Next time you utilize a drive belt, timing belt, or timing chain, you’ll likely need to loosen a tensioner pulley to remove it. Following these general suggestions and specific guidelines from your owners manual or restoration manual, your belt or chain will function for the life span of your car.

Toyota and other timing belt tensioners are loosened by simply removing them from the engine. You need to gradually 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 upon vehicles with timing chains, while some are used with timing belts. Hydraulic tensioners are run by oil pressure from the engine oil pump and may press on a tensioner pulley (timing belts) or tension slipper (timing chain). You’ll likely need the year, make, and model details, and you may have to use special tools for this type of tensioner pulley.
Typically, a hydraulic tensioner needs to be “reset” and locked after removing it from the engine. Remove the lock only after the tensioner, pulley, or slipper, and timing belt or timing chain are set up 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 retains drive belts from slipping and making noise. To loosen a drive belt spring tensioner pulley, refer first to the repair manual or owners manual’s specific season, make, and model information.
You may 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 pressure on the belt. You’ll need to hold some spring tensioners while slipping on a fresh belt. Others may have a locking mechanism, like a hole for a locking pin or hex essential.

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