The next time you work with a drive belt, timing belt, or timing chain, you’ll likely need to loosen a tensioner Car Pulley Belt 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 vehicles with timing chains, though some are used in combination with timing belts. Hydraulic tensioners are powered by oil pressure from the engine oil pump and may press on a tensioner pulley (timing belts) or pressure slipper (timing chain). You will likely need the year, make, and model info, and you may need to use special equipment for this sort of tensioner pulley.
Typically, a hydraulic tensioner needs to 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, as the hydraulic damper keeps it from bouncing under load changes. This prevents timing belts and timing chains slapping and jumping teeth and maintains drive belts from slipping and making noise. To loosen a drive belt springtime tensioner pulley, refer initial to the repair manual or owners manual’s specific yr, 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 correct tool, release tension 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 important.

To loosen an NAI tensioner, loosen the locking nut or bolt, then cool off the tensioner screw. Drive the pulley toward the other pulleys or accessories, loosening the belt.
Spring tensioner pulleys, because the name implies, use a springtime 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 modifications and are less susceptible to user error.