Mercedes-Benz GLC: M264 timing chain tensioner cold-start rattle

The M264 2.0T engine uses a hydraulic timing chain tensioner that relies on residual oil pressure to maintain chain tension on cold starts. Oil drain-back in the tensioner bore after shutdown allows momentary chain slack when the engine is first cranked in cold conditions. This produces a characteristic metallic rattle from the front of the engine lasting two to fifteen seconds until oil pressure is re-established. Repeated slack events accelerate wear on the plastic chain guide rails; when a guide fractures, chain jump and valve-to-piston contact become possible. The fault is documented across multiple M264 applications including A-Class, C-Class, and GLC from build dates late 2018 onward.

• Metallic rattling from engine front on cold start, disappears within 5-15 seconds
• Check engine light with camshaft position/timing correlation codes P0008 or P0016
• Rough idle briefly after cold start
• In advanced cases, persistent rattle at operating temperature indicating guide failure

1. 1

   Start engine from fully cold soak and listen for timing chain rattle at front of engine near cam cover.

2. 2

   Scan for P0008, P0016, P0017 codes.

3. 3

   Remove oil filler cap and inspect for sludge indicating maintenance neglect.

4. 4

   Check service history for oil change intervals - extended intervals accelerate wear.

5. 5

   If a workshop inspection is possible: Borescope chain area via oil filler if rattles are severe.

Parts involved: Timing chain.

$3,200 to $6,500 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 timing chain or tensioner ever been inspected or replaced?”
• “Can you show full documented service history with oil change intervals?”
• “Has the engine ever produced a cold-start rattle sound from the front of the motor?”
• “What engine oil specification and brand has been used throughout ownership?”

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.