New From Dayco, Hydraulic Automatic Timing Belt Tensioners ensure proper transmission efficiency for the entire life of the timing belt. This is achieved by the Hydraulic Automatic Tensioner keeping constant correct tension on the timing belt during engine operation. Compared with fixed type timing belt tensioners, timing belt life is increased, along with other timing drive train components such as pulleys and bearings. All Dayco Hyrdaulic tensioners meet or exceed OEM specifications.