I believe there are some fancy instrument which can detect coolant traces, essentially a computerized nose! Not sure which shop would have it though. Your case might be worth using this and spend an hour of diagnosis time assuming you are getting the smell only inside the passenger cabin and not in the engine compartment. Taking off dash to get to the heater core on speculation is an extremely expensive proposal.
Sweet Smell from vents in BMW?
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could you try removing the blower motor and getting in there with a borescope? It sounds like a heater core to me. I don't know why the Germans made heatercore replacement require dash removal, my B5 Audis are like this and I dread the day I have to do it, it will probably have a for sale sign if that ever happens
I think the first piece of 528e going down the assembly line is the HVAC unit. It was the one area where my Grand Wagoneer was better.
I had a '98 BMW with the 2.5L straight six that had that same smell you describe. It up-chucked it's coolant three times in two years due to various plastic bits failing in the cooling system. So I never knew if it was residue from one of the failures, or if the heater core was also a problem. Then the head gasket blew. Never really got around to the heater core. Other failures in the cooling system did it in.
It's a shame to make such a great car with a TERRIBLE cooling system.
It's a shame to make such a great car with a TERRIBLE cooling system.
Its an e90 328i 2011 with 21k miles on it. I agree it doesn't seem likely that it would have a bad heater core due to age. But I mean the thermostat did already leak on it (which did show on the pressure test).
That and the fact that I get more a more intense whiff of the smell when starting out or doing a tight turn/maneuver. Its like it smells sweet, but when you'd expect to smell the clutch if it were going bad - but worse when the heat is on. The only thing I can think is turning or causing the car to jerk forward with a shift causes the leak to briefly get worse. So weird.
Would a breathalyzer pick up Ethylene Glycol? Its kind of sort of like alcohol right?
That and the fact that I get more a more intense whiff of the smell when starting out or doing a tight turn/maneuver. Its like it smells sweet, but when you'd expect to smell the clutch if it were going bad - but worse when the heat is on. The only thing I can think is turning or causing the car to jerk forward with a shift causes the leak to briefly get worse. So weird.
Would a breathalyzer pick up Ethylene Glycol? Its kind of sort of like alcohol right?
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Originally Posted By: Vikas
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.
What is the "correct" mode? I am not sure if they shut off flow to the interior if the car is off. I wondered because it seems that it takes 10 or so minutes for the heater to kick on when the car is started from cold. I don't know if thats because they don't send coolant to the core until the engine is up to temp, or just software telling the car its not worth turning on the fan until the engine is warm enough for you to feel it. The former would seem to be a complicated solution to a problem that doesn't really exist, but hey you never know with these cars.
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.
What is the "correct" mode? I am not sure if they shut off flow to the interior if the car is off. I wondered because it seems that it takes 10 or so minutes for the heater to kick on when the car is started from cold. I don't know if thats because they don't send coolant to the core until the engine is up to temp, or just software telling the car its not worth turning on the fan until the engine is warm enough for you to feel it. The former would seem to be a complicated solution to a problem that doesn't really exist, but hey you never know with these cars.
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How about bypassing the heater core by running a hose from supply pipe to the return pipe on the engine. If the smell goes away, you've nailed it.
Easier to do now than in the winter!
Easier to do now than in the winter!
+1 seems to be the best and easiest of the ideas.
The "correct" mode means where the coolant is actually being circulated inside the cabin. 1999 Honda uses shut off valve in the engine to control whether the hot coolant will go through cabin or not. Based upon the inside temperature setting, the valve opens or shuts off accordingly. I am sure BMW has seven computers and fifteen actuators and thirty sensors to do something equivalent If something could be done using Rube Goldberg scheme, BMW would be the first to embrace it!
If the temperature setting was not on the high during the testing, the shop might not have seen the leak on their pressure test.
The "correct" mode means where the coolant is actually being circulated inside the cabin. 1999 Honda uses shut off valve in the engine to control whether the hot coolant will go through cabin or not. Based upon the inside temperature setting, the valve opens or shuts off accordingly. I am sure BMW has seven computers and fifteen actuators and thirty sensors to do something equivalent
If something could be done using Rube Goldberg scheme, BMW would be the first to embrace it!If the temperature setting was not on the high during the testing, the shop might not have seen the leak on their pressure test.
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Coolant loss and subsequent overheating is THE bane of bmw's. It begins between 60k-80k and either its caught and fixed, or it overheats once and the head warps and doesn't run right after.
The cooling system relies on lots of plastic to keep the weight down-- the integrated radiator/overflow, L-pipes off the engine, and various fittings are all black plastic. If you buy used, it's the first thing a savvy bmw hobbyist checks.
Usually the block doesn't warp, just the head--- so getting the head shaved is all it takes. However, the gasket can be hard to set just right (there's a tool for it) and if you mess up the cam/sprocket angle there's a tool needed for that too.
That said, watch your coolant level OFTEN until this is found and fixed. And when the problem is found, I would advise to replace ALL of the plastic parts--- radiator, engine coolant fittings, heater coolant fittings. Then you'll be good for another 60k-80k.
they can be fantastic cars but not without their quirks.
The cooling system relies on lots of plastic to keep the weight down-- the integrated radiator/overflow, L-pipes off the engine, and various fittings are all black plastic. If you buy used, it's the first thing a savvy bmw hobbyist checks.
Usually the block doesn't warp, just the head--- so getting the head shaved is all it takes. However, the gasket can be hard to set just right (there's a tool for it) and if you mess up the cam/sprocket angle there's a tool needed for that too.
That said, watch your coolant level OFTEN until this is found and fixed. And when the problem is found, I would advise to replace ALL of the plastic parts--- radiator, engine coolant fittings, heater coolant fittings. Then you'll be good for another 60k-80k.
they can be fantastic cars but not without their quirks.
That's the sweet smell of success
My friend has a BMW of about the same age. Does the AC run with the heater on? His evaporator was leaking inside the car. Not sure if it smelled sweet though. Just google BMW evaporator leak.
Yeah the AC runs with the heat. Its got one of those computerized temp controls where you set the temp and then it takes your suggestion and then does whatever it thinks it needs to do to get the temp to that spec. You can manually disable the AC by hitting a button. It seems like I still get the smell when I do that... I read through some of the posts about the evaporator leaking. Does AC refridgerant smell?
No idea if that stuff smells. Try put it on full cold and turn off the AC. Then see if it smells. Run it for a good few minutes. Smell some listerine and then get back on your car to clear your sense of smell. See if it still smells. What's interesting is you said it smells sweet, sometimes the vents get musty and moldy and stink, at least it's not that. Some people spray Lysol down the HVAC intake where the hood and windshield is to clear a bad smell.
If you have a mold/mildew smell problem, first you need to fix the condensation drain issue. Then you can fix the smell with a foaming coil cleaner like one of these:
http://www.amazon.com/FJC-5914-Foaming-Evaporator-Cleaner/dp/B002EAKX88
http://www.amazon.com/Foam-Coil-Cleaner-Evaporator-Condesor/dp/B007I7KZN0
http://www.amazon.com/gp/product/B0007PHD0S
http://www.amazon.com/FJC-5914-Foaming-Evaporator-Cleaner/dp/B002EAKX88
http://www.amazon.com/Foam-Coil-Cleaner-Evaporator-Condesor/dp/B007I7KZN0
http://www.amazon.com/gp/product/B0007PHD0S
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