how much black smoke is normal at cold start? - PeachParts Mercedes-Benz Forum

JHZR2 · #1 05-17-2010, 10:54 AM

Had my wife start up my 82 300CD yesterday, she is well trained to let it glow fully before starting. Got a little poof of black smoke coming out.

Also saw my car being started without being glowed when on the alignment rack (warm), a little more but still minor poof.

Should there be any poof of black at all? I havent checked my glow plugs, but could this be indicative of one prechamber not getting hot enough?

I know that at cold start, I often have a FTF because I hold it just long enough for it to sound like it catches, but then it doesnt. Hold it a tad longer and it is fine, or do it a second time and it starts quick. Never takes more than four cylinders to fire though - so I think it is user error...

But I want to optimize. If this poof is indicative of an injector issue or something else, I want to fix it. I honestly do not recall a small black poof coming from any of my other w123s.

Thanks

vstech · #2 05-17-2010, 11:05 AM

none of mine poof black smoke at startup... now under a load... maaaybe...

JHZR2 · #3 05-17-2010, 12:41 PM

right. And a poof isnt even a good explanation, more of a tiny little cloud, not even 1 ft in diameter coming out at initial start. just see it immediately after the engine catches, and within a second or two it has dispersed.

But it means I need to check glow system and injectors, right?

Surely this could be related to my indy mentioning that I have a leaking injector...

Thanks for your help, just want to make my car 110% right...

Joseph_Conrad · #4 05-17-2010, 12:53 PM

Does your car let off the smoke cloud every time it's started when cold? Does it seem to matter how long the car's been sitting for?

My car lets off a similar poof every once in awhile, but mine seems somewhat inconsistent.

DieselPaul · #5 05-17-2010, 12:56 PM

If my 603 sits for a week or so it'll smoke pretty good for the first few seconds then shes all good.

JHZR2 · #6 05-17-2010, 01:15 PM

I've only noticed it recently, never have really been looking though. Even fully cold it is only a tiny poof for a split second if glowed normally...

bustedbenz · #7 05-17-2010, 02:31 PM

Both of mine smoke on cold start and then clear up. I consider it normal.

DieselPaul · #8 05-17-2010, 03:07 PM

People who say their diesels have never smoked ever under any circumstance bought gassers.

A lil smoke has always been the norm in my book.

Oldwolf · #9 05-17-2010, 03:13 PM

Mine will give a black poof when starting sometimes. I haven't correlated why it does sometimes and why it does not sometimes though.

cirrusman · #10 05-17-2010, 03:19 PM

Mine poofs a bit of blueish smoke when cold and goes away when it's warm. I wouldn't worry. Unless you start hearing noises or feeling odd vibrations...