MajorCommonFluid Leaks

Mercedes-Benz CLS: Upper timing cover and camshaft cover oil leaks (M276 3.5 V6, CLS350)

Upper timing cover and camshaft cover oil leaks (M276 3.5 V6, CLS350) is a common fluid leaks fault on the Mercedes-Benz CLS on the 2011–2017 cars, and we rate it major. Putting it right costs ≈A$830 to ≈A$2,580 at independent workshop rates, shown as an approximate guide in Australian dollars. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 5 documented faults on the Mercedes-Benz CLS.

Vehicle: Mercedes-Benz CLS
Engine: 3.5L
Years: 2011–2017
Fuel: petrol
System: Fluid Leaks

This page covers the Mercedes-Benz CLS as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All Mercedes-Benz CLS faults5 documented faults on this model

What you are looking at

No photograph available

We do not hold a verified photograph of the Timing chain yet. We would rather show none than show a picture of a different part.

What goes wrong

The M276 3.5 V6 has no gaskets on its upper front timing covers and camshaft magnet covers, only factory sealant, and that sealant hardens and lets go with heat cycles, often well before high mileage. Oil runs down the front of the engine, can soak the auxiliary drive belt and drip onto the exhaust, and can wick into nearby sensor connectors and set fault codes. The fix is a strip, clean and reseal of the covers (Mercedes issued a service bulletin covering these leaks), and it is best done alongside any timing chain tensioner work because the same covers come off.

What you would notice

Burning oil smell after a drive
Oil residue down the front of the engine or on the lower engine cover
Oil level dropping between services
Squealing or slipping auxiliary belt from oil contamination

How to check it

Where to look. Front top of the engine: upper timing covers and camshaft magnet covers at the front of both cylinder heads

With the bonnet open, use a phone torch to look at the top front corners of the engine where the timing covers meet the cylinder heads, and at the round camshaft magnet covers on the front of each head: wet, dark oil or dust caked in oil is a leak. Look down past the front of the engine at the belt and pulleys for an oily film. After the test drive, sniff for burning oil and look for light smoke from the engine bay. Check the dipstick level or the oil level reading in the instrument cluster and ask how much oil is added between services. If a workshop inspection is possible: on a hoist, check the lower front of the engine and the undertray for oil trails and confirm whether it is the timing covers, the cam covers or the oil cooler seal in the engine valley.

Parts involved: Timing chain.

What it costs to put right

≈A$830 to ≈A$2,580 at independent workshop rates, shown as an approximate guide in Australian dollars. That is for this job on its own, not for the car.

An estimate, converted to Australian dollars, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

“Has the engine had any oil leaks resealed, and which covers were done?”
“How much oil does it need topping up between services?”
“Have you ever smelled burning oil after a drive?”

Now check the Mercedes-Benz CLS you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car still has money owing on it, has been written off or reported stolen, what kms it showed in past sale ads, whether it has had accident repair claims and what it is worth today. That comes from the official records for that plate. Enter the plate and its state for the A$17.90 Vehicle Check, or the full history from A$24.99.

Where this comes from

The failure described above is documented in the sources below. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them.

Motronix: Mercedes Timing Cover Leaks (M272, M273, M276)
603 M-Tech: Common Issues of the Mercedes-Benz M276 Engine (front upper timing cover leaks)
MBWorld forum thread: Timing Cover Leak (W212 E350 M276)
BenzWorld forum thread: Mercedes E350 Oil leak (Cam Covers)

Mercedes-Benz CLS buyer questions

Is upper timing cover and camshaft cover oil leaks (m276 3.5 v6, cls350) serious on a Mercedes-Benz CLS?

We rate it major and common on the Mercedes-Benz CLS. The M276 3.5 V6 has no gaskets on its upper front timing covers and camshaft magnet covers, only factory sealant, and that sealant hardens and lets go with heat cycles, often well before high mileage. Oil runs down the front of the engine, can soak the auxiliary drive belt and drip onto the exhaust, and can wick into nearby sensor connectors and set fault codes. The fix is a strip, clean and reseal of the covers (Mercedes issued a service bulletin covering these leaks), and it is best done alongside any timing chain tensioner work because the same covers come off.

How much does it cost to fix on a Mercedes-Benz CLS?

≈A$830 to ≈A$2,580 at independent workshop rates, shown as an approximate guide in Australian dollars. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which Mercedes-Benz CLS years are affected?

Our research records this fault on the 2011–2017 Mercedes-Benz CLS. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.