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2018 XC90 T6 Engine Squeal - Serpentine Belt or Tensioner?

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Chris P. · rep 0 · May 22, 5:17 AM · 1 replies · solved · Question

Vehicle: 2018 Volvo XC90 T6

Hey everyone,

I've got a 2018 Volvo XC90 T6 with about 75,000 miles on it, and I've started noticing a distinct squealing noise coming from the engine bay. It's most prominent on cold starts and sometimes when accelerating from a stop. It sounds like it's coming from the passenger side of the engine.

I'm thinking it might be the serpentine belt or possibly a failing tensioner or idler pulley. I haven't had any issues with power steering or AC, but the noise is definitely getting louder. I'm pretty handy and would like to tackle this myself if it's a straightforward DIY.

Has anyone experienced this with their XC90 T6? What's the best way to diagnose it definitively? Any tips or special tools needed for replacing the belt or tensioner on this model?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 5:17 AM

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ClearTheCode admin answer:

It sounds like you're on the right track with suspecting the serpentine belt or its associated components. A squealing noise, especially on cold starts or acceleration, is a classic symptom of a worn or loose drive belt, or a failing pulley/tensioner. Here's how to approach it:

  1. Visual Inspection:

    • With the engine off and cool, carefully inspect the serpentine belt for cracks, fraying, glazing (shiny appearance), or missing ribs. A flashlight can help. Pay close attention to the underside of the belt.
    • Check all pulleys (alternator, AC compressor, power steering pump, idler pulleys, tensioner pulley) for excessive wobble, play, or signs of grease leakage. Spin them by hand (engine off!) to feel for roughness or resistance.

  2. Water Spray Test (Caution!):

    • Only perform this if you are comfortable and cautious. With the engine running and the squeal present, lightly spray a small amount of water onto the ribbed side of the serpentine belt. If the squeal temporarily stops or changes, it strongly indicates the belt itself is the issue. If it doesn't change, the problem might be a pulley or tensioner.

  3. Causes:

    • Worn Belt: Over time, belts harden, crack, and lose their grip.
    • Failing Tensioner: The automatic tensioner maintains proper belt tension. If it weakens or seizes, the belt can become loose and slip.
    • Bad Idler Pulley: Bearings in idler pulleys can wear out, causing noise and drag.
    • Accessory Component: Less common, but a failing bearing in an alternator, AC compressor, or power steering pump can also cause a squeal.

  4. DIY Replacement Tips for XC90 T6:

    • Tools: You'll typically need a serpentine belt tool (a long wrench with a square drive to release tension), a new belt, and potentially new idler/tensioner pulleys. A torque wrench is recommended for proper reinstallation.
    • Procedure: Locate the tensioner pulley. Insert the serpentine belt tool into the square hole on the tensioner and rotate it to release tension. Carefully remove the old belt, noting its routing. Install the new belt, ensuring it's correctly routed over all pulleys before releasing the tensioner.
    • Volvo Specifics: On some Volvo models, access can be tight. You might need to remove an engine cover or air intake components for better access. Always refer to your vehicle's service manual for exact torque specifications and routing diagrams.

When to See a Shop: If the noise persists after replacing the belt, or if you're uncomfortable with the diagnosis or replacement process, it's best to take your XC90 to a qualified mechanic. A professional can use a stethoscope to pinpoint the exact source of the noise and ensure no other underlying issues are present, such as a failing accessory component that could lead to more significant repairs if left unaddressed.

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