The next time you work with a drive belt, timing belt, or timing chain, you’ll likely have to loosen a tensioner pulley to eliminate it. Following these general suggestions and specific guidelines from your own owners manual or repair 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 nearly always located in the timing case, mostly upon automobiles with timing chains, though some are used in combination with timing belts. Hydraulic tensioners are driven by oil pressure from the engine oil pump and may press on a tensioner pulley (timing belts) or stress slipper (timing chain). You’ll likely need the entire year, make, and model information, and you may have to use special tools for this type of tensioner pulley.
Typically, a hydraulic tensioner needs to be “reset” and locked after removing it from the engine. Remove 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 the teeth and retains drive belts from slipping and making noise. To loosen a drive belt springtime tensioner pulley, refer 1st to the restoration 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 appropriate tool, release tension on the belt. You’ll need to hold some springtime tensioners while slipping on a new belt. Others may have a locking mechanism, such as a hole for a locking pin or hex crucial.
To loosen an NAI tensioner, loosen the locking nut or bolt, then back off the tensioner screw. Press the pulley toward the additional pulleys or add-ons, loosening the belt.
Spring tensioner pulleys, as the name implies, make use of a springtime to hold tension on the belt. Most, if not all, springtime tensioner pulleys are NAI tensioners and include a hydraulic damper. They are more technical and expensive but don’t require adjustments and are less susceptible to user error.