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 restoration 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 situated in the timing case, mostly on automobiles with timing chains, while some are used in combination with timing belts. Hydraulic tensioners are powered by essential oil pressure from the engine essential oil pump and could press on a tensioner pulley (timing belts) or tension slipper (timing chain). You will likely need the year, make, and model information, and you may need to use Car Pulley Belt special tools 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 set up 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 will keep drive belts from slipping and producing sound. To loosen a drive belt spring tensioner pulley, refer initial to the repair manual or owners manual’s specific year, make, and model details.
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 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 essential.

To loosen an NAI tensioner, loosen the locking nut or bolt, then cool off the tensioner screw. Push the pulley toward the additional pulleys or components, loosening the belt.
Spring tensioner pulleys, because 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 complex and expensive but don’t require modifications and are less susceptible to user error.