Nissan Navara: D40 YD25DDTi Head Gasket Failure Between Bores

The YD25DDTi 2.5-litre four-cylinder diesel engine fitted to the D40 Navara has a well-documented failure mode where the head gasket cracks or erodes in the fire ring land between adjacent combustion chambers, particularly between cylinders 3 and 4. The narrow inter-bore bridge on the cast iron block combined with the high combustion pressures from a common-rail turbo diesel creates a hot spot that fatigues the MLS (multi-layer steel) head gasket over time. Symptoms include coolant loss without visible external leak, white exhaust smoke, and combustion gas contamination of the coolant. The failure is accelerated by overheating episodes, cooling system neglect, or high towing loads. Many failures occur between 150,000 and 250,000 km. The aluminium cylinder head also commonly warps and must be resurfaced or replaced.

• White or sweet-smelling smoke from exhaust under load
• Coolant level dropping with no external leak
• Bubbling or pressurisation in the coolant overflow reservoir
• Overheating temperature gauge readings
• Milky or frothy oil on dipstick or under oil cap
• Loss of power or rough idle

1. 1

   Perform a combustion leak (block) test on the coolant reservoir — a positive result confirms exhaust gas in coolant.

2. 2

   Check the oil dipstick and underside of the oil filler cap for mayonnaise-like emulsification.

3. 3

   Inspect exhaust output at idle and under load for sustained white smoke.

4. 4

   Ask for coolant service records and check for any prior head gasket repair receipts.

5. 5

   Check whether the head has been skimmed.

Parts involved: Head gasket.

$2,800 to $5,500 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 head gasket ever been replaced, and is there an invoice from the workshop?”
• “Has the vehicle ever overheated?”
• “When was the coolant last changed and has the level been stable?”
• “Has the cylinder head been inspected or resurfaced?”

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.