Mazda 5 CW

The 1.6 CD is the bought-in Ford/PSA diesel of the DV series (DV6) — the most notorious of the family. The signature failure is the turbocharger from oil starvation: the screen in the lower banjo bolt of the oil line clogs with carbon and the turbo runs dry — many shops remove the screen preventively. Even more expensive is the high-pressure pump, which self-destructs and sends metal swarf through the entire fuel system — often an economic write-off. Add DPF clogging, sticking EGR valves, leaking injectors and seized glow plugs. Only recommendable with meticulous maintenance, short oil intervals and a long-distance profile.

• !! Turbocharger Damage from Insufficient Oil Supply from 120,000 km

  Soot deposits block the oil supply to the turbo radial bearing. The structurally tight oil quantity (380 instead of 500 ml/min) accelerates wear. A short cool-down period after hard driving helps.

  Symptoms: Whistling noise from turbo, power drop, limp mode, exhaust smoke
  800–2,500 $
  Ad turbocharger DV6TED4turbocharger Mazda 3 1.6 CD
• !! High-Pressure Pump Generating Metal Particles from 150,000 km

  The high-pressure pump metering valve fails and the pump seizes. Metal particles reach all injectors — total failure of the injection system. The entire system must be replaced.

  Symptoms: Engine won't start, all injectors failed simultaneously, power drop to zero
  1,500–5,000 $
  Ad High-pressure pump DV6TED4Metering valve 1.6 HDI PSA
• !! Diesel Particulate Filter Blocked from 120,000 km

  The DPF does not fully regenerate with short-trip driving. Eolys additive must be topped up every 60,000 km. A clogged DPF also stresses the turbocharger through increased exhaust backpressure.

  Symptoms: DPF warning light, power loss, elevated consumption, limp mode
  500–2,000 $
  Ad Particulate filter DV6TED4DPF Mazda 3 BK 1.6 CDEolys additive Mazda

+ 3 more engine weaknesses + vehicle weaknesses

The 1.8 MZR is a chain-driven naturally aspirated petrol of the Ford Duratec family — robust, but with two more serious topics. First, oil consumption rises at higher mileage from worn piston rings; replacing only the valve stem seals barely helps. Second, the brittle plastic levers of the intake-manifold swirl flaps break — a detached flap can be ingested. The timing chain stretches only late (no timing belt!). Add the usual age items such as throttle fouling and lazy sensors. Keep an eye on the oil level and it is a durable engine.

• !! Timing chain stretches (no timing belt) from 120,000 km

  The MZR is chain-driven — the earlier assumption of a timing belt is wrong. With mileage the chain stretches and the tensioner and guides wear; it rattles on cold start and at low rpm. Replace chain, guides and tensioner as a set.

  Symptoms: Rattle on cold start and below about 2,000 rpm, noise from the front timing case.
  450–800 $
  Ad Mazda 1.8 MZR timing chain kitMazda L8 timing chain
• !! Swirl flaps / intake-manifold lever break from 90,000 km

  The brittle plastic lever between the vacuum actuator and the swirl-flap shaft usually breaks after years. A detached flap can be ingested and, in the worst case, cause engine damage. Metal repair kits are cheap; a full manifold replacement is expensive.

  Symptoms: Rattle/clatter from the intake manifold, poor throttle response below about 40 km/h, slightly raised consumption.
  60–600 $
  Ad Mazda MZR swirl flap repair kitMazda 3 6 MZR intake manifold
• !! High oil consumption from piston rings from 150,000 km

  At higher mileage the oil control rings stick or wear and the engine burns increasing amounts of oil (sometimes a litre over a few hundred to a thousand km). Replacing only the valve stem seals barely helps — the rings are the cause. The only fix is stripping the engine.

  Symptoms: Dropping oil level between services, blue smoke under load, no external leak.
  2,000–2,500 $
  Ad Mazda MZR piston ringsMazda petrol engine rebuild

+ 4 more engine weaknesses + vehicle weaknesses

2.0 litre MZR, 160 hp — rougher and more characterful than the NB engines, more displacement, more torque. Not the sharp wail of the NA 1.6, but a broader growl. The NC-specific engine problem: sudden oil loss from coked 5W-30 at cylinder 4, especially NC1 (2005-2009). Fix: switch to 5W-50 after warranty and check oil level obsessively. VVT solenoid gets contaminated at high mileage. NC2/NC3 (from 2009) with revised internals are considerably more reliable. Buying an NC? NC2 or NC3. The NC was mocked as the Fat Miata — unfairly on a country road, fairly on the scales.

• !! Throttle body dirty from carbon deposits from 80,000 km

  Carbon deposits on the throttle ring cause a sticky mechanism and unstable idle. Particularly common on the Mazda6 GG — engine stalls on declutching.

  Symptoms: Engine dies when declutching or braking, hunting idle, throttle slightly sticky
  50–250 $
  Ad throttle body LF-DE Mazda6 GGthrottle bodyngehäuse 2.0 MZR Mazda 6
• !! Thermostat failure — overheating or under-cooling from 100,000 km

  The thermostat of the LF-DE can fail from around 100,000 km — either sticking closed (overheating) or permanently open (under-cooling). Water pump often follows shortly after.

  Symptoms: Coolant temperature rises sharply or stays permanently low, heater produces no warmth
  80–300 $
  Ad thermostat LF-DE MZR Mazda6 GGwater pump LF-DE Mazda5
• !! VVT solenoid stuck — flat spot at 2,000 rpm from 100,000 km

  The VVT solenoid (oil control valve/OCV) of the LF-DE gums up with oil sludge and prevents variable valve timing. The inlet cam cannot advance. Typical symptom: flat spot around 2,000 rpm. Cleaning or replacing the OCV and regular oil changes as prevention.

  Symptoms: Flat spot when accelerating around 2,000 rpm, rough idle, slight mid-range power loss, occasional check engine light
  80–300 $
  Ad VVT Solenoid OCV LF-DE Mazda MX-5 NCoil control valve camshaft Mazda 2.0 MZR

+ 6 more engine weaknesses + vehicle weaknesses