How to Loosen a Serpentine Belt Tensioner

So, you need to know how to loosen a serpentine belt tensioner. There are three types of tensioners that may be encountered when replacing a serpentine belt. Most domestic vehicles use a spring-loaded tensioner. This is a smooth pulley attached to a short arm with a round thick shoulder at the end with a singular bolt in the center securing it to the block. These incorporate a heavy coil spring, which applies the tension.

It may seem like the manufacturer placed the tensioner in a spot as a poor attempt at humor. It couldn't be any harder to get to. One example of these are front wheel drive vehicles with tensioners in the lower half of the engine, below the side motor mount, and with one inch or less between the frame and the pulley. These tensioners will either have a 3/8- or a ½-inch slot in the arm or a ½-inch square protrusion. The slots require a long ratchet and the protrusion needs a box end wrench.

These types of belts may be so close to the frame it is not obvious how to reach it. Use a flashlight to identify the type of provision it has to move it, either the slot or protrusion. A long extension may and may not work because of the clearance. It may be necessary to purchase a tensioner release tool from an auto parts store that is made for the vehicle. This tool is a very thin flat two-foot long ratcheting box end wrench. They also have a short ½-inch nub on the other side of the wrench made to slip into close quarters.

Many front wheel drive vehicles with very close frame-to-engine pulleys need to have the belt installed from the bottom. There is no room to install the belt from the top, as your hands will not fit between the frame. If this is the case, the vehicle must be raised with a floor jack, the tire/wheel assembly must be removed, and the inner splash shield must be removed to gain access to the crankshaft pulley.

Some of these hard-to-get tensioners can be accessed from the bottom with a common ratchet or wrench. In any event, once accessed, connect the tool and pull the tensioner away from the belt, remove the belt from one pulley, and release the tensioner.

A coat hanger is a good idea to reach down from the top and grab the belt or to hold it in place on the top.

Domestic vehicles such as the Jeep Cherokee have a sliding tensioner pulley. This is located on the driver's side of the engine under the alternator. This tensioner operates by causing the alternator to swing out to put tension on the belt. There are two bolts that are used in the adjustment process. The bracket under the alternator has a slot with which the alternator can swing. The bolt that runs through the alternator must be loosened to allow the alternator to swing. Next, the bolt under the alternator that runs through the bracket must be turned which causes the alternator to swing. Once the tension is corrected, the first bolt through the alternator must be tightened to hold it in this position. This type of tensioner is located on many of the foreign vehicles at one location or another on the front of the engine.

Another type of tensioner used on foreign and domestic vehicles is the sliding adjustable pulley type. This is an easily adjustable tensioner. It consists of an engine-mounted flat bracket with a forward facing slot. There is a long bolt running from the top of the bracket down. The pulley has a provision in the back of it for this long bolt to thread into. The bolt, when turned, raises or lowers the pulley applying tension.

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