Camshaft Adjuster Failure (M271)
The M271 supercharged and turbocharged four-cylinder engine uses a camshaft adjuster (variable valve timing gear) that is prone to internal wear and failure. The adjuster is an oil-pressure-operated phasing unit bolted to the end of the camshaft. When internal seals and springs wear, the adjuster loses oil pressure on cold starts, producing a distinctive rattle and eventually causing timing chain problems.
Which models are at risk.
Warning signs to watch for.
Loud rattling or chattering noise for 1-3 seconds on cold startup
Check engine light with camshaft position correlation codes (P0014, P0015)
Rough idle that smooths out after the engine warms up
Reduced power during initial driving after a cold start
Timing chain noise that progressively worsens
Oil consumption increase as the adjuster allows internal oil bypass
Why this happens.
Internal spring and check valve within the camshaft adjuster weaken over time
Oil drains out of the adjuster when the engine is off, causing a momentary loss of hydraulic locking on restart
The timing chain tensioner loses hydraulic pressure simultaneously, allowing chain slack
Extended oil change intervals accelerate wear of the adjuster sealing surfaces
Design limitation — the M271 adjuster was revised multiple times by Mercedes to address this issue
How we diagnose it.
- 01
Listen for the characteristic cold-start rattle — typically lasting 1-5 seconds before oil pressure builds
- 02
Scan for camshaft position fault codes using Star Diagnostic
- 03
Monitor camshaft adjuster angle deviation using the Star Diagnostic live data function
- 04
Remove the valve cover and inspect the timing chain for slack and the tensioner for wear
- 05
Check oil condition and level — low oil or degraded oil worsens the issue
How we fix it.
Replace camshaft adjuster, chain tensioner, and timing chain as a kit
Complete repair addressing all wear items; uses the updated revised adjuster design; long-term fix
Significant labor cost due to front-of-engine disassembly; downtime of 1-2 days
Replace camshaft adjuster only
Lower cost; addresses the primary noise source
Does not address worn chain and tensioner — may need to return for those items later
Used engine replacement
Fresh engine with all components; may be cost-effective if other engine issues exist
Unknown condition of used engine; requires verification that replacement has updated adjuster
Keep it from happening.
Change oil every 7,500 miles maximum with MB 229.51 specification synthetic oil
Use a quality oil filter — MANN or Hengst OE-equivalent
Do not rev the engine hard on cold starts — allow oil pressure to build fully before aggressive driving
If you hear any rattle on cold start, address it promptly before chain wear accelerates
Consider proactive replacement of the adjuster and chain kit at 80,000-100,000 miles
Common questions.
Is the cold start rattle dangerous?
The rattle itself is a symptom, not the danger. The danger is that the worn adjuster allows timing chain slack, which progressively stretches the chain. Eventually the chain can skip a tooth on the sprocket, causing catastrophic valve-to-piston contact. A short rattle (1-2 seconds) is the early stage — if it extends to 5+ seconds or occurs at every start, the repair becomes urgent.
Did Mercedes fix this issue in later M271 engines?
Mercedes revised the camshaft adjuster design multiple times. The latest revision uses a stronger internal spring and improved check valve that better retains oil when the engine is off. When replacing the adjuster, always use the latest superseded part number to get the most current revision.
Can I use thicker oil to reduce the rattle?
Using a slightly thicker oil (such as 5W-40 instead of 5W-30) may reduce the cold-start rattle duration slightly, but it does not fix the worn adjuster. It is a temporary measure at best. The correct repair is adjuster replacement. Using oil outside the Mercedes specification can also cause other issues.
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Learn more →Let’s take care of your Mercedes.
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