Nissan Patrol: TD42 Bosch VE Injection Pump Wear and Timing Drift

The TD42 4.2L naturally aspirated diesel uses a Bosch VE rotary injection pump. The internal metering valve and governor weights wear over high mileage, causing injection timing to retard and fuel delivery to become uneven across cylinders. Retarded timing produces excessive black smoke, hard starting when cold, and a characteristic 'clatter' at idle. The advance mechanism driven by engine oil pressure also wears, making cold-start timing unpredictable. Rebuilding requires specialist diesel injection equipment; replacement pumps are increasingly difficult to source new. The lift pump (mechanical, camshaft-driven) is also a wear item that causes vapour lock and hard starting when diaphragm fails.

• Black smoke at idle and under load disproportionate to engine condition
• Hard cold starting requiring extended cranking
• Uneven idle with a pronounced knock or rattle
• Fuel leaking from the pump inspection plate or overflow union

1. 1

   Request a diesel injection pump timing check with a dial gauge on the pump delivery port — correct static timing is 8 degrees BTDC for naturally aspirated TD42.

2. 2

   Observe cold start: excessive black smoke on a well-maintained engine indicates timing retard.

3. 3

   Inspect the pump body for fuel weeping at the inspection cover and around the drive shaft seal.

4. 4

   Check lift pump operation by cracking the inlet union — weak or no fuel flow under cranking indicates diaphragm failure.

5. 5

   Ask for service history showing pump calibration.

Parts involved: High-pressure fuel pump.

$800 to $3,500 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 injection pump been serviced, recalibrated, or replaced, and by which diesel specialist?”
• “Does the vehicle start reliably in cold temperatures below 5 degrees Celsius?”

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.