Next time you work with a drive belt, timing belt, or timing chain, you’ll likely have to loosen a tensioner pulley to remove it. Following these general recommendations and specific guidelines from your owners manual or repair 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 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 located in the timing case, mostly on automobiles with timing chains, while some are used with timing belts. Hydraulic tensioners are powered by essential oil pressure from the engine essential 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 sort of tensioner pulley.
Typically, a hydraulic tensioner must 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 teeth and helps to keep drive belts from slipping and producing noise. To loosen a drive belt springtime 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 correct tool, release pressure on the belt. You will have to hold some springtime 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, after that cool off the tensioner screw. Force the pulley toward the other pulleys or components, loosening the belt.
Spring tensioner pulleys, since the name implies, use a springtime to hold tension upon 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 changes and are less susceptible to user error.