear some rough starting on first crank. To me it sounds like the motor isn't firing on all cylinders. Then, in addition to the white smoke, a few puffs of black smoke will shoot out of the tailpipe. These are associated with the miss. Eventually the black smoke goes away, but the white smoke continues to be expelled for some time.

My current hypothesis is that there's an air leak. I am not sure how to further troubleshoot or fix that. I tightened the connections at the fuel filters, and I have the new-style primer pump. Should I replace all the rubber lines in the engine compartment? Time for new braided return hoses?

Any input is appreciated.

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-1985 300TD - 324k mi on chassis. MB "Tauschaggregat" 617 motor + 4-speed conversion
Alaska Roadtrip 2009
-2002 E320 Wagon - 197k mi
-1998 E320 Wagon - 310k mi - retired