Next time you utilize a drive belt, timing belt, or timing chain, you'll likely have to Car Pulley Belt loosen a tensioner pulley to eliminate it. Following these general recommendations 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 various 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 positioned in the timing case, mostly upon vehicles with timing chains, while some are used in combination with timing belts. Hydraulic tensioners are powered by oil pressure from the engine essential oil pump and may press on a tensioner pulley (timing belts) or stress slipper (timing chain). You will likely need the year, make, and model info, and you may have to use 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 following 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 retains drive belts from slipping and producing noise. To loosen a drive belt springtime tensioner pulley, refer 1st to the repair manual or owners manual's specific yr, make, and model info.
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 tension on the belt. You will have to hold some springtime tensioners 
while slipping on a new belt. Others may possess a locking mechanism, such as 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. Force the pulley toward the other pulleys or components, loosening the belt.
Spring tensioner pulleys, as the name implies, make use of a spring to hold tension on the belt. Most, if not absolutely all, spring 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.