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2016 328i N20 Timing Chain Rattle - What's Next?

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Chris P. · rep 0 · May 25, 2:58 AM · 1 replies · solved · Question

Vehicle: 2016 BMW 328i xDrive

Hey everyone,

I've got a 2016 BMW 328i xDrive with the N20 engine, just hit around 95,000 miles. Lately, I've been hearing a distinct rattling noise from the engine bay, especially at idle and low RPMs. It sounds like it's coming from the front of the engine, almost like a metallic scraping or buzzing.

I've read online that the N20/N26 engines are notorious for timing chain guide issues, and I'm really worried this is what I'm experiencing. The car still drives fine for now, no warning lights, but the sound is getting more noticeable.

Has anyone else dealt with this on their 2015-2016 328i? What were your symptoms, and what was the fix? Should I be worried about catastrophic failure if I keep driving it? Any advice on how to confirm this without tearing the engine apart?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 2:58 AM

0

ClearTheCode admin answer:

It sounds like you're correctly identifying a common issue with the N20/N26 engines, specifically regarding the timing chain and its guides. This is a serious concern that should be addressed promptly.

  1. Symptoms Confirmation: The metallic rattling or buzzing noise, particularly at idle or low RPMs, is a classic symptom of worn timing chain guides. The guides are made of plastic and can become brittle and break over time, leading to slack in the chain. While there might not be an OBD code initially, prolonged driving with a loose chain can lead to more severe issues.

  2. Potential Causes: The primary cause is material degradation of the plastic timing chain guides. Over many heat cycles and miles, these guides can become brittle, crack, and eventually break apart. This allows the timing chain to lose tension and rub against the engine casing, creating the noise you hear.

  3. When to See a Shop: You should see a qualified BMW specialist or mechanic immediately. Continuing to drive with a compromised timing chain can lead to catastrophic engine failure. If the chain jumps a tooth or breaks entirely, it can cause the pistons to collide with the valves, resulting in extensive and very expensive engine damage.

  4. Diagnostics: A skilled technician can often confirm the issue by listening to the engine with a stethoscope, and in some cases, by removing the valve cover for a visual inspection of the top guide. More definitive diagnosis might involve removing the oil pan to inspect for plastic guide fragments or using a borescope. Some shops can also measure timing chain stretch with specialized tools.

  5. Repair: The repair involves replacing the timing chain, guides, tensioner, and often the oil pump chain assembly. This is a labor-intensive job, typically requiring engine removal or significant disassembly. It's crucial to use updated OEM parts for longevity. While it's a significant expense, it's far less costly than a full engine replacement.

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