The 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 guidelines and specific guidelines from your own owners manual or repair manual, your belt or chain will function for the life of your car.

Toyota and other timing belt tensioners are loosened by simply removing them from the engine. You must gradually compress them in a bench vice and lock them with a pull-pin before reinstallation.
Hydraulic (not hydraulic-damped) tensioners are nearly always located in the timing case, mostly on automobiles with timing chains, though some are used with timing belts. Hydraulic tensioners are run 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 entire year, make, and model info, and you may need 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 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 producing sound. To loosen a drive belt springtime tensioner pulley, refer initial to the restoration manual or owners manual’s specific season, make, and model details.
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 fresh belt. Others may possess a locking mechanism, like a hole for a locking pin or hex key.

To loosen an NAI tensioner, loosen the locking nut or bolt, after that cool off the tensioner screw. Push the pulley toward the various other pulleys or components, loosening the belt.
Spring tensioner pulleys, since the name implies, use a springtime to hold tension on the belt. Most, if not all, springtime tensioner pulleys are NAI tensioners you need to include a hydraulic damper. They are more complex and costly but don’t require changes and are less prone to user error.