The next time you utilize a drive belt, timing belt, or timing chain, you’ll likely need to loosen a tensioner pulley to eliminate it. Following these general guidelines and specific instructions from your owners manual or repair manual, your belt or chain will function for the life of your car.

Toyota and additional timing belt tensioners are loosened by simply removing them from the engine. You must 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 automobiles with timing chains, though some are used in combination with timing belts. Hydraulic tensioners are driven by essential oil pressure from the engine oil pump and may press on a tensioner pulley (timing belts) or pressure slipper (timing chain). You’ll likely need the entire year, make, and model details, and you may need to use special equipment for this kind 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 the teeth and helps to keep drive belts from slipping and making noise. To loosen a drive belt spring tensioner pulley, refer first to the restoration manual or owners manual’s specific calendar year, 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 Car Pulley Belt appropriate tool, release tension on the belt. You will have to hold some spring tensioners while slipping on a new 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, then cool off the tensioner screw. Push the pulley toward the other pulleys or add-ons, loosening the belt.
Spring tensioner pulleys, since the name implies, use 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 technical and expensive but don’t require changes and are less prone to user error.