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Squealing noise from engine bay on 2018 Navigator - time for new serpentine belt?

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Mike T. · rep 0 · May 25, 4:31 AM · 1 replies · solved · Question

Vehicle: 2018 Lincoln Navigator Reserve

Hello fellow Lincoln owners,

I've got a 2018 Lincoln Navigator Reserve, and lately, I've been hearing a distinct squealing noise coming from the engine bay. It's most noticeable on cold starts, especially in the morning, and sometimes when I turn on the AC. It usually fades after a few minutes of driving, but it's starting to get more frequent.

My first thought is the serpentine belt. The truck has about 70,000 miles on it. Is this a common symptom of a worn belt on these Navigators? Is replacing the serpentine belt a reasonably straightforward DIY job, or should I take it to a shop?

Any insights or advice on diagnosing and fixing this would be greatly appreciated!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 4:31 AM

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ClearTheCode admin answer:

A squealing noise from the engine bay, particularly on cold starts or when accessories like the AC are engaged, is a classic symptom of issues with the serpentine belt or its related components. At 70,000 miles, it's definitely time to inspect it on your 2018 Lincoln Navigator Reserve.

Here's what you should check:

  1. Inspect the Serpentine Belt:
    • Cracks and Fraying: Look for visible cracks, fraying, or missing ribs on the belt surface.
    • Glazing: A shiny, glazed appearance on the belt can indicate it's hardened and losing its grip.
    • Tension: While the automatic tensioner should maintain tension, ensure it's not seized or loose.
  2. Potential Causes of Squealing:
    • Worn Belt: The most common cause. The rubber hardens and loses flexibility.
    • Failing Belt Tensioner: The tensioner maintains proper belt tension. If it's weak or seized, the belt can slip and squeal. Listen for grinding or rattling from the tensioner pulley.
    • Worn Idler Pulley: Similar to the tensioner, a worn idler pulley can create noise. Spin them by hand (with the belt off) to check for roughness.
    • Failing Accessory Pulley: Issues with the alternator, power steering pump, or AC compressor pulley bearings can also cause squealing.
  3. DIY Replacement: Replacing the serpentine belt on a 2018 Navigator (with the 3.5L EcoBoost) is generally considered a moderate DIY job. You'll need:
    • A new serpentine belt (ensure it's the correct length for your engine).
    • A serpentine belt tool or a long-handled wrench/ratchet to release the tensioner.
    • A diagram of the belt routing (usually found under the hood or in your owner's manual).
    • Steps: Release tension, remove old belt, route new belt correctly, release tensioner, and ensure belt is seated.
  4. When to See a Shop:
    • If you're uncomfortable performing the replacement yourself.
    • If the noise persists after replacing the belt.
    • If you suspect a failing accessory component (alternator, AC compressor, power steering pump) or a seized tensioner/idler pulley, as these might require specialized tools or expertise. A failing belt can lead to loss of power steering, charging system failure, or AC, so address it promptly.
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