You might not be able to see it, but an accessory drive belt is always both speeding up and slowing down.
Belt tension creates friction between the belt and the pulleys. This video is sponsored by Litens.
A worn automatic belt tensioner has consequences beyond a loose belt.
Modern crankshaft position sensors measure more than the position of the crankshaft.
Misalignment and bearing wear can cause the belt to track off-center.
Andrew Markel describes the usage of a krikit gauge and how it can inform you of the health of an accessory belt. Sponsored by Continental.