By RunningRoo Auto Parts — written from the desk of our Product Manager
The Mercedes-Benz M272 and M273 V6 and V8 engines power a long list of popular models, from the C-Class, E-Class and CLK to the GL and ML. They are smooth and capable engines, but their timing chains and camshaft adjusters are a well-documented weak point on higher-mileage cars, producing the classic cold-start rattle. This guide explains the symptoms, the role of the camshaft adjusters and the timing chain kit that fixes it.
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The M272 / M273 timing system
The M272 V6 and M273 V8 use a timing chain that drives the camshafts through hydraulic camshaft adjusters, which provide the variable valve timing. The chain, tensioner, guides and the camshaft adjusters all wear with age, and the adjusters are the most common source of the cold-start rattle as their internal locking pins wear.
Because the engine is an interference design, a stretched chain or a failed tensioner that allows the timing to jump can cause severe valve damage, so a cold-start rattle on these engines should never be ignored.
The symptoms of a failing chain or adjuster
The signature symptom is a rattle from the front of the engine on a cold start that lasts a second or two. A worn chain or adjuster can also cause a rough idle, reduced performance, fault codes for camshaft timing, and, in severe cases, a noisy engine at all times. The table below separates the common causes.
| Symptom | Likely cause | Check |
|---|---|---|
| Cold-start rattle | Camshaft adjuster or tensioner | Isolate the noise |
| Timing correlation codes | Stretched chain | Measure correlation |
| Rough idle, poor power | Adjuster or chain | Scan codes |
| Rattle that persists | Guides or chain | Inspect the timing system |
The camshaft adjuster problem
The M272 and M273 camshaft adjusters use a locking pin that holds the adjuster in position until oil pressure builds. When the pin or its bore wears, the adjuster rattles on start-up and the valve timing drifts. The fix is to replace the worn adjusters, and because the chain and guides are at a similar stage of wear, the job is usually done as a complete timing chain kit with the adjusters.
This is why a “camshaft adjuster rattle” on these engines is almost always a full timing service, not a single-part replacement.
The repair and the right kit
A complete kit for the M272 or M273 should include the timing chain, the tensioner, the guide rails, the sprockets and the camshaft adjusters, plus the seals and fasteners to reseal the engine. On engines with a separate oil-pump or balance-shaft chain, those components are renewed at the same time.
This is a substantial, timing-critical job that requires the correct locking tools, so most owners buy a quality kit and have a Mercedes-specialist workshop fit it.
Which models use the M272 and M273
The M272 V6 and M273 V8 were fitted to a wide range of Mercedes-Benz models through the 2000s and early 2010s, including the C-Class, E-Class, CLK, CLS, S-Class, GL and ML, in both petrol and, for the M272, some markets’ variants. In Australia they are common on the C280, C350, E350, CLK350, GL450 and ML500 among others.
Because the engines span many models and years, the timing chain kit and camshaft adjusters are matched by engine code and VIN, not by the model badge. The M272 and M273 share the same timing system family, which is why the same cold-start rattle diagnosis applies to both.
Balance shaft and oil-pump chains
The M272 and M273 also drive the balance shafts and, on some variants, the oil pump by separate chains, and these chains wear alongside the main timing chain. A complete timing service renews these secondary chains and their tensioners at the same time, because the covers are already off and the labour is already spent.
Skipping the secondary chains to save money is a common mistake that leads to a repeat rattle and a second labour bill, so a complete kit that includes them is the better value.
Preventive maintenance
The M272 and M273 benefit from regular oil changes with the correct specification oil, because the camshaft adjusters and tensioner are oil-actuated and wear faster with dirty or low oil. Addressing a cold-start rattle early is critical on these interference engines, because a jumped chain can cause catastrophic valve damage.
For a high-mileage Mercedes, budgeting for the timing chain, guides and camshaft adjusters at the first sign of a rattle is the cheapest way to protect the engine.
The cost of ignoring the rattle
The M272 and M273 are interference engines, so a cold-start rattle that is ignored can progress from a worn adjuster to a stretched chain and finally to a jumped chain and catastrophic valve damage. The repair bill escalates sharply at each stage — from a timing service to an engine rebuild.
Addressing the rattle at the first sign, while it is still a timing chain and adjuster service, is dramatically cheaper than waiting. The rattle is the engine’s warning, and on these engines it is a warning worth heeding immediately.
Key takeaways
The M272 and M273 cold-start rattle is almost always the camshaft adjusters or the timing chain tensioner, and the correct repair is a complete timing chain kit that includes the adjusters, guides and secondary chains. Because the engines are interference designs, the rattle should be addressed promptly.
For a high-mileage Mercedes, a quality kit matched by engine code and fitted by a specialist is the best value, and it protects an engine that would otherwise risk catastrophic damage.
The complete M272 / M273 timing service
A complete timing service for the M272 or M273 renews the timing chain, the tensioner, the guide rails, the sprockets and the camshaft adjusters, together with the balance-shaft and oil-pump chains where fitted, plus the seals and sealant. This is the complete fix for the cold-start rattle, and it is the best value because the labour is only paid once.
The job requires the correct locking tools and a confident timing procedure, so most owners buy the quality kit and have a Mercedes-specialist workshop carry out the installation. The result is a quiet, correctly timed engine for years to come.
Quick reference: the M272 / M273 timing service
Use this checklist when planning an M272 or M273 timing chain service:
- Address any cold-start rattle immediately, because the engine is an interference design.
- Record the engine code and VIN to confirm the correct kit.
- Renew the chain, tensioner, guides, sprockets and camshaft adjusters together.
- Renew the balance-shaft and oil-pump chains where fitted.
- Use the correct locking tools and torque sequence.
- Turn the engine over by hand before the first start.
A complete service done promptly is the cheapest way to protect these otherwise excellent engines, and it avoids the catastrophic valve damage that a jumped chain causes.
Frequently asked questions
What causes the M272 cold-start rattle?
Usually worn camshaft adjuster locking pins or a tired timing chain tensioner, producing a brief rattle until oil pressure builds.
Is the M272 timing chain a common failure?
The chain, tensioner, guides and camshaft adjusters are a known wear point on higher-mileage M272 and M273 engines.
Should I replace the camshaft adjusters with the chain?
Yes, they are normally renewed together as a complete kit, because the labour is already spent.
Is the M272 an interference engine?
Yes, so a jumped chain can cause severe valve damage and the rattle should be addressed promptly.
How much does an M272 timing chain job cost?
It is a larger job than a four-cylinder, but a quality kit keeps the parts cost reasonable for a Mercedes.
Do the M272 and M273 share the same timing system?
Yes, they use the same chain and camshaft-adjuster design, so the same cold-start rattle diagnosis applies to both.
Should I renew the balance-shaft chain too?
Yes, the secondary chains are renewed as part of a complete timing service, because the labour is already spent.
Why is the M272 cold-start rattle urgent?
Because the engine is an interference design, and a jumped chain can cause catastrophic valve damage if the rattle is ignored.
What does a complete M272 timing service include?
The chain, tensioner, guides, sprockets and camshaft adjusters, plus the secondary chains and seals where fitted.
Do I need the camshaft adjusters even if only the chain is worn?
Yes, they are normally renewed together, because the adjusters and chain wear similarly and the labour is already spent.
Which Mercedes models have the M272 or M273?
The M272 V6 and M273 V8 were fitted widely, including the C-Class, E-Class, CLK, CLS, S-Class, GL and ML models through the 2000s and early 2010s.
How often should the M272 chain be serviced?
There is no fixed interval, but a cold-start rattle means the chain, tensioner and camshaft adjusters should be inspected promptly.
Is the M272 chain service a DIY job?
It is a substantial, timing-critical job, so most owners have a Mercedes specialist carry it out.
Can the M272 timing system be inspected without removal?
The rattle and timing correlation can be checked with a scan tool and by listening, but the chain, guides and adjusters are only fully inspected once the front covers come off.
Is the cold-start rattle always the camshaft adjusters?
Usually, but a tired tensioner or a stretched chain can produce the same noise, which is why the complete timing system is inspected and renewed together.
How do I know if my Mercedes has the M272 or M273?
Check the engine code on the data sticker or have the VIN decoded. Many 3.0–3.5L V6 models use the M272 and 4.6–5.5L V8s use the M273.
Shop the parts mentioned in this guide
- Timing Chain Kit for Mercedes-Benz M272 / M273 E500 / GL450 / Vito / GLK350 / Sprinter
- Timing Chain Kit Full Set with 4x Camshaft VVT Adjusters for Mercedes-Benz M272
- Timing Chain Kit with Oil Pump Drive Chain for Mercedes-Benz M272 / M273 / M276
- Engine Oil Pump Drive Chain Set for Mercedes-Benz M272 / M273 / M276
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RunningRoo Auto Parts – Based in Melbourne, Australia 🇦🇺
📞 Free 24/7 Pickup Available (Contact 0425890125)
💬 Any questions? Message or Call us anytime! We’re here to help.Why Choose RunningRoo?
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Sources and further reading
- Mercedes-Benz M272 engine — Wikipedia
- Timing chain — Wikipedia
- RACV — car maintenance and repair guidance
- CarsGuide — Australian motoring advice
RunningRoo Auto Parts – Based in Melbourne, Australia 🇦🇺
📞 Free 24/7 Pickup Available (Contact 0425890125)
💬 Any questions? Message or Call us anytime! We’re here to help.Why Choose RunningRoo?
✅ Aussie Owned & Operated | 🚚 Fast Shipping | 🤝 Friendly Support