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So I have a problem with my 00 323ci. Losing significant coolant, but it is not puddling in the garage. Can smell a sweet smell when the heat is turned up into the cabin. Temperature gauge stays in the middle when idiling but will drop to the cold side when running for 25+ mins. With that the heat is not blowing hot into the cabin but when it is stopped and idiling, thus moving the needle to the middle of the temp gauge the heat will then start getting hot again.

Heard anything from expansion tank to heater core to head gasket. Any ideas or solutions to similar problems? Thank you very much
 

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Hey there,

first thing I'd do if i were you would be to try and figure out where the leak is coming from. Start with removing the splash shield. Next thing you can do is to remove the air box and take a good look at the expansion tank. They crack, mine did @ 60k.

BMW's have what is known as a closed system for cooling -- a leak usually means that something is broken. This is something that really isn't good to let go for to long, as something just hasn't catastrophically failed yet.

Thanks.
 

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Check for oil in coolant, or coolant in oil - if found then likely head gasket. But with smell of coolant in cabin it is more likely a leak in the heater core, or hoses to/from the heater core.
 

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So I have a problem with my 00 323ci. Losing significant coolant, but it is not puddling in the garage. Can smell a sweet smell when the heat is turned up into the cabin. Temperature gauge stays in the middle when idiling but will drop to the cold side when running for 25+ mins. With that the heat is not blowing hot into the cabin but when it is stopped and idiling, thus moving the needle to the middle of the temp gauge the heat will then start getting hot again.

Heard anything from expansion tank to heater core to head gasket. Any ideas or solutions to similar problems? Thank you very much
Hope I can help.

First, your thermostat has broken 'open,' and needs to be replaced.

Second, you have a leak and you'll want to find it. That it's not puddling, might mean that it's still a slight leak and only visible when your car is running. It might be leaking onto underskirt, but when you pull into garage and turn car off in your freezing temp, the engine cools so quickly that the pressure is relieved right away, so you're not puddling, or perhaps the underskirt is holding that which you've leaked. Then when you drive, it's blowing away and 'emptied' leaving room for the next round of leaking coolant to stay contained within your underskirt.

You might 'just' be leaking from the thermostat and it's dripping on hot engine, thus the smell. Almost always, it seems, the leak is from the seam at top of expansion tank...so when it's running, check there. Could also be from expansion tank cap...or one of the many hoses.

Many recommend replacing many things at first sign of this...expan tank, therm, upper and lower hoses and therm sensor.

Read all the many threads on coolant leaks and you'll see opinions vary somewhat...but your therm is broken and you have a leak from somewhere.

How much coolant you losing? Check level when engine is cool, you know.

Do some investigation, read some of the many threads, and let us know what you find. If you're handy with tools, it's all a DIY.

Doug
 

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IxNay,

Don't you think the smell could just be that the coolant has sprayed onto engine from maybe a leaking therm, or maybe the expansion tank crack is so fine, that the pressure is blowing it over to engine...then wafting through cabin air filter...same sort of thing when VCG blows and you smell oil in cabin.

Not to argue with you and your obvious greater experience with the cars as evidenced by your bizillion posts! LOL

D
 

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I would take a good look in the engine compartment but loss of coolant with no visible source, sweet smell in the heating system would point me to either heater core or valve or something else inside the dash.
 

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Hope I can help.

First, your thermostat has broken 'open,' and needs to be replaced.

Second, you have a leak and you'll want to find it. That it's not puddling, might mean that it's still a slight leak and only visible when your car is running. It might be leaking onto underskirt, but when you pull into garage and turn car off in your freezing temp, the engine cools so quickly that the pressure is relieved right away, so you're not puddling, or perhaps the underskirt is holding that which you've leaked. Then when you drive, it's blowing away and 'emptied' leaving room for the next round of leaking coolant to stay contained within your underskirt.

You might 'just' be leaking from the thermostat and it's dripping on hot engine, thus the smell. Almost always, it seems, the leak is from the seam at top of expansion tank...so when it's running, check there. Could also be from expansion tank cap...or one of the many hoses.
I agree here. Your Thermostat is done. The other reason you get no heat in the car is because of the loss of coolant. When the car looses coolant it drains the heating lines which become empty and you get air. Feel your heating lines are they will be empty. Also with the themostat open the car is not heating properly and the mix valve will not open properly to the heater core.

The sweet smell you are smelling is definately coolant. And I agree again with Doug that it is probably leaking somewhere but burning off/drying before it drips down to the lower sheild. Mine did that. Never a leak on the ground. On my friends, his leak in the expansion tank actually shot out toward the left rail and followed some lines attached to it and then went further back.

Also from the tanks I have seen that cracked, the leak so far has been on the lower left corner (if sitting in your car) of the expansion tank, very near the corner. It will be vertical along this corner and will be around the upper smaller hose near the bottom of the tank. Only way to see this will be by removing the air box.

Oh and the smell could be from the engine bay because your getting the smell through the fresh air cabin filter.
 

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I have had a very slow coolant leak for the last 30k miles or so. It is either the expansion tank itself or one of the hose connections to the tank.

What I experience is a sweet smell every morning. I'll start the car from cold and back out of the garage. Since my apt complex does not give remotes for the garages, I have to get out and press a button to close the garage. When I get out of the car, that's when I smell the sweet coolant. I'm wondering why I would smell it more when the car is cold vs when it has warmed up and hot, pressurized coolant would be more likely to spray out from wherever the leak is.
 
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