Next time you work with a drive belt, Car Pulley Belt timing belt, or timing chain, you’ll likely need to loosen a tensioner pulley to remove it. Subsequent these general suggestions and specific instructions from your owners manual or restoration manual, your belt or chain will function for the life of your car.
Toyota and other timing belt tensioners are loosened simply by removing them from the engine. You need to slowly compress them in a bench vice and lock them with a pull-pin before reinstallation.
Hydraulic (not hydraulic-damped) tensioners are almost always situated in the timing case, mostly on automobiles with timing chains, while some are used with timing belts. Hydraulic tensioners are run by essential oil pressure from the engine essential oil pump and could press on a tensioner pulley (timing belts) or stress slipper (timing chain). You’ll likely need the year, make, and model information, and you may need to use special equipment for this sort 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 tooth and helps to keep drive belts from slipping and producing sound. To loosen a drive belt springtime tensioner pulley, refer first to the repair manual or owners manual’s specific year, make, and model info.
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 correct tool, release stress on the belt. You will have to hold some spring tensioners while slipping on a new belt. Others may possess a locking mechanism, such as a hole for a locking pin or hex important.
To loosen an NAI tensioner, loosen the locking nut or bolt, after that cool off the tensioner screw. Drive the pulley toward the additional pulleys or add-ons, loosening the belt.
Spring tensioner pulleys, as the name implies, use a spring to hold tension upon the belt. Most, if not absolutely all, springtime tensioner pulleys are NAI tensioners you need to include a hydraulic damper. They are more complex and expensive but don’t require adjustments and are less prone to user error.