Illustrative guide artwork, not a genuine OEM part photograph.
The 2.7 and 3.0 litre TDV6 diesel engines fitted to the Discovery 3 and 4 use swirl flaps within the inlet manifold to improve combustion efficiency at low engine speeds. Over time, these flaps are known to fail on high-mileage examples.
The plastic swirl flaps can wear, snap, or seize, and in worst cases a broken flap can be ingested into the engine, causing significant damage. More commonly, a stuck or faulty flap simply triggers a fault code and rough running.
Rough idling, a noticeable loss of power, an illuminated engine management light, or the engine going into a protective 'limp' mode can all point to a manifold or swirl flap issue.
Ask whether the inlet manifold has ever been replaced or the swirl flaps removed/blanked — a common preventative fix on higher-mileage cars. A specialist diagnostic check is the most reliable way to confirm the current condition.
We inspect for known TDV6 issues like this on every Discovery we prepare for sale.
What Goes Wrong
The plastic swirl flaps can wear, snap, or seize, and in worst cases a broken flap can be ingested into the engine, causing significant damage. More commonly, a stuck or faulty flap simply triggers a fault code and rough running.
Warning Signs
Rough idling, a noticeable loss of power, an illuminated engine management light, or the engine going into a protective 'limp' mode can all point to a manifold or swirl flap issue.
What to Check
Ask whether the inlet manifold has ever been replaced or the swirl flaps removed/blanked — a common preventative fix on higher-mileage cars. A specialist diagnostic check is the most reliable way to confirm the current condition.
Buying from HMC
We inspect for known TDV6 issues like this on every Discovery we prepare for sale.
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