Serpentine Belt Tensioner
A spring-loaded pulley system designed to maintain the optimal tension on the serpentine belt to prevent slipping and belt squeal.
The serpentine belt tensioner is an accessory drive component featuring a spring-loaded arm and a pulley. Its primary purpose is to apply a constant, pre-set mechanical pressure to the serpentine belt, ensuring it wraps tightly around the pulleys of the alternator, water pump, power steering pump, and air conditioning compressor.
This prevents the belt from slipping under heavy electrical or mechanical loads. The internal tensioner spring can weaken over time, or the pulley bearing can dry out and seize.
A failing tensioner can cause squealing or chirping noises, excessive belt vibration, uneven belt wear, or belt throwing, which results in an immediate loss of all engine accessories. Replacing the tensioner along with a new serpentine belt is a recommended service.