I’m experiencing an odd issue with my 2021 Silverado 1500 5.3 after having the transmission fluid replaced along with a new filter. Ever since the service, and the truck is idling with the A/C or heat on, there’s a noticeable exhaust-like, oil-like smell in the cab. I never had this issue before the service, so something seems off.
I went back to the shop that did the work, and they told me everything looks fine and suggested I just replace the cabin air filter. However, I’m skeptical because this smell started immediately after the service, and I never noticed it before.
Has anyone experienced anything like this after a transmission fluid change or filter replacement? Could something have gone wrong during the service that’s causing this smell? Any insight or suggestions would be greatly appreciated!
If the transmission was overfilled. it can cause transmission fluid vapors to be forced out the vent/breather of the transmission. And if the vapors come in contact with anything hot it can cause that smell.
I think you have the 10L80 (10 speed auto) transmission, and the Y-pipe (exhaust cross over pipe) runs either below or very close to the transmission pan, (pretty sure below it at the back and no drain plug for the pan, normal to do this), so when you remove the trans pan, you dump/spill ATF all over the Y-pipe…
It is very hard to overfill the transmission if brought up to the correct temp before installing the fluid level case plug… That is why it is important to only let qualified mechanics do trans services on these dipstickless transmissions…
Now if it was not brought up to the correct temp, then it was probably overfilled as ATF expands with heat (and I think these trans run hotter than normal), and anything hydraulic if/when overfilled will basically push what is not wanted out the vent tube…
I would just get it out on the interstate and drive it (for maybe 30 minutes) a little hard to try and burn off that spilt fluid and finish pushing out any fumes/ATF out the vent if overfilled any…