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I occasionally experience an oil smell coming through the cabin ventilation system. It is worse in winter months when the heater is running and (seems to be) nonexistent in summer with AC running. I tried to isolate the problem by completely shutting off the center console vents, thinking that the source of the smell might be coming from the engine bay and transmitting through the cabin air filters. This was based on the assumption that the center console vents always bring in outside air through those filters (I might be wrong on this). To no avail, the smell still occurs. This is not a continuous smell either, it seems to be triggered by brief idle periods after a loaded condition. Such as; if I were to be doing normal driving and then come to a stop.

Anyone experience this? Any solutions?

Some thoughts I had on this:

- If the oil smell is coming through the air cabin filter?
- Do I have a boost leak, where crankcase air is leaking into the engine cabin?
- How is the engine bay and cabin ventilation system connected other than the cabin air filter?
- Is what I smell actually melting plastic? whereas; the catalyst heat rejection is melting the HVAC duct work?
 

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'17 X1 - Rooster Cruisin'
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Any noticeable oil leakage from gaskets (above & below) in the engine compartment?
 

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How many miles & what engine? Typically, it's due to oil leaking from valve cover & dripping on exhaust. Once the "drop of oil" burns off, smell goes away.

Sent from my SM-G930R4 using Bimmerfest mobile app
 

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Discussion Starter #5
How many miles & what engine? Typically, it's due to oil leaking from valve cover & dripping on exhaust. Once the "drop of oil" burns off, smell goes away.

Sent from my SM-G930R4 using Bimmerfest mobile app
I do not doubt your suggestion. However, I am a little conflicted with how these two things are connected though. This would suggest that the cabin intake air system is connected to the engine bay. So the oil burns off and then gets circulated into the engine cabin filter intake box.. I struggle with this scenario because the cabin intake air comes through the louvered passages at the base of the front window on the outside of the vehicle, totally separated from the engine bay. I guess it is possible that air from the engine bay can seep out through the seal and get into cabin air filter box. But if I am confident that my cabin intake air box is sealed well, then I should not expect to get any engine bay air in.

Have you proven this out?
 

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- The top engine bay separation panels are known to crack over time, providing a passage straight into the air intake area

- when at standstill, the outside route from front grille to air intake is well possible. You can expect to see smoke for a few seconds in such cases, but you do not report that.




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I do not doubt your suggestion. However, I am a little conflicted with how these two things are connected though. This would suggest that the cabin intake air system is connected to the engine bay. So the oil burns off and then gets circulated into the engine cabin filter intake box.. I struggle with this scenario because the cabin intake air comes through the louvered passages at the base of the front window on the outside of the vehicle, totally separated from the engine bay. I guess it is possible that air from the engine bay can seep out through the seal and get into cabin air filter box. But if I am confident that my cabin intake air box is sealed well, then I should not expect to get any engine bay air in.

Have you proven this out?
No...haven't proven it. Just experience from owning BMW's from 1996. Take it to your preferred BMW mechanic and explain to them what you have posted.

Good luck with it.
 

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Resident Curmudgeon
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"oil smell"

Ive never really notices a smell from oil.

;)

burn the oil, then yes it smells


OP there is a LONG history of noxious smells from the engine compartment getting into the cabin intakes. Search for EGR cooler failurwes in the diesels. Yes, it is a diesel, but the 'problem' you seem to be having is how air gets into the cabin: it happens, your cabin air system is the same as all other engines
 

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CALS
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I occasionally experience an oil smell coming through the cabin ventilation system. It is worse in winter months when the heater is running and (seems to be) nonexistent in summer with AC running. I tried to isolate the problem by completely shutting off the center console vents, thinking that the source of the smell might be coming from the engine bay and transmitting through the cabin air filters. This was based on the assumption that the center console vents always bring in outside air through those filters (I might be wrong on this). To no avail, the smell still occurs. This is not a continuous smell either, it seems to be triggered by brief idle periods after a loaded condition. Such as; if I were to be doing normal driving and then come to a stop.

Anyone experience this? Any solutions?

Some thoughts I had on this:

- If the oil smell is coming through the air cabin filter?
- Do I have a boost leak, where crankcase air is leaking into the engine cabin?
- How is the engine bay and cabin ventilation system connected other than the cabin air filter?
- Is what I smell actually melting plastic? whereas; the catalyst heat rejection is melting the HVAC duct work?

Had the same issue (Oil Smell) and experienced the same behaviour ("worst" in Winter)

I found a Valve Cover Gasket Leak (at the rear of the engine, close to the O2 Sensor) AND and an Oil Filter Housing Leak (this leak went through the side of the engine, below the intake manifold)

The Cabin Air Intake for the E70 is on the right side (passenger side) just above a plastic partition that is prone to break or get misaligned, which will allow gases/burnt oil smell from the VCG Leak to go from the engine into the cabin.

You will likely feel it *more* in winter as you will likely drive with the windows up most of the time.

Check for oil leaks in the very back of the engine
 

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CALS
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- The top engine bay separation panels are known to crack over time, providing a passage straight into the air intake area

- when at standstill, the outside route from front grille to air intake is well possible. You can expect to see smoke for a few seconds in such cases, but you do not report that.




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+1 - this is how the smell/vapours go inside

I had to replace these AND the gasket that goes across the partitions
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 99K miles NOKIAN WR G3 12K miles
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Anyone experience this? Any solutions?
This is precisely the circumstance that the AUC is intended to prevent.

***8220;Sensor for automatic air recirculation control

> E8x, E9x only IHKA

> E7x (only integrated automatic heating and air-conditioning system in High version)

The AUC sensor is fitted on the microfilter compartment. The AUC sensor detects the following pollutant emissions from spark-ignition and diesel engines:

Hydrocarbons (CH )
carbon monoxide (CO)
Nitrogen oxides (nitrogen monoxide NO, nitrogen dioxide NO2)

The junction box supplies the AUC sensor with voltage. The junction box electronics evaluate the data of the AUC sensor. The junction box electronics unit transmits relevant data to the IHKA control panel (via the K-CAN).***8221;
 

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in my case it was cracked crankcase vent pipe (brittle plastic tube known to crack over time), the oil smell usually occurred after the oil inside the engine reached its working temperature. there are two of them and two connecting tubes, all of them were replaced during CCP but lasted only 3 years. So after replacing the cracked vent pipes the smell disappeared.
 

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Resident Curmudgeon
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This is precisely the circumstance that the AUC is intended to prevent.

"Sensor for automatic air recirculation control

> E8x, E9x only IHKA

> E7x (only integrated automatic heating and air-conditioning system in High version)

The AUC sensor is fitted on the microfilter compartment. The AUC sensor detects the following pollutant emissions from spark-ignition and diesel engines:

Hydrocarbons (CH )
carbon monoxide (CO)
Nitrogen oxides (nitrogen monoxide NO, nitrogen dioxide NO2)

The junction box supplies the AUC sensor with voltage. The junction box electronics evaluate the data of the AUC sensor. The junction box electronics unit transmits relevant data to the IHKA control panel (via the K-CAN)."
Datasheet on the sensor inside:

http://www.figarosensor.com/products/822pdf.pdf


https://forum.e46fanatics.com/showthread.php?t=884216

IMO it doesnt seem to be anywhere NEAR as sensitive as my nose!
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 99K miles NOKIAN WR G3 12K miles
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17,461 Posts
Interesting information. Thank you again.
 

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CALS
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This is precisely the circumstance that the AUC is intended to prevent.

"Sensor for automatic air recirculation control

> E8x, E9x only IHKA

> E7x (only integrated automatic heating and air-conditioning system in High version)

The AUC sensor is fitted on the microfilter compartment. The AUC sensor detects the following pollutant emissions from spark-ignition and diesel engines:

Hydrocarbons (CH )
carbon monoxide (CO)
Nitrogen oxides (nitrogen monoxide NO, nitrogen dioxide NO2)

The junction box supplies the AUC sensor with voltage. The junction box electronics evaluate the data of the AUC sensor. The junction box electronics unit transmits relevant data to the IHKA control panel (via the K-CAN)."

Yes, it is supposed to close the outside air intake, however, I believe it gets overridden when the Front Defroster gets chosen --This is also why, the smell *seems* to happen more in Winter, precisely when defroster is needed-- at least that was my theory. At the end, the key is to get to the root cause which was the VCG leak (for me)

Thx
 

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BMW CCA 69606
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The '11 might be different, but the AUC sensor on my '08 is only activated if the "A" light on the recirc button is lit.
Running the IHKA in "Auto", doesn't automatically engage the AUC function, it must be manually selected.
 

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I have that same smell, 2011 X5 Diesel. I only notice it when I slow down , especially after driving on interstate and coming down the exit ramp. The Service center said there was a small leak on the engine, but I have not been able to find it myself. No oil on the floor.
 

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I do not doubt your suggestion. However, I am a little conflicted with how these two things are connected though. This would suggest that the cabin intake air system is connected to the engine bay. So the oil burns off and then gets circulated into the engine cabin filter intake box.. I struggle with this scenario because the cabin intake air comes through the louvered passages at the base of the front window on the outside of the vehicle, totally separated from the engine bay. I guess it is possible that air from the engine bay can seep out through the seal and get into cabin air filter box. But if I am confident that my cabin intake air box is sealed well, then I should not expect to get any engine bay air in.

Have you proven this out?
The smell of burning oil is evidence of an oil leak in itself. Most likely coming from the valve cover gasket and dripping onto the exhaust. The assumption that the air venting is sealed from the engine bay is wrong for two reasons. First. It depends on your heater vent settings and whether or not you have it set to recirculate which recirculates the air inside the vehicle and doesn't take in outside air. Second. The air venting system is not hermetically sealed from the engine bay. The amount of smoke from oil burning on the exhaust will work its way into the venting system. You may not be able to see the dripping oil if it is at the back of the engine unless you use a mechanics mirror and a flash light. The only way to stop the smoke working it's way into the cab is to fix the oil leak permanently.
 

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CALS
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+ 1

@ Ahmadahere - the outside air gets into the cabin through the bottom portion of the air filter assembly - there is a plastic partition just underneath and around it, which is known to crack with age plus the upper portion seal can get dislodged creating a gap as well; if there is oil dripping on the exhaust manifold, it can get sucked in to he cabin this way, specially when a stand still. See the picture below - the seal is moved from its position, the partition below is the one that cracks.....

 

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I have that same smell, 2011 X5 Diesel. I only notice it when I slow down , especially after driving on interstate and coming down the exit ramp. The Service center said there was a small leak on the engine, but I have not been able to find it myself. No oil on the floor.
'service center'?

Diesels can get an EGR leak, which results in DIESEL fumes into the cabin.

You have 'the same smell'??? (How does one define smells on a typed forum???)

Burning oil? or diesel exhaust?

Two different beasts, different motors..... your 'oil leak' per the service center may be unrelated to the occasional diesel exhaust whiff.
 
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