Ford Courier: WL 2.5D Injector Seat O-Ring External Fuel Leak

The WL 2.5 diesel seals each injector into the head with a small O-ring. The rings harden with age and heat and start to weep, so diesel escapes past the injector and runs down the back of the engine. It rarely stops the car, which is why it is usually left: the owner smells fuel, tops up slightly more often, and carries on. Left alone the leak washes oil off the block, soaks the loom and becomes a fire risk near a hot turbo. The parts are inexpensive; the labour is the cost, and doing all four at once is far cheaper than doing them one at a time.

• Diesel smell around the engine bay after a run
• Wet, dirty film down the back of the engine or on the bulkhead
• A faint tick or puff from the top of the engine when cold
• Fuel use creeping up with no change in driving

1. 1

   Open the bonnet after a decent drive and look along the top of the engine where the injectors enter the head — a weeping seal leaves a dark wet trail.

2. 2

   Check the bulkhead behind the engine for diesel staining.

3. 3

   Ask whether the injectors have ever been out and whether the seals were replaced when they were.

Parts involved: Fuel injector.

$400 to $1,200 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 injectors ever been removed or reseated?”
• “Is there a diesel smell after driving it?”
• “When were the injector seals last replaced?”

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.