Q: Thumping noise after replacing motor mounts & tranny

Hello. The thumping noise that you hear is probably coming from one of the motor mounts that was replaced. The bolts that hold the mount down could be loose or it is possible that one of the mounts are defective. If the overdrive light is flashing this usually means that there is a problem with the overdrive gear. It would be a good idea to take your vehicle back to the transmission shop where you transmission and motor mounts were installed and have them inspect the mounts for damage or loose bolts as well as the transmission. If you still have a warranty on the transmission, it is possible that this can be corrected under warranty. If you need additional help, a certified mobile mechanic from YourMechanic can visit your home or office to inspect the source of the noise.