ATF smell after transmission fluid and filter change?

[daytona90t]

I am wondering if anyone has any insight here? I finished up my auto transmission fluid and filter change about 3 weeks ago now and am periodically still getting an ATF smell through my dash vents and from under the car on shutdown, most notably after a longer highway run. I used a new OEM Filtran filter, GM gasket, new fill and drain plugs and Redline D4. I did an initial drain and refill, drove the car for a few weeks and then dropped the pan and finished the job, I did not have the ATF smell issue with the first drain and refill. I followed the procedure by the book, oil pan was level in all directions, fill cold, run through the gears, heat fluid up to 30 Celsius (verified with fancy new BMW scan tool) and topped off while running. I also didn’t spill so much that it isn’t all cleaned up, dried up, or burnt off by now.

I have been under the car twice now with a lighted mirror tool and shop light and cannot find any indication of a leak, the pan and everything else all around is completely dry. Considering I just clocked in at 108,000 miles the car shift absolutely perfect in both auto and sport mode, smother and better than it ever has before. I just did the same job this past weekend on my 09 X3 with the GM 6-speed transmission, followed the exact same procedure, and don’t seem to be having any issues with any ATF smell. The only thing I came across is that it is possibly overfilled causing fluid and or vapors to be released by the vent/purge valve on the top of the transmission housing. I’m not sure how this could have happened being that I followed the procedure, and definitely don’t see any fluid being released.

This weekend I may run it up to temp and pull the fill plug to see how much comes out, but don’t think that I could have overfilled it so much as to cause an issue. Has anyone else ever had this issue after a fluid and filter change?

[WOLFN8TR]

I had the same problem on my ZHP when I changed the trans oil. All it takes is getting a little bit on the exhaust etc and it will smell bad! Mine went away after a week. You could get some engine degreaser and spray everything down.

[daytona90t]

I had the same problem on my ZHP when I changed the trans oil. All it takes is getting a little bit on the exhaust etc and it will smell bad! Mine went away after a week. You could get some engine degreaser and spray everything down.

I am going to give it some more time and see if the smell dissipates and completely goes away, then maybe try to clean it if it does not. I can’t actually see that there is any fluid anywhere, though I wonder if some could have dripped on top of the exhaust heat shield from the right side of the transmission when the pan was off and I was letting it drip for a while. My main concern is that it is leaking somewhere that I can’t see, doubtful though as I can see the whole pan lip, selector shaft, cooler lines, and plugs, or that I overfilled it, though it doesn’t seems that the GM 5L40E has any sort of purge or release valve where fluid or vapors could be released from.

[Dave1027]

You need to spray the area around the drain bolt and especially the fill bolt with brake cleaner as the last step in the atf change process to avoid the atf smell.

[RUS_ZHP]

I noticed the same thing, when I changed mine. Strangely, smell was only present during two very longs trips I did. I never noticed that while siting in the traffic.
I will definitely give brake cleaner a try next time

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