Land Rover Range Rover: Plastic inlet manifold cracking — 'Restricted Performance' on the 3.0 diesel

The inlet manifold on the 3.0 TDV6 and SDV6 is a plastic part, and it cracks. So do the rocker covers on the same engines. The result is an unmetered air leak, and the first the driver knows about it is a 'Restricted Performance' message and the car dropping into a reduced-power mode, most often when the engine is loaded — pulling up a hill, overtaking, or towing. It can be intermittent for weeks before it becomes permanent, which is why a short flat test drive can miss it entirely. The same message has several possible causes on this engine, including a leaking gasket and a failing throttle body, so a driver reporting 'Restricted Performance' has told you there is a problem but not which one. It is a genuine repair rather than a catastrophe, but it is not a small one, and a car being sold with the message appearing occasionally is a car being sold for a reason.

• 'Restricted Performance' message with a sudden loss of power
• Power returning to normal after switching the engine off and on
• Hissing or whistling from the top of the engine under load
• Engine warning light, sometimes clearing by itself
• Rough idle, or hesitation when accelerating hard

1. 1

   Load the engine on the test drive, because this fault hides at light throttle.

2. 2

   Find a hill or a motorway on-ramp and accelerate hard through it, then repeat — a 'Restricted Performance' message and a sudden flattening of power is the classic presentation, and it very often takes more than one hard pull to bring on.

3. 3

   Watch the whole dash during those pulls rather than just the road.

4. 4

   With the bonnet up and the engine idling, listen across the top of the engine for a hiss or a whistle that rises with the revs.

5. 5

   Look over the plastic inlet manifold and rocker covers for obvious cracks, oil weeping along a seam, or a section that has been sealed or repaired.

6. 6

   Ask the seller directly whether the car has ever shown a 'Restricted Performance' message and what was done about it — most owners of these have seen it at least once and will say so.

7. 7

   Check the service record for manifold, rocker cover or throttle body work.

8. 8

   If a workshop inspection is possible: have the stored fault codes read, since manifold cracks, gasket leaks and throttle body faults all trigger the same message and carry very different bills.

Parts involved: Intake manifold.

$700 to $2,600 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 a 'Restricted Performance' message ever appeared, and how often?”
• “Has the inlet manifold, rocker cover or throttle body ever been replaced?”
• “Does it ever lose power going up a hill or when overtaking?”

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.