Occasional smell of exhaust in cabin: A/C off, Sunroof open

faz · 06-19-2017, 01:36 PM

Hi everyone,
I did some searches and came across some posts, but I think my question / situation is different than those that were covered in my search results.

I have a 2011 335D with about 65k miles on it that I have owned for the last few months. Working beautifully and carbon build up cleanup was done on it prior to my purchase by the local dealership under CPO.

I love everything about this car. Absolutely EVERYTHING!

The only thing that bothers me, is that I occasionally smell a faint smell of exhaust in the cabin. This is not the smell of diesel fuel, no. This is a smell of exhaust that might be finding its way through the a/c filter into the cabin. Let me explain:

- with windows up, a/c on, I *never* smell any fumes whatsoever. Beautiful as I expect and like all other gas bmw's I have owned. No issues whatsoever.

- The scenario that brings the smell in, is if I have the a/c off, but the fan running, trying to get the regular cool air from outside into the cabin through the fan. If i open the sunroof, whether tilted or wide open, I start to smell some fumes inside the car. I can't confidently say it is from vents/fan... and this smell is so faint that it is not bothersome to my wife and kids to make them mention it (I haven't mentioned it on purpose to see if it is something that one of them will also complain about, and never heard any complaints.)

- Seems to happen after having a little fun from red light to red light, WOT situations and enjoying the torque and higher rom runs (3-4 k, perhaps 5k, yes, not too high but more than the daily average commute scenarios.)

- again, if in this scenario I turn A/c on, and close the sunroof, no issues, no smell at all.

- after a hot afternoon ride I have actually stopped and raised the hood, tried to find anywhere that might have any leaks or smell of exhaust or ... nothing. all looks clean and well sealed.

Any ideas/opinions about this?? As mentioned above, I tried to search on this and didn't find anything that relates to my situation above, but if this has been discussed before, I apologize. Any links to existing threads about this would be appreciated.

rulonger · 06-19-2017, 05:57 PM

Check the horseshoe-shaped oil feed line on top of the turbos. I had a similar smell situation that I thought was exhaust or burnt oil. Seems that hose tends to seep and replacing it solved the smell issue.

See this thread: http://www.e90post.com/forums/showthread.php?t=1168839

torqueisking · 06-19-2017, 08:32 PM

Experienced this twice on my 35D but same should apply to the 335d.

First cause was a split EGR cooler toward the exhaust manifold within the "pleated" 90deg metal bend. It eventually blew wide open and the DDE went into limp-home mode.

Second cause due to loose bolts securing the turbo housing on the exhaust side. Write up on this 2nd cause here:

http://www.bimmerfest.com/forums/sho...d.php?t=889676

faz · 06-20-2017, 12:16 AM

Thank you both for your replies. Actually I had already come across both links in my searches and read through them. Looking at the engine bay around the areas that the links point out, no sign of fume leaks or dirt.

I will look into those again and check one more time.

Today I tried hard to reproduce the smell but couldn't.

If I could consistently reproduce it, it would make it a lot easier to pin point.

06-19-2017, 01:36 PM	#1
faz Second Lieutenant 21 Rep 287 Posts Drives: 2023 X5 x40i, 2018 330i F30 Join Date: Sep 2007 Location: Bay area, CA iTrader: (0)	Occasional smell of exhaust in cabin: A/C off, Sunroof open Hi everyone, I did some searches and came across some posts, but I think my question / situation is different than those that were covered in my search results. I have a 2011 335D with about 65k miles on it that I have owned for the last few months. Working beautifully and carbon build up cleanup was done on it prior to my purchase by the local dealership under CPO. I love everything about this car. Absolutely EVERYTHING! The only thing that bothers me, is that I occasionally smell a faint smell of exhaust in the cabin. This is not the smell of diesel fuel, no. This is a smell of exhaust that might be finding its way through the a/c filter into the cabin. Let me explain: - with windows up, a/c on, I never smell any fumes whatsoever. Beautiful as I expect and like all other gas bmw's I have owned. No issues whatsoever. - The scenario that brings the smell in, is if I have the a/c off, but the fan running, trying to get the regular cool air from outside into the cabin through the fan. If i open the sunroof, whether tilted or wide open, I start to smell some fumes inside the car. I can't confidently say it is from vents/fan... and this smell is so faint that it is not bothersome to my wife and kids to make them mention it (I haven't mentioned it on purpose to see if it is something that one of them will also complain about, and never heard any complaints.) - Seems to happen after having a little fun from red light to red light, WOT situations and enjoying the torque and higher rom runs (3-4 k, perhaps 5k, yes, not too high but more than the daily average commute scenarios.) - again, if in this scenario I turn A/c on, and close the sunroof, no issues, no smell at all. - after a hot afternoon ride I have actually stopped and raised the hood, tried to find anywhere that might have any leaks or smell of exhaust or ... nothing. all looks clean and well sealed. Any ideas/opinions about this?? As mentioned above, I tried to search on this and didn't find anything that relates to my situation above, but if this has been discussed before, I apologize. Any links to existing threads about this would be appreciated. __________________ -Faz 2023 X5 x40i M-Sport 2018 330i F30 (Previous: 2011 E90 335d , 2017 F15 X5 x35i , 2011 F10 535i 6spd, 2011 E70 X5 x35i, 2007 E90 328i, 2005 E53 X5 3.0i, )
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06-19-2017, 05:57 PM	#2
rulonger Lieutenant 111 Rep 529 Posts Drives: 2011 335d E90 & 2010 328i E91 Join Date: Feb 2015 Location: NC iTrader: (0)	Check the horseshoe-shaped oil feed line on top of the turbos. I had a similar smell situation that I thought was exhaust or burnt oil. Seems that hose tends to seep and replacing it solved the smell issue. See this thread: http://www.e90post.com/forums/showthread.php?t=1168839 __________________ 2011 335d Deep Sea Blue on Beige (stock except for the cheap ass wheels from PO) 2010 328i Tasman Green on Saddle (stock) Last edited by rulonger; 06-19-2017 at 05:58 PM.. Reason: link to thread
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06-19-2017, 08:32 PM	#3
torqueisking Private First Class 44 Rep 141 Posts Drives: 335D Sport Join Date: Mar 2013 Location: Toronto iTrader: (0)	Experienced this twice on my 35D but same should apply to the 335d. First cause was a split EGR cooler toward the exhaust manifold within the "pleated" 90deg metal bend. It eventually blew wide open and the DDE went into limp-home mode. Second cause due to loose bolts securing the turbo housing on the exhaust side. Write up on this 2nd cause here: http://www.bimmerfest.com/forums/sho...d.php?t=889676
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06-20-2017, 12:16 AM	#4
faz Second Lieutenant 21 Rep 287 Posts Drives: 2023 X5 x40i, 2018 330i F30 Join Date: Sep 2007 Location: Bay area, CA iTrader: (0)	Thank you both for your replies. Actually I had already come across both links in my searches and read through them. Looking at the engine bay around the areas that the links point out, no sign of fume leaks or dirt. I will look into those again and check one more time. Today I tried hard to reproduce the smell but couldn't. If I could consistently reproduce it, it would make it a lot easier to pin point.
	Appreciate 0 Quote