PROCEDURE WHEN A FUEL INJECTOR BODY IS SEIZED AND CANNOT BE REMOVED BY CONVENTIONAL MEANS

1. Stop the engine and secure the turning gear; isolate the fuel supply to the unit and drain the fuel from the injector/ high-pressure pipe. Tag the unit not-to-run.
2. Remove the high-pressure fuel pipe and the injector's leak-off/ return connections; remove the injector clamping/ holding-down arrangement (clamp, studs, nuts) so the injector is free.
3. Attempt gentle freeing: apply a suitable penetrating oil/ releasing agent (e.g. penetrating fluid) around the injector body/ bore and allow time to soak. Tap the injector body lightly with a soft-faced hammer (never strike the nozzle) to break the corrosion/ carbon bond.
4. Use the injector lifting/ extraction tool: fit the maker's injector puller/ extractor (a threaded puller that grips the injector body and applies a steady axial pull) and apply a controlled pull, rocking gently. Do not use excessive force that could damage the cylinder head bore.
5. If still seized, apply controlled heat: warm the cylinder head bore around the injector (using a hot-air gun/ induction heater or a controlled flame at a safe distance) to expand the head bore relative to the injector, then re-apply the puller. Take care not to overheat or damage the head or the injector.
6. If the injector is still stuck, use a combination of heat and a hydraulic/ mechanical puller, or a slide hammer/ extractor, working progressively. Where the injector is badly seized, it may be necessary to drill/ tap the injector body to fit a puller, or to machine/ cut the injector out (as a last resort, with the head removed) - this is a workshop operation.
7. If all else fails, remove the cylinder head and take it to the workshop where the seized injector can be removed by machining (boring out the injector body) without damaging the head bore; the head bore is then re-machined/ sleeved as required.
8. On removal, inspect the injector bore in the head for scoring, corrosion and damage; clean and, if damaged, re-machine or fit a sleeve/ bush to restore the bore.
9. Refit a new/ overhauled injector with the correct sealing (copper washer/ O-ring), torque the clamp correctly, reconnect the fuel and leak-off lines, and bleed the system.
10. Run the engine and check for fuel leaks and correct injection.

Preventive measures to avoid recurrence

• Use the correct injector seating/ sealing and torque; do not overtighten.
• Ensure the injector is fitted with the correct copper washer/ gasket and that the bore is clean.
• Use the correct fuel quality and maintain the fuel system (filters, heaters) to avoid carbon build-up and corrosion.
• Apply a suitable anti-seize compound to the injector body/ bore at refit (as per maker).
• Follow the maker's injector change interval and use the correct extraction tooling.
• Keep the injector cooling/ leak-off passages clear to prevent overheating and carboning of the injector.