Mercedes-Benz G-Klasse W463a

Modern inline-six diesel with aluminium block and steel pistons — technically the highest-quality diesel in the current Mercedes line-up. The vacuum-controlled coolant pump was subject to a recall (action code 2090008) due to fire risk from coolant entering the vacuum circuit. Piezo injectors sensitive to water-contaminated or low-quality diesel (CP4 fuel pump). Camtronic actuators require regular maintenance. DPF clogging on pure city use. Regular motorway driving recommended as maintenance.

• !! Recall Coolant Pump — Fire Hazard (Action Code 2090008)

  The vacuum-controlled coolant pump can develop leaks between the coolant and vacuum circuits. Coolant enters the EGR solenoid valves; an electrochemical reaction creates a fire hazard.

  0–0 $
  Ad coolant pump OM656Unterdruckventil OM656Aktionscode 2090008
• !! Bosch CP4 Pump Sensitive to Fuel Quality from 120,000 km

  The Bosch CP4 high-pressure pump is more sensitive to fuel contamination than its predecessors. Poor diesel quality can damage the pump and injectors.

  Symptoms: Power loss, hesitation, injection system fault codes, in severe cases engine damage from metal swarf
  1,500–6,000 $
  Ad high-pressure fuel pump OM656Bosch CP4-high-pressure fuel pump OM656fuel filter OM656
• !! Rocker Arms Prematurely Worn — Camshaft Damage from 100,000 km

  Early OM656 units had overly soft roller rocker arms. From engine number 80278367 (10/07/2018) a reinforced version was fitted. Older engines develop camshaft wear and timing chain problems.

  Symptoms: Clattering tick in the valvetrain, especially on cold start, increased oil consumption, CEL, rough running
  2,000–6,000 $
  Ad Rocker Arm OM656 A6540505701Roller Rocker Arm R6 Diesel S-ClassCamshaft OM656 A6560501000

+ 2 more engine weaknesses + vehicle weaknesses

Modern inline-six diesel with aluminium block and steel pistons — technically the highest-quality diesel in the current Mercedes line-up. The vacuum-controlled coolant pump was subject to a recall (action code 2090008) due to fire risk from coolant entering the vacuum circuit. Piezo injectors sensitive to water-contaminated or low-quality diesel (CP4 fuel pump). Camtronic actuators require regular maintenance. DPF clogging on pure city use. Regular motorway driving recommended as maintenance.

• !! Recall Coolant Pump — Fire Hazard (Action Code 2090008)

  The vacuum-controlled coolant pump can develop leaks between the coolant and vacuum circuits. Coolant enters the EGR solenoid valves; an electrochemical reaction creates a fire hazard.

  0–0 $
  Ad coolant pump OM656Unterdruckventil OM656Aktionscode 2090008
• !! Bosch CP4 Pump Sensitive to Fuel Quality from 120,000 km

  The Bosch CP4 high-pressure pump is more sensitive to fuel contamination than its predecessors. Poor diesel quality can damage the pump and injectors.

  Symptoms: Power loss, hesitation, injection system fault codes, in severe cases engine damage from metal swarf
  1,500–6,000 $
  Ad high-pressure fuel pump OM656Bosch CP4-high-pressure fuel pump OM656fuel filter OM656
• !! Rocker Arms Prematurely Worn — Camshaft Damage from 100,000 km

  Early OM656 units had overly soft roller rocker arms. From engine number 80278367 (10/07/2018) a reinforced version was fitted. Older engines develop camshaft wear and timing chain problems.

  Symptoms: Clattering tick in the valvetrain, especially on cold start, increased oil consumption, CEL, rough running
  2,000–6,000 $
  Ad Rocker Arm OM656 A6540505701Roller Rocker Arm R6 Diesel S-ClassCamshaft OM656 A6560501000

+ 2 more engine weaknesses + vehicle weaknesses

Modern inline-six diesel with aluminium block and steel pistons — technically the highest-quality diesel in the current Mercedes line-up. The vacuum-controlled coolant pump was subject to a recall (action code 2090008) due to fire risk from coolant entering the vacuum circuit. Piezo injectors sensitive to water-contaminated or low-quality diesel (CP4 fuel pump). Camtronic actuators require regular maintenance. DPF clogging on pure city use. Regular motorway driving recommended as maintenance.

• !! Recall Coolant Pump — Fire Hazard (Action Code 2090008)

  The vacuum-controlled coolant pump can develop leaks between the coolant and vacuum circuits. Coolant enters the EGR solenoid valves; an electrochemical reaction creates a fire hazard.

  0–0 $
  Ad coolant pump OM656Unterdruckventil OM656Aktionscode 2090008
• !! Bosch CP4 Pump Sensitive to Fuel Quality from 120,000 km

  The Bosch CP4 high-pressure pump is more sensitive to fuel contamination than its predecessors. Poor diesel quality can damage the pump and injectors.

  Symptoms: Power loss, hesitation, injection system fault codes, in severe cases engine damage from metal swarf
  1,500–6,000 $
  Ad high-pressure fuel pump OM656Bosch CP4-high-pressure fuel pump OM656fuel filter OM656
• !! Rocker Arms Prematurely Worn — Camshaft Damage from 100,000 km

  Early OM656 units had overly soft roller rocker arms. From engine number 80278367 (10/07/2018) a reinforced version was fitted. Older engines develop camshaft wear and timing chain problems.

  Symptoms: Clattering tick in the valvetrain, especially on cold start, increased oil consumption, CEL, rough running
  2,000–6,000 $
  Ad Rocker Arm OM656 A6540505701Roller Rocker Arm R6 Diesel S-ClassCamshaft OM656 A6560501000

+ 2 more engine weaknesses + vehicle weaknesses

The M177 is AMG's most widely used V8 biturbo today and is considered technically mature and long-lived. The hot-V turbocharger arrangement delivers spontaneous response with barely perceptible lag. Weaknesses are manageable: wastegate rattle in cold weather, ignition coil recall for early 2015 model years, valve cover gaskets with age. Regular oil changes with attention to oil quality deliver a very robust engine. In direct comparison with the M156 less emotional, but significantly more reliable and efficient.

• !! MCT Gearbox — Clutch Wears in City Traffic from 60,000 km

  The MCT Speedshift gearbox (wet launch clutch instead of torque converter) wears the clutch significantly faster in frequent stop-and-go. Clutch replacement requires gearbox removal.

  Symptoms: Judder on pull-away, clutch slip at full load, gearbox warning message, delayed engagement from standstill
  3,000–6,000 $
  Ad MCT clutch AMG C63 W205Speedshift MCT clutch kitA2052500200 MCT clutch
• !! Camshaft Adjuster Solenoid Draws Oil into Wiring Harness from 70,000 km

  Identical issue to the M176/M278: the solenoid leaks, oil migrates by capillary action through the wiring harness. On AMG vehicles this is even more frequent due to higher oil temperatures.

  Symptoms: Cold-start rattle, camshaft adjuster fault code, oil traces on connector, potential ECU consequential damage
  500–3,000 $
  Ad Camshaft adjuster M177 AMGOil stop ring M177 wiring harnessA1779050100 solenoid
• !! Timing chain guide failure from 100,000 km

  At higher mileage the plastic timing chain guide rails can fracture. Debris enters the oil sump and can cause secondary damage. Repair costs €4,000–8,000.

  Symptoms: Tek-tek-tek noise on cold start that disappears after a few minutes. Later: extended start times, knocking from engine bay
  4,000–8,000 $

+ 6 more engine weaknesses + vehicle weaknesses

4.0-litre V8 with two turbochargers in the cylinder valley — the so-called hot-inside-V arrangement keeps the exhaust paths short and virtually eliminates turbo lag. The M176 is the civilian variant of the AMG V8: same basic architecture, different mapping, not a hand-built individual unit. Water-cooled charge air coolers in the cylinder valley reduce intake charge temperature from over 140°C to near ambient. Cylinder deactivation silences four cylinders at part-load — only perceptible as minimal steering wheel vibration. Maintenance note: do not push oil change intervals, as the oil separator in the crankcase breather reacts badly to old oil and, when blocked, pushes out the valve cover gasket — extensive front-end disassembly required. Change spark plugs every 80,000 km, plan intake valve carbon cleaning after 70,000 km. When buying used, listen for wastegate rattle at part-load — addressable via Xentry. Check camshaft adjuster solenoids for oil traces at the connector.

• !! Timing Chain Stretch — M176 4.0L V8 from 120,000 km

  The timing chains on the M176 V8 can stretch at high mileage. Due to the hot-inside-V design the repair is very complex as the turbochargers sit between the cylinder banks.

  Symptoms: Chain rattling on cold start, camshaft fault codes, rough idle
  4,000–10,000 $
  Ad Timing chain M176Chain tensioner 4.0 V8 BiTurbo
• !! Camshaft Adjuster Solenoid Draws Oil into Wiring Harness from 80,000 km

  The camshaft adjuster solenoid on the M176 leaks and oil migrates by capillary action through the wiring harness to the ECU. A known Mercedes V8 issue since the M278.

  Symptoms: Cold-start rattle for 1–2 seconds, camshaft adjuster fault code, oil traces on connector, in extreme cases ECU failure
  400–2,500 $
  Ad Camshaft adjuster M176 solenoidOil stop ring M176 wiring harnessA2769050200 camshaft solenoid
• !! Coolant Pump Leaking from 80,000 km

  The coolant pump on the M176 can develop a leak at the seal. Coolant loss leads to engine overheating if not addressed.

  Symptoms: Coolant level drops, coolant puddle under the vehicle, temperature gauge rises
  400–1,200 $
  Ad Coolant pump M176Water pump M176 4.0 V8

+ 6 more engine weaknesses + vehicle weaknesses