Nissan Primera: QG18DE timing chain stretch and manual valve clearance adjustment

Two things need knowing about the QG18DE in the P12 Primera. The first is the timing chain: past roughly 160,000 km it stretches, and the car starts jerking and idling roughly as the timing drifts. The second is less famous and matters just as much — this engine has no hydraulic lifters, so the valve clearances need adjusting by hand roughly every 100,000 km. That is a real workshop job that a great many owners have never had done, and skipped adjustments cause a tapping noise at first and burnt valves later. Both faults sound similar from the driver's seat, both are mileage-driven rather than random, and both are the sort of thing where the service history is worth more than the odometer on an imported car.

• Rattle from the front of the engine after a cold start
• Persistent tapping or ticking from the top of the engine once warm
• Jerking, hesitation or a rough idle
• Engine warning light with camshaft or crankshaft timing codes
• Harder starting, or a general loss of smoothness

Listen to it cold and then listen to it warm, because the two faults show at different moments. Be standing at the front when it is started from stone cold and listen to the first few seconds for a rattle or chatter from the front of the engine, which points at the chain. Then let it reach temperature and listen at the top of the engine at idle for a steady tapping or ticking that keeps time with the revs, which points at valve clearances. Watch the tachometer at idle for a needle that will not settle. On the drive, note any jerking or hesitation as you accelerate gently, and watch for an engine warning light. Then ask for the service history and look specifically for a valve clearance adjustment — most cars have never had one, and its absence on a car past 100,000 km is worth pricing in. Ask whether the timing chain has been done. On an import, ask what is actually known about the car's history in Japan. If a workshop inspection is possible: ask for the valve clearances to be measured and the timing codes read.

Parts involved: Timing chain.

$600 to $2,800 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.

• “Have the valve clearances ever been adjusted, and at what mileage?”
• “Has the timing chain ever been replaced?”
• “Does it rattle when cold or tap when warm?”

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.