[toby_2028]

Car: E90 320D 184 HP M-Sport
Tre weeks ago, I did at full transmission service. I drained the oil, I pulled the mechatronic down, changes the 4x rubber pipe sealings and the transmission adapter rubber. I change the transmission sealing sleeve adaptor, the oil pan/filter and put it all back together. I drained 7.5 liters ATF oil, and pumped the same in again. The oil level is perfect at 30 degrease. All parts I used is OEM BMW ordered from BMW Germany directly. The part is the same as OEM ZF, just more expensive with the BMW logo on ☹
The Car only smells when I come to a stop. - It spells so bad that I drive with the windows open. – Winter is coming soon ☹
The smell started 200 km after the oil change and now stinks all the time.
Recirculating the air in the car only helps a bit.

There is NON ATF oil insite the car. - Carpets gear shifter etc.
There are absolutely NO LEAKS from the oil pan and around the gearbox.
The gearbox is NOT OVERFILLED.
The problem is NOT THE POWER STEERING leaking because the car uses electric power steering.

My question is:
Why does it smells og ATF throw the vents, when the car is hot and coming to a stop/very low speeds?

Please help me before I gas my family and end up in prison.
NB: I am certified mechanic myself.

[roadkillrob]

The one thing I can tell you is that the drain line for condensation to get out of the heat/ac box which sits kinda below and behind the radio is right on top of the transmission, so it can suck some air up that line when running also.

I cannot imagine the smell could be that strong if it isn't leaving a noticeable amount of ATF leaking out onto the undertray. When mine leaked I had a puddle and no smell at all in the car, so I would have to think it would need to maybe leak onto the exhaust to really get a smell (which would also make it not have a drip anywhere as it would burn off). Maybe check the exhaust for residue, I think it would be hard to get a leak specifically onto the exhaust but not impossible.

Other thought is coincidence and it is the VCG leaking onto the exhaust, that is very common and gets into the climate control very easily, but you seem to be sure it is ATF smell not engine oil.

[toby_2028]

Originally Posted by roadkillrob

The one thing I can tell you is that the drain line for condensation to get out of the heat/ac box which sits kinda below and behind the radio is right on top of the transmission, so it can suck some air up that line when running also.

I cannot imagine the smell could be that strong if it isn't leaving a noticeable amount of ATF leaking out onto the undertray. When mine leaked I had a puddle and no smell at all in the car, so I would have to think it would need to maybe leak onto the exhaust to really get a smell (which would also make it not have a drip anywhere as it would burn off). Maybe check the exhaust for residue, I think it would be hard to get a leak specifically onto the exhaust but not impossible.

Other thought is coincidence and it is the VCG leaking onto the exhaust, that is very common and gets into the climate control very easily, but you seem to be sure it is ATF smell not engine oil.

Vaccum in the clima drain when blower is on?

The drain for the clima is next to the gearbox vent, so that would make a ton of sens. That also explains why the spell is not effected by the air recirculation being on.

I think the smell is less and less, so let me get back in a few days with a new status.

UPDATE:
The smell is almost gone now. Maybe the ATF oil just smells when it is new. I have done 5000 KM and I change the oil one month ago.
I guess that the smell is completely gone in two months :-)

UPDATE II: The Smell is completely gone. The problem was definitely the new oil smell, sucking fumes throw the AC drain. About 7.000 and two months the smell was gone.

[Bmw330]

Did your smell dissapear over time? Or did you figure out what it was.

Have something similar when stationary, tried everything so far, it’s bone dry underneath!

[toby_2028]

Originally Posted by Bmw330

Did your smell dissapear over time? Or did you figure out what it was.

Have something similar when stationary, tried everything so far, it’s bone dry underneath!

UPDATE II: The Smell is completely gone. The problem was definitely the new oil smell getting throw the AC drain. About 7.000 and two months the smell was gone.

[Bmw330]

I’m on about 5000 miles now since it was changed, smell still there at idle although appears to be getting less frequent, hopefully a few more 000 miles it will go.......

[Welcome to NBA Jam]

ATF is really really smelly. It'll go away eventually. The smell doesn't leave my garage for nearly a month after a fluid change.

[Boland01]

I just changed the fluid, pan, mechtronic and solenoids. We had the same thing. The smell lasted a few days and is now gone. I think when I drained and pulled the pan (I let it sit over night) it probably splashed a little on another component possibly the exhaust.

Anyways no worries now and it shifts like new again.

[Bmw330]

Mine is still there after 6000 miles now, only when you stop though, wondering if it’s been overfilled and the vapour is coming out of the drain tube which appears to be at the top of the box?

Edit
7500 miles, virtually gone now, very occasional whiff which I’m sure will go. Worth considering that the smell can appear for some time after the change, so be very careful with where it spills! (Mine didn’t spill but could still smell it!)