Nissan Patrol: TB42 petrol head gasket failure

The 4.2L TB42 petrol engine is prone to head gasket failure, particularly when coolant maintenance has been neglected or the engine has overheated. The cast-iron block and alloy head combination is susceptible to warping after overheating events. Once the gasket fails, combustion gases enter the coolant or oil, accelerating engine damage. A common pattern in Australian Y60 Patrols with high mileage or unknown service history.

• White smoke from exhaust on startup or under load
• Coolant loss with no visible external leak
• Milky or frothy oil on dipstick or oil cap
• Overheating gauge readings climbing at highway speeds
• Bubbling in coolant overflow reservoir

1. 1

   Check oil filler cap and dipstick for white emulsion.

2. 2

   Observe exhaust for sustained white smoke.

3. 3

   Check coolant for oily film or bubbles.

4. 4

   Request compression or leak-down test across all cylinders.

5. 5

   If a workshop inspection is possible: Pressure-test the cooling system cold and inspect for pressure loss.

Parts involved: Head gasket.

≈A$2,020 to ≈A$4,140 at independent workshop rates, shown as an approximate guide in Australian dollars. That is for this job on its own, not for the car.

An estimate, converted to Australian dollars, 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 engine ever overheated? Has the temperature gauge ever gone into the red?”
• “When were the coolant and thermostat last replaced?”
• “Has the head gasket been replaced previously, and is there documentation?”
• “Has a compression or leak-down test been done recently?”

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.