Oil consumption & a cloud of smoke on startup

[skyotee]

So the other day, I started up my E46 after it had been parked for only a couple of hours. On startup, a giant cloud of bluish white smoke billowed out the exhaust, and lingered in the air for a few seconds. No more smoke came out of the exhaust after that.

It seemed like it was smoke from burning oil to me (bluish, foul smelling, and lingered in the air for a long time). I have not been getting any DME codes, but I have noticed excessive oil consumption. I lost about a liter of oil in around 3,000 miles of driving. And I don't see any oil leaks or oil stains under the car where I park it.

Any ideas? I am thinking CCV problem, since the car is a 2006 with 140K on it, and never had the CCV replaced. But, I tested the crankcase vacuum by using a manometer at the oil dipstick tube and got 5.75" of WC at idle with a warm engine. Which seems to be within the BMW spec of 10 - 15 millibars, or 4" - 6" of WC.

Anything else I should consider or look into, besides CCV? Or since the CCV is really old, and I am near the max spec of vacuum, I should just replace it? Or should I just not worry about one cloud of smoke, that has never repeated since, and expect that kind of oil consumption on an old car?

[SloopJohnB]

Depends. If you've not had excessive oil consumption but alluvasudden you lose a liter in 3000 miles, yes, you likely have something fubar. Sounds like you should replace the CCV on GeneralPrinciples...It's not an easy job notwithstanding a video on how to do it....
https://www.youtube.com/watch?v=tMwVe0NAcZs

I would suggest getting OEM BMW parts (probably only ones available anyway) from FCP Euro...they have a lifetime warranty.

[Durlaker]

Blue/Gray Smoke: Blue/gray exhaust smoke is an indication of oil burning in the combustion chamber. These are possible symptoms and causes:

Valve Seals: Leaking valve seals will cause blue/gray exhaust smoke.

Valve Guides: Excessive clearance between the valve stem and the valve guide allows oil to leak past the gap into the cylinder.

Piston Rings: Worn or damaged piston rings will cause blow-by, resulting in blue/gray smoke.

Worn Cylinder Walls: Worn cylinder walls cause blow-by, resulting in blue/gray smoke.

PCV System: A stuck closed PCV valve causes excessive crankcase pressure, resulting in blue/gray smoke.

http://www.freeasestudyguides.com/exhaust-color.html


While I'm no mechanic, this is the extent to what I've heard about, figured I'd try and find a half-way decent source on it.

Good Luck, hopefully other members can be more precise!

[nonturbodan]

Rings may be sticking. I would try Rotella T6 on your next oil change, see if it improves the consumption. It has worked for me in the past on the M54.

[MarcoZandrini]

If this happened all of a sudden then I’m betting the old CCV is bad. Btw, an M54 burning a quart of oil every 3000 miles is week within BMW specs.

[jclausen]

I burn about 1 qt in 3500 miles my cvv is new I have 144k on the engine

[hbennett76]

Typically, if you are burning oil at startup, I would suspect valve stem seals or guides. If worn, oil will seep by these into the combustion chamber and burn off out the exhaust on startup. I'm not sure about everyones oil consumption but mine doesn't. I know someone who had a good running '02 325i that used a motorflush in it and it started burning oil like the other posters experience. What had happened was some of the old sludge was freed and clogged the oil rings on the pistons, forcing oil into the combustion chamber. A ring job remedied the oil consumption.... OK, it was me. My current is an '04 330Ci. It doesn't use any oil either.