Nissan Patrol: TB42E Timing Chain Tensioner Failure

The TB42E 4.2L petrol inline-six uses a hydraulic timing chain tensioner that relies on oil pressure to maintain chain tension. At low oil pressure on cold start, or when oil is degraded, the tensioner collapses momentarily, allowing the chain to slap the timing cover. Over time the tensioner ratchet mechanism wears and fails to hold tension even at operating temperature, causing the chain to jump teeth. A jumped timing chain produces severe valve-to-piston contact, bending valves and sometimes holing pistons. The condition develops gradually and is often ignored until catastrophic failure occurs.

• Loud rattling or chattering noise from front of engine on cold start lasting more than a few seconds
• Rattling present at idle that quiets above 1500 rpm
• Rough running or misfires after high mileage
• Check engine light with camshaft position sensor codes

Cold-start the engine and listen at the front of the engine (timing cover side) for chain slap — a metallic rattling that diminishes as oil pressure builds within 3–5 seconds is borderline; rattle lasting beyond 10 seconds is a failure in progress. Check oil level and condition: low or heavily degraded oil accelerates tensioner wear. Request service history confirming oil change intervals under 7,500 km. If the timing cover has been off, confirm the tensioner, guides, and chain were replaced as a set.

Parts involved: Timing chain.

$1,500 to $6,000 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 the timing chain and tensioner been replaced, and at what odometer reading?”
• “What oil change interval has been maintained throughout the vehicle's life?”

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.