Mercedes-Benz C-Class: M271 Camshaft Adjuster Seal and Rocker Cover Gasket Oil Leaks

The M271 engine commonly develops oil leaks from two principal locations: the variable camshaft timing adjuster seals on the front of the cylinder head, and the rocker/cam cover gasket running along the top of the head. Both seals are made of rubber that hardens and shrinks with age and heat cycling. Oil from the adjuster seals runs down the front of the engine and can contaminate the serpentine belt and pulleys, while rocker cover leaks pool oil at the rear of the cam cover and can drip onto hot exhaust components. Both faults are widely documented across W203 C200/C200K and W204 C180/C200/C250 models.

• Oil burning smell from engine bay particularly after shutdown
• Visible oil staining on front of engine or around cam cover
• Oil pooling under the vehicle after parking
• Serpentine belt or alternator contaminated with oil

1. 1

   With engine off, inspect the front of the cylinder head for oil seepage around the two camshaft VVT adjuster bolts.

2. 2

   Inspect the top of the engine along the full length of the rocker cover for wet or dried oil residue.

3. 3

   Check the serpentine belt for oil contamination which indicates adjuster seal failure.

4. 4

   Look under the vehicle for fresh oil drips directly below the engine.

Parts involved: Rocker / valve cover.

$400 to $1,200 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, 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.

• “Has the rocker cover gasket or camshaft adjuster seals been replaced?”
• “Has any oil burning smell been noticed after driving?”
• “Is there any oil visible under the vehicle when parked?”

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.