Smells like burning...

costasbrehm · 11-15-2015, 02:35 PM

Hello,

Recently I've noticed a burning smell coming from under the hood of my stock 2012 328i (52,000 miles). I first noticed it after a spirited drive to work last week, in which I ran it up after a stop signs on a back road (5500+ rpm). The smell was so strong that I noticed it immediately after opening my door when I arrived at work. Since then I've checked under the hood after every drive to and from work, and the smell seems to be coming from one particular tube (highlighted in the picture below). It's been 8 months and 5,000 miles since my last service, and the oil level still says 100%, but the coolant is slightly low. I can't say if the coolant was serviced appropriately by the dealer last time, or if it's been slowly dropping, but I've yet to get the low coolant light. Here are a few other pieces of info that might be helpful based on other threads I've been reading:

--The smell is not noticeable inside the vehicle with the heat / AC on or off, only from outside.

--There is a small amount of smoke from the exhaust on start up after the car has been sitting for ~24 hours, but not nearly as bad as the videos people have posted indicating major problems with the turbo. The smoke dissipates within a few seconds after start up, but returns momentarily if you run up the RPMs.

--The belt appears to be in perfect condition, with no signs of rubbing or abnormal wear.

--There are no visible leaks anywhere under the hood.

--The smell seems to get stronger the harder I drive the car. On a normal commute (15 miles, most of it on cruise at 60mph), it's only noticeable if you pop the hood and lean in.

Any thoughts on what the specific problem might be, or further steps I can take to help diagnose it? Thanks,

Paul
(the attached picture is borrowed from another post; I've not yet taken to disassembling things...)

KGB_123_99 · 11-23-2015, 09:15 AM

Is it a sweet burning smell? After driving the car hard have a smell under the hood. If it smells sweet like burnt sugar, then it's coolant. In that case, look for white residue which is left when hot coolant dries. If you have a leak from the coolant pipe you circled, it'll be rather obvious.

If you have an oil leak at this mileage that is causing a burning smell, it could be the valve cover gasket. Look at the passenger-side of your engine above the exhaust manifold...there's a thin metallic plate that is supposed to prevent oil from hitting the hot exhaust if there is a leak. If you see oil accumulation on it, then that's your problem and a relatively inexpensive fix even at the dealer.

Aside from the turbo, there aren't any other things that can cause a burning smell under the hood. I'll let the turbo experts chime in on the turbo.

11-15-2015, 02:35 PM	#1
costasbrehm Registered 2 Rep 1 Posts Drives: 2012 328i Join Date: Nov 2015 Location: NM iTrader: (0)	Smells like burning... Hello, Recently I've noticed a burning smell coming from under the hood of my stock 2012 328i (52,000 miles). I first noticed it after a spirited drive to work last week, in which I ran it up after a stop signs on a back road (5500+ rpm). The smell was so strong that I noticed it immediately after opening my door when I arrived at work. Since then I've checked under the hood after every drive to and from work, and the smell seems to be coming from one particular tube (highlighted in the picture below). It's been 8 months and 5,000 miles since my last service, and the oil level still says 100%, but the coolant is slightly low. I can't say if the coolant was serviced appropriately by the dealer last time, or if it's been slowly dropping, but I've yet to get the low coolant light. Here are a few other pieces of info that might be helpful based on other threads I've been reading: --The smell is not noticeable inside the vehicle with the heat / AC on or off, only from outside. --There is a small amount of smoke from the exhaust on start up after the car has been sitting for ~24 hours, but not nearly as bad as the videos people have posted indicating major problems with the turbo. The smoke dissipates within a few seconds after start up, but returns momentarily if you run up the RPMs. --The belt appears to be in perfect condition, with no signs of rubbing or abnormal wear. --There are no visible leaks anywhere under the hood. --The smell seems to get stronger the harder I drive the car. On a normal commute (15 miles, most of it on cruise at 60mph), it's only noticeable if you pop the hood and lean in. Any thoughts on what the specific problem might be, or further steps I can take to help diagnose it? Thanks, Paul (the attached picture is borrowed from another post; I've not yet taken to disassembling things...) Attached Images
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11-23-2015, 09:15 AM	#2
KGB_123_99 Captain 404 Rep 962 Posts Drives: '17 330ix M-Sport, '09 528ix Join Date: Apr 2014 Location: Montreal, QC iTrader: (0)	Is it a sweet burning smell? After driving the car hard have a smell under the hood. If it smells sweet like burnt sugar, then it's coolant. In that case, look for white residue which is left when hot coolant dries. If you have a leak from the coolant pipe you circled, it'll be rather obvious. If you have an oil leak at this mileage that is causing a burning smell, it could be the valve cover gasket. Look at the passenger-side of your engine above the exhaust manifold...there's a thin metallic plate that is supposed to prevent oil from hitting the hot exhaust if there is a leak. If you see oil accumulation on it, then that's your problem and a relatively inexpensive fix even at the dealer. Aside from the turbo, there aren't any other things that can cause a burning smell under the hood. I'll let the turbo experts chime in on the turbo.
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