Similar to the Mazda 6, the 626 runs on an engine that utilizes the serpentine belt system to drive various components in the engine, such as the alternator and the power steering pump. A single, continuous belt that runs throughout the engine, the serpentine belt can fray and break over time, causing a number of components in your engine to no longer work. If this happens, you need to install a new belt. While the exact model of 626 you own will dictate the number of pulleys and components your serpentine belt routes through, the overall installation procedure is identical in all models.
Park your Mazda 626 on a flat, level area so the vehicle cannot accidentally roll. Set the parking brake and allow the engine 30 minutes to cool down (if you have been driving it). Open the hood of the vehicle and use an adjustable wrench to loosen and remove the negative battery cable. Find the serpentine belt routing diagram on the underside of the hood and use it as a guide to locate the automatic belt tensioner pulley, as well as a reference to route the new belt through the pulleys of the engine (number of pulleys will vary depending on the exact model of 626 you drive).
Route the new serpentine belt, starting with the crankshaft pulley at the bottom of the engine. Reach this pulley by standing next to your car and reaching down through the engine to loop the belt over the pulley. Follow the path indicated on the diagram to route the belt through the remaining pulleys in the engine, with the tensioner pulley saved for last.
Find the belt tensioner pulley referenced on the serpentine belt diagram and locate the bolt that sticks out of the side of the pulley. Attach an appropriate-sized socket over the end of the bolt and attach the corresponding ratchet for leverage. Apply force to the ratchet and rotate it counterclockwise to loosen the tensioner pulley. Allow for several seconds of tension release before sliding the new belt over the tensioner pulley. Let the pulley return to its closed position to tighten the belt.
Replace the negative battery lead and close the hood of the 626. Start the engine and let the car run for several minutes before driving it to give the tensioner pulley time to adjust the tautness of the belt.
