The Critical Importance Of Cleanliness When Installing Injectors

The Critical Importance Of Cleanliness When Installing Injectors

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 Installing Injectors

Though it may come as a surprise, the internal tolerance of a common rail injector is remarkably small. A micrometer (micron) is effectively a thousandth of a millimeter. The internal net clearance of many of the injector components is 5 microns. This means there’s only 2 ½ microns of clearance by the side of the moving and stationary component.

Even things like the air gap or the lift profile of the injector is commonly around 50 microns of total lift, with an average tolerance of 1 or 2 microns. So it shows the absolute tolerances of which common rail injectors particularly are manufactured to. It also highlights the complete necessity to be incredibly thorough and clean when you install the injectors.

In many instances we’re changing injectors in cars that are 200,000 to 300,000 KM old, and even a small dust particle could create significant issues. So it’s important that we do our absolute best to make sure that it’s as clean as possible. In doing so, we minimize the potential for contamination and seizure related or missing related failures after installation. Taking additional care when ‘opening’ the fuel system of a Common Rail Equipped vehicle usually consists of:

  • Washing down the engine bay before you begin
  • Ensuring that you’ve cleaned or isolated the material that may be on the under side of the bonnet
  • Having adequate blanking caps to close off the rail. This will significantly reduce the exposure time to atmosphere and therefore reduce the risk
  • Ensure that if you’re going to use compressed air, that it is adequately filtered (most only filter to 20 microns).
  • And so on.

As you can see, the tiny tolerances that we play with (AND the significant cost of the components) means that its worth spending a little extra time to ensure that its done once, done right.

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