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2021 Yukon XL 6.2L V8 - Engine Ticking/Knocking Noise on Cold Start

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Steve N. · rep 0 · May 22, 3:39 AM · 1 replies · solved · Question

Vehicle: 2021 GMC Yukon XL Denali

Hey forum, I've got a 2021 GMC Yukon XL Denali with the 6.2L V8 engine, and I've noticed a concerning ticking or light knocking noise, especially when I start it up cold in the mornings. It seems to quiet down a bit once the engine warms up, but it's still audible.

I'm worried about the engine's health, especially with all the talk about lifter issues in these GM V8s. The truck only has about 30,000 miles on it, so I wouldn't expect major engine problems this early.

Has anyone else experienced a similar ticking or knocking noise with their 6.2L Yukon or Sierra? What was the cause, and what was the fix? Is this something I should be really concerned about, or could it be normal injector noise?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:39 AM

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ClearTheCode admin answer:

A ticking or light knocking noise, particularly on cold start, in your 2021 GMC Yukon XL Denali with the 6.2L V8 engine is a common concern among owners and can indicate several potential issues, some more serious than others.

  1. Common Causes:

    • AFM/DFM Lifter Issues: This is a very common and serious concern with GM's V8 engines equipped with Active Fuel Management (AFM) or Dynamic Fuel Management (DFM). Lifters can fail, causing a distinct ticking or knocking sound, especially when cold or under specific operating conditions. If a lifter collapses, it can lead to misfires and potentially camshaft damage.
    • Fuel Injector Noise: Direct injection engines, like your 6.2L, naturally produce a louder 'ticking' sound from the fuel injectors as they operate at very high pressures. This is often more noticeable when cold and can sometimes be mistaken for a mechanical issue. This noise is generally consistent and doesn't change significantly with engine load.
    • Exhaust Manifold Leak: A small exhaust leak, especially when the engine is cold, can produce a ticking sound that often diminishes as the engine warms up and the metal expands.
    • Piston Slap: Less common in newer engines, but some engines can exhibit a slight 'piston slap' noise when cold due to manufacturing tolerances, which usually disappears once the engine reaches operating temperature.

  2. Initial Diagnostic Steps:

    • Pinpoint the Source: Try to localize the sound. Is it coming from the top of the engine (valve covers), the side, or underneath? A mechanic's stethoscope can be very helpful here.
    • Listen for Consistency: Does the noise change with engine RPM? Does it go away completely when warm, or just quiet down? Does it sound like a consistent tick or a more irregular knock?

  3. When to See a Shop:

    • Given the prevalence of AFM/DFM lifter issues in these engines, any persistent ticking or knocking noise, especially one that doesn't sound like typical injector noise, should be investigated by a GMC dealership or a reputable mechanic. It's crucial to differentiate between normal injector noise and a failing lifter.
    • A professional can use specialized listening tools and diagnostic procedures to determine the exact source of the noise. If it is determined to be a failing lifter, addressing it early can prevent more extensive and costly engine damage, such as camshaft wear or even complete engine failure. Do not ignore a persistent mechanical noise from your engine.
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