BMW 420i burning oil at start up

[gkl106]

I have a BMW 420i that emits blue smoke from the exhaust for a couple of seconds after start up, after that it is absolutely clear, the longer the car is left the more smoke blows out. Does anyone know a BMW specialist that can fix this problem.
Cheers

[d_a_n1979]

gkl106 said:

I have a BMW 420i that emits blue smoke from the exhaust for a couple of seconds after start up, after that it is absolutely clear, the longer the car is left the more smoke blows out. Does anyone know a BMW specialist that can fix this problem.
Cheers

What's your location?

Is the car under warranty at all?

Does the 420i have a PCV / CCV system do you know, if not Google this as it could be a DIY fix?

I think it's unlikely as to be anything like valve stem oil seals; but worth checking on Google to see what other owners have said etc

[Aluminati]

Valve guides/seals.

[E-bmw]

Try slowing down from motorway speed using just engine braking, does it do it then also?

If yes that makes valve guide seals more likely, but either that or PCV as above.

[GreatStuff]

I have the same engine in a 5 series touring and it has done exactly the same for a good few years. My oil consumption is still very low at 108k miles, hence I have stopped worrying about it

[Magnum 475]

I mentioned this in your original thread, these engines are also prone to turbo oil seal failure. This was my 330i on cold start with 45k miles on the clock, and after the BMW dealer had replaced the PCV system as that's their cheapest option for a fix:



It would clear after a few hundred metres of driving, but produced a proper fog bank the first time you opened the throttle.

Is yours the B48 engine?

Edited by Magnum 475 on Tuesday 2nd August 09:03

[GreatStuff]

I have the same engine in a 5 series touring and it has done exactly the same for a good few years. My oil consumption is still very low at 108k miles, hence I have stopped worrying about it

[gkl106]

[quote=Magnum 475]I mentioned this in your original thread, these engines are also prone to turbo oil seal failure. This was my 330i on cold start with 45k miles on the clock, and after the BMW dealer had replaced the PCV system as that's their cheapest option for a fix:



It would clear after a few hundred metres of driving, but produced a proper fog bank the first time you opened the throttle.

Is yours the B48 engine?

Edited by Magnum 475 on Tuesday 2nd August 09:03

[/quote

No mine is the n20 engine and it only smokes for 3 or 4 seconds at most, and doesn’t use oil🤔

[Magnum 475]

Time to get it booked in for someone to look at then. Hopefully it'll be an easy fix, like the PCV system. But without someone physically examining it, it's impossible to identify the source. Based on my experience with a BMW main dealer, even they don't always get the diagnosis right first time.