Sweet Smell from vents in BMW?

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I have a 2011 BMW 328i with a manual transmission that has an odd sweet sort smell that occurs intermittently. I smell it when the vents are on, more so with the heat, but also sometimes when the AC is enabled. It doesn't occur until the car has been driven for a bit, say 10 minutes or more. After that, it is there most of the time in the background but it is subtle, and builds up over time. I get a stronger whiff of it when I am going in and out of 1st or 2nd gear, particularly when starting out in 1st from a stop or after shifting into second to come out of a turn. Tight turns seem worse (i.e. a U-Turn). Sometimes I think I smell it when climbing a hill, but its not as consistent as when exiting a turn.

I have had the car looked at twice and we can't seem to figure it out. Because the smell is sweet, a coolant leak was suspected. The car had a leak at one point at the thermostat that was since fixed. It passes a pressure test now (I am told). Also I'm not sure the positional nature of the occurrence near/after turns or gear changes can be explained by such a leak. I would almost say its the clutch given when it occurs, but it smells rather sweet. Most clutches I have smell are much more "bitter". I also suspected a heater core leak, but there is no wetness on the carpet and no fog on the windows. I also don't seem to be losing coolant that I can tell.

Anyone have ideas on how to narrow this down? I'd like to get it fixed as the smell kind of gives me headaches and bothers my throat. Thanks
 
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Do a pressure test on the coolant system to see if the heater core is leaking. The headache is the normal I own a car headache
sick.gif
 
Thanks for the responses. Would you guys expect a car to pass a pressure test if their was a pinhole leak in the heater core? I wonder if the valve to the core is open or not when the car is off and the tester is hooked up. Also, would UV die show in the car interior if coolant is leaking and being sent through the vents as vapor in such a situation? I'm just trying to figure out a way to confirm before having to take the dash out to see...
 
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If you had Dexcool, that stuff is easy to spot. With a pinhole leak, it dries to an orange jell on the outside of the heater core fins.
 
Did the guy who hooked up pressure test had the vent dash system in the "correct" mode? Does BMW shut off coolant flow to interior when the car is off via solenoid? Did the guy who pressurize the system left it there for hours?

Occam's razor tells you what is the most likely cause even if you don't want to believe it.
 
Originally Posted By: GiveMeAVowel
The coolant leak does seem to make the most sense but the car is
only a 2011, how many miles on the car?




Bmw motors use junk gaskets. Common issue
 
Originally Posted By: Clevy
Originally Posted By: GiveMeAVowel
The coolant leak does seem to make the most sense but the car is
only a 2011, how many miles on the car?




Bmw motors use junk gaskets. Common issue


Common issue on parts that are in contact with oil (like the VCG's and the filter housing). The cooling system failures tend not to be gasket related, rather the plastic water pump will poop the bed or the plastic expansion tank cracks.
 
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