Yes, usually. This is a common repair on many Cummins engines, particularly the 12-valve and 24-valve 5.9L. Because the cups are accessible once the injector is removed, you can replace them with the cylinder head still on the engine.

However, it requires special tools:

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  Cup Puller: A specialized puller (usually a slide hammer with a collet) is used to grip the inside of the old cup and yank it out of the head.

  
  


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  Cup Driver/Installer: A precisely machined tool is needed to drive the new cup in to the exact depth. If the cup is driven in too far or not far enough, the injector won't seat correctly, and it will fail again.

  
  


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  Sealant: The new cup is coated with a specific sealant (like Loctite) before installation to ensure it seals against the coolant jacket.

  
  

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