Black smoke on (very) cold start for 2011 323i - normal?

[crownbrick]

Hello all,

I'm looking at getting a 2011 BMW 323i in the near future, and looked at three today. They were between 40k and 50k km (25k and 31k miles). In Canada, the 323i has the 2.5L I6, which is an engine I'm unfamiliar with. All cars were great, though the motor did lack a bit of low-end grunt. However, I noticed that all three of them puffed black smoke for about 15 seconds after starting. Although it is -20C today (-4F) I was surprised to see this consistently happen with all three vehicles.

Is this a common thing on BMW engines? Is it something to be concerned about, or do they simply run super rich on cold starts? I was going to buy one of them today, but this is making me think twice.

Also, is a certain amount of oil consumption typical for low-mileage cars?

[Snayko]

N52 engines with 2.5 L are known for their unreliability. But not with 25k-31k miles I would say.
N52s with 3L are much better but still not very reliable.

About oil consumption: it depends on your driving style. If you driving like crazy (which I really doubt you can do with 323i) then be prepared to top off the oil every 1000-2000 miles.
But usually it consumes during long time(distance) journeys.
In my example (I have N52 3 liter) with 94k miles it eats 1 liter per 7000-10000.

About smoke - I've never observed black smoke from my car, but I live in Florida.
I would not recommend to buy such a car

[crownbrick]

Aren't the 2.5 and 3L engines nearly identical except for bore and stroke (and associated pistons, con rods, crank, cam etc.)? I hadn't read of any reliability issues except for the water pump problem.

I was surprised that all three cars (in two different places) did the same thing. It seems unlikely that they'd all have leaky injectors, so my other thought was that when it's that cold the fuel map pushes them to run pig rich on initial start. Any northerners care to comment? :)

[Mima]

The N52 is a pretty solid engine and lower cost to maintain compared to other modern BMW gems. Keep in mind we are still talking BMW "cost".

Regarding the smoke, I will pay attention next time I start my car in the cold. But I won't be surprised if I do. This may be traced to the common leaking valve cover gasket and I may have it also (not sure though since I do not have a complete repair history on the car).

[Snayko]

Aren't the 2.5 and 3L engines nearly identical except for bore and stroke (and associated pistons, con rods, crank, cam etc.)? I hadn't read of any reliability issues except for the water pump problem.

That's the point, that these engine have different manufacturers of pistons, rings. And I've heart many complaints about n52 b25, first sign is oil consumption : 1L per 1000-2000k means that engine needs to be rebuild.