Exhaust smoke on startup

M6pete · 02-02-2024, 08:19 PM

First startup in the morning I have cloud of blue/grey smoke from the exhaust. Anybody else had this? Thanks.

Billfitz · 02-02-2024, 10:43 PM

It happens all the time. Somewhere oil is making its way into the combustion chambers. The injector oil lines are one source.

fijigabe0 · 02-06-2024, 08:06 AM

How many miles on the engine? As Billfitz said, oil is making its way into the combustion chamber. If you have a high mileage engine, it could be worn valve seals (a problem that plagued the N62 engine, but not sure about BMW I4's or I6's), but I'm just guessing at this point. I would take it to a reputable shop to diagnose.

danielngan · 02-08-2024, 07:44 AM

N20 engine?

Burnout · 02-08-2024, 11:26 AM

My N55 engined car does the same. I realize you may have a different engine but their architecture is similar.

I suggest starting by removing the intake pipe and seeing if you have signs of oil entering the intake from the PCV breather hose. If so, then you’d be looking at Valve Cover replacement.

If that’s eliminated you’re looking downstream, so next stop cylinders as noted by Billfitz.

Another possibility is the turbo seals. Searching the forum will get hits in threads on this subject.

For me I’m inclined to look at turbo seals now that I’ve replaced the VC, added a catch can, and still have smoke on startup and other situations at idle like drive thru’s. The N straight six engines don’t have much documented history of valve stem or head gasket issues, but there is more cases of turbo seals leaking.

02-02-2024, 08:19 PM	#1
M6pete Registered 0 Rep 1 Posts Drives: F31 328i Join Date: Feb 2024 Location: Cambridge, NZ iTrader: (0)	Exhaust smoke on startup First startup in the morning I have cloud of blue/grey smoke from the exhaust. Anybody else had this? Thanks.
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02-02-2024, 10:43 PM	#2
Billfitz Lieutenant General 8245 Rep 16,085 Posts Drives: '15 328iX GT Join Date: Jan 2015 Location: New Hampshire iTrader: (0)	It happens all the time. Somewhere oil is making its way into the combustion chambers. The injector oil lines are one source.
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02-06-2024, 08:06 AM	#3
fijigabe0 Second Lieutenant 20 Rep 220 Posts Drives: 2013 F30 335i M Sport Join Date: Feb 2007 Location: Texas iTrader: (0)	How many miles on the engine? As Billfitz said, oil is making its way into the combustion chamber. If you have a high mileage engine, it could be worn valve seals (a problem that plagued the N62 engine, but not sure about BMW I4's or I6's), but I'm just guessing at this point. I would take it to a reputable shop to diagnose. __________________ Gabe '13 335i M-Sport Past - '06 330xi, '07 X3 3.0si, '09 328i, '12 X3 XDrive 35i
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02-08-2024, 07:44 AM	#4
danielngan Registered 0 Rep 1 Posts Drives: F35 320Li Join Date: Feb 2024 Location: China iTrader: (0)	N20 engine?
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02-08-2024, 11:26 AM	#5
Burnout Enlisted Member 27 Rep 43 Posts Drives: previously an E39 528i, now an Join Date: Jul 2013 Location: NS iTrader: (0) Garage List 2014 F30 335xi [0.00]	My N55 engined car does the same. I realize you may have a different engine but their architecture is similar. I suggest starting by removing the intake pipe and seeing if you have signs of oil entering the intake from the PCV breather hose. If so, then you’d be looking at Valve Cover replacement. If that’s eliminated you’re looking downstream, so next stop cylinders as noted by Billfitz. Another possibility is the turbo seals. Searching the forum will get hits in threads on this subject. For me I’m inclined to look at turbo seals now that I’ve replaced the VC, added a catch can, and still have smoke on startup and other situations at idle like drive thru’s. The N straight six engines don’t have much documented history of valve stem or head gasket issues, but there is more cases of turbo seals leaking.
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