Next time you work with a drive belt, timing belt, or timing chain, you’ll likely have to loosen a tensioner Car Pulley Belt pulley to eliminate it. Following these general recommendations and specific instructions from your own owners manual or restoration manual, your belt or chain will function for the life of your car.

Toyota and various other timing belt tensioners are loosened by simply removing them from the engine. You must slowly compress them in a bench vice and lock them with a pull-pin before reinstallation.
Hydraulic (not hydraulic-damped) tensioners are nearly always situated in the timing case, mostly on automobiles with timing chains, while some are used with timing belts. Hydraulic tensioners are driven by oil pressure from the engine essential oil pump and could press on a tensioner pulley (timing belts) or stress slipper (timing chain). You will likely need the year, make, and model info, and you may have to use special equipment for this kind of tensioner pulley.
Typically, a hydraulic tensioner must be “reset” and locked after removing it from the engine. Take away the lock only after the tensioner, pulley, or slipper, and timing belt or timing chain are installed and aligned.

The spring maintains tension, while the hydraulic damper keeps it from bouncing under load changes. This prevents timing belts and timing chains slapping and jumping the teeth and maintains drive belts from slipping and producing sound. To loosen a drive belt springtime tensioner pulley, refer initial to the repair manual or owners manual’s specific season, make, and model information.
You might need a special tool, but many spring tensioners have a square hole, for a 3/8” or 1/2” breaker bar, or a hex or square protrusion for a wrench or socket. Using the appropriate tool, release stress on the belt. You will have to hold some spring tensioners while slipping on a new belt. Others may have a locking mechanism, like a hole for a locking pin or hex crucial.

To loosen an NAI tensioner, loosen the locking nut or bolt, after that cool off the tensioner screw. Push the pulley toward the additional pulleys or accessories, loosening the belt.
Spring tensioner pulleys, since the name implies, make use of a springtime to hold tension upon the belt. Most, if not absolutely all, spring tensioner pulleys are NAI tensioners and include a hydraulic damper. They are more technical and expensive but don’t require modifications and are less prone to user error.