2009 Acura MDX serpentine belt diagram with routing details and replacement guide

Check the routing of the serpentine belt before loosening any components, because proper alignment ensures that every accessory runs without issues. On the 2009 Acura MDX, the belt drives the alternator, power steering pump, air conditioning compressor, and water pump, all relying on precise tension.

The diagram shows a single belt wrapping around multiple pulleys in a specific order. The crankshaft pulley sits at the base, sending motion upward to the alternator and across to the other accessories. Misplacing the belt by one groove can cause squealing or premature wear, so following the diagram is critical during reinstallation.

Always release tension from the belt tensioner with the proper wrench or socket. Once the belt is free, compare the new belt length and rib count to the old one. This quick check prevents wasted effort and ensures a correct fit. After routing the new belt according to the diagram, reapply tension smoothly and verify alignment along each pulley before starting the engine.

2009 Acura MDX Serpentine Belt Diagram

Check the routing sticker under the hood first; if it’s missing, use this diagram to route the serpentine belt on a 2009 Acura MDX. The belt loops around the crankshaft pulley at the bottom, then wraps over the alternator on the upper right, around the idler pulley near the center, and down to the A/C compressor on the lower left. From there, it continues around the power steering pump on the upper left and finally across the tensioner pulley before completing the circuit back to the crankshaft.

Before removing the old belt, sketch the routing on paper or take a photo to avoid mistakes during installation. Use a 14 mm wrench on the tensioner pulley bolt to release pressure and slip the belt off. When installing the new belt, make sure it sits fully in the grooves of each pulley and check alignment carefully to prevent premature wear or noise.

After installation, rotate the crankshaft manually one full turn to confirm the belt tracks smoothly. Recheck tension and alignment, then start the engine and listen for any abnormal sounds. This quick inspection helps verify that every pulley engages correctly and that the new belt is ready for reliable operation.

Correct Belt Routing for 2009 Acura MDX Engine

Route the serpentine belt around the crankshaft pulley first, keeping the smooth side aligned with the tensioner pulley and the ribbed side aligned with grooved pulleys. From the crankshaft, guide the belt upward around the alternator, then loop it around the power steering pump on the passenger side.

Continue the path under the idler pulley, ensuring the belt teeth sit firmly in the grooves. Wrap the belt around the A/C compressor at the lower front, then move it up to the water pump pulley. Finish the routing by pulling the belt across the automatic tensioner.

Check each pulley for full contact before releasing the tensioner. A properly seated belt should rest flush in every groove without slack or twisting. After installation, rotate the crankshaft manually one full turn to confirm alignment and smooth movement across all pulleys.

Steps to Locate and Identify Each Pulley

Begin by finding the crankshaft pulley at the bottom of the engine bay. It is the largest pulley and drives the rest of the system, making it the easiest starting point.

Move upward to the alternator pulley, located near the top on the passenger side. Its compact size and direct connection to the alternator housing help you recognize it quickly.

Next, locate the power steering pump pulley on the upper driver’s side. This pulley is slightly recessed, with hoses leading from the pump that confirm its function.

Shift attention to the air conditioning compressor pulley near the bottom front on the passenger side. The attached compressor body and refrigerant lines make identification clear.

Continue by spotting the water pump pulley close to the center of the layout. It is round, smooth, and usually spins freely by hand when the belt is removed.

Finally, check the tensioner pulley and idler pulley. The tensioner pulley is spring-loaded and smaller, while the idler pulley appears similar but mounted in a fixed position. Both are key for proper belt alignment.

Signs the Serpentine Belt Needs Replacement

Check the belt regularly and replace it once you notice any of the following symptoms to avoid sudden breakdowns.

• Squealing noises: A high-pitched sound from the front of the engine often indicates a worn or loose belt.
• Visible cracks or fraying: Inspect the belt surface for cuts, missing ribs, or shredded edges that signal material fatigue.
• Glazing or shiny spots: A glossy finish on the rubber means the belt is slipping on pulleys and losing grip.
• Loss of power steering or AC issues: If steering feels heavy or the air conditioner stops cooling properly, the belt may not be driving accessories consistently.
• Battery warning light: Since the belt powers the alternator, electrical issues or a glowing battery light can point to slippage or failure.
• Engine overheating: A slipping or broken belt prevents the water pump from circulating coolant, causing temperature spikes.

Replace the belt every 60,000 to 100,000 miles or sooner if any of these warning signs appear, and always check tension and pulley alignment during inspection.