The next time you work with a drive belt, timing belt, or timing chain, you’ll likely have to Car Pulley Belt loosen a tensioner pulley to remove it. Subsequent these general suggestions and specific instructions from your own owners manual or restoration manual, your belt or chain will function for the life of your car.
Toyota and additional 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 nearly always positioned in the timing case, mostly on automobiles with 
timing chains, while some are used with timing belts. Hydraulic tensioners are driven by oil pressure from the engine essential oil pump and could press on a tensioner pulley (timing belts) or pressure slipper (timing chain). You will likely need the year, make, and model information, 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, while the hydraulic damper keeps it from bouncing under load changes. This prevents timing belts and timing chains slapping and jumping the teeth and keeps 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 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 important.
To loosen an NAI tensioner, loosen the locking nut or bolt, then cool off the tensioner screw. Press the pulley toward the additional pulleys or components, loosening the belt.
Spring tensioner pulleys, as the name implies, use 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 adjustments and are less susceptible to user error.
