If you follow the path of the serpentine belt on the engine, you will find it goes over several auxiliary pulleys. It also goes over a small belt tensioner pulley. A belt tensioner is a small component with four main parts:

Base: The metal part that holds all other parts

Tensioner Arm: Located at the bottom of the tensioner; applies pressure to the belt with enough slack to help you adjust or remove the belt

Spring: Provides pressure to keep the tensioner tensioned

Pulley: The rotating part that moves the belt

For the most part, all belt tensioners look the same. Some are bigger, and some are smaller. However, the design remains more or less the same.

The belt tensioner is always in the path of the serpentine belt. Its pulleys are smaller than others on this path, so it's easy to identify. If you look at the Mazda CX7 engine, you will find the belt tensioner on the right.

A spring-loaded arm on the tensioner applies pressure to the belt. The whole point of having a belt tensioner on an engine is to keep the serpentine belt tight enough. If the belt is too loose, it won't provide enough power to any accessories.

A spring-loaded arm on the tensioner applies pressure to the belt. The whole point of having a belt tensioner on an engine is to keep the serpentine belt tight enough. If the belt is too loose, it won't provide enough power to any accessories.

NingBo GSK Powder Metallurgy Co., Ltd. is a belt tensioner pulley factory, which manufactures MIM-Lock Case, MIM-Lock Parts, etc. Welcome to inquire.