I've recently put an engine from a salvage Fortwo with around 40k miles on it and 2 days after the install it started making this sound.
I'm not sure if it's a belt or pulley because those came off of the old engine that had been sitting for 2 years but it makes this sound on cold starts and over 2k rpm. Has anyone heard this from their Smart before?
I use to have a metal tube with a push out wax-like substance to use on belts. If it was the belt squeaking, this substance would stop it immediately. Tube of stuff was probably from prehistoric auto times. 🤣
Thanks for the replies! Come to find out it the a/c belt was misaligned by one groove and it was rubbing on the belt cover. Put it where it was supposed to be and all has been well. Me and my dad were so happy to have the motor swapped in 2 days and it started up and ran so smooth.