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2020 Envision 2.0T - Engine Rattle on Startup, Possible Timing Chain Noise

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Mike T. · rep 0 · May 25, 2:44 AM · 1 replies · solved · Question

Vehicle: 2020 Buick Envision Essence

Hi everyone,

I own a 2020 Buick Envision with the 2.0L turbocharged engine, and I've started noticing a concerning noise. When I first start the car, especially after it's been sitting overnight, there's a distinct rattling or clattering sound coming from the engine. It usually lasts for about 2-5 seconds and then quiets down, but it's definitely getting more noticeable.

The car has about 55,000 miles on it, and I've been pretty diligent with oil changes. I'm worried this might be related to the timing chain, as I've heard some GM 2.0T engines can have issues with them. There's no check engine light yet, and the car seems to drive fine otherwise, but that startup rattle is really unsettling.

Has anyone experienced this with their Envision or other 2.0T Buick models? What should I be looking for, or what was your experience with fixing it?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 2:44 AM

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ClearTheCode admin answer:

An engine rattle on startup, particularly after sitting, that lasts for a few seconds on a 2020 Buick Envision with the 2.0L turbocharged engine (LTG/LHU) is a classic symptom of timing chain stretch or issues with the timing chain tensioner. This is a known concern for these engines.

Common Causes & Diagnostic Steps:

  1. Timing Chain Stretch: Over time and mileage, the timing chain can stretch. When the engine is off, the chain tensioner (which is oil-pressure actuated) can lose some pressure. On startup, it takes a few seconds for oil pressure to build up and properly tension the chain, causing the rattle.
  2. Timing Chain Tensioner Failure: The hydraulic tensioner itself can fail or become weak, failing to maintain proper tension on the chain, especially at startup before full oil pressure is achieved.
  3. VVT Actuator/Cam Phasers: Issues with the Variable Valve Timing (VVT) actuators (also known as cam phasers) can sometimes contribute to startup noise if they are slow to build oil pressure or are worn.
  4. Low Oil Pressure/Incorrect Oil: While you're diligent with oil changes, using the incorrect oil viscosity or having low oil pressure (due to other issues) can exacerbate timing chain noise, as the tensioner relies on oil pressure.

When to See a Shop:

  • Immediately: While the car might seem to drive fine now, a stretched timing chain or failing tensioner is a serious issue. If the chain stretches too much or the tensioner completely fails, the chain can jump a tooth or break, leading to catastrophic engine damage (bent valves, piston damage). Do not delay diagnosis.
  • Professional Diagnosis: A Buick dealership or a reputable independent shop specializing in GM vehicles should perform the diagnosis. They will:
    • Listen to the engine carefully to confirm the source of the noise.
    • Scan for any pending or historical diagnostic trouble codes (DTCs) related to camshaft position or timing, such as P0016 (Crankshaft Position - Intake Camshaft Position Correlation Bank 1 Sensor A) or P0017 (Crankshaft Position - Exhaust Camshaft Position Correlation Bank 1 Sensor B). These codes often indicate timing chain stretch.
    • May perform a visual inspection of the timing chain components, which often requires partial engine disassembly.
    • Check oil pressure to rule out related issues.
  • Repair: If timing chain stretch is confirmed, the repair typically involves replacing the timing chain, tensioner, guides, and sometimes the VVT actuators. This is a labor-intensive repair.
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