Storing and handling injectors without damaging them

A diesel injector is a precision assembly with clearances measured in microns. It is also, unfortunately, robust enough to survive handling that quietly ruins it. Most of the premature failures we are asked to investigate trace back to storage or fitting practice rather than manufacture.

Contamination is the main risk

• Leave an injector uncapped and dust will find the nozzle — particles that would be invisible on a bench are enormous relative to the internal clearances.
• Reuse the protective caps; they exist for a reason and a replacement is cheaper than a replacement injector.
• Never use compressed workshop air to blow dust off an injector; it carries oil and water from the line.
• Keep injectors away from grinding, machining and painting areas.

Corrosion from moisture

Diesel fuel systems tolerate surprisingly little water. An injector stored in a damp environment, or one whose ports have been left open, can develop surface corrosion internally within weeks. The damage is often invisible from outside and presents as erratic operation after fitting.

Store in a dry, temperature-stable location. Do not store injectors in an unheated container outdoors, where condensation cycles occur daily.

Handling the nozzle end

The nozzle tip should never contact a hard surface. Do not stand an injector on its nozzle, and do not allow them to rattle against each other in a box. Ship and store them individually supported, which is how we pack them.

Fitting practice

• Clean the injector bore and the seat in the cylinder head before fitting — debris left in the bore will be trapped against the sealing surface.
• Use new sealing washers and, where specified, new clamp bolts. These are single-use items.
• Torque to specification with a calibrated wrench; over-torquing distorts the body and under-torquing causes compression leakage.
• Do not prime or crank the engine with injectors fitted loosely in an attempt to bleed the system.

If in doubt, ask

If a unit has been stored for a long period, or you are unsure of its condition before fitting, send it to be tested rather than fitting it and hoping. A flow test costs far less than the labour of removing a faulty injector twice.