Yanmar 4JH2E injector seats, injector replacement

[markxengineerin]

Attached are some notes that may help someone doing the same job someday, since the Service Manual and Parts Diagram are confusing (if not wrong) for this job, and some questions:

1)What material are the Nozzle Protector and Nozzle Seat? What is the purpose of each part? I am used to diesel injectors that seal with a simple copper washer, not re-useable in theory, but sometimes re-useable in practice.
2) Are these Yanmar parts re-useable, in practice?
3) What is the correct torque specification for the 4JH2E 6mm tie down nuts?
Did Yanmar make a running change to the design of the Nozzle Retainer bracket that is not noted in the Parts Manual, or is the service manual inaccurate?
4) Has anyone else measured new vs. old "tip parts" and can confirm the dimensional changes from new to used?
5) What are the differences between the new and revised injector PN for this engine? How can the injectors not be cross-compatible when they share the same fuel lines, injector pump, cylinder head?

[takis]

The nozzles in old injectors are 155P235J20.
In the new injectors the nozzles are 150P2151CO.

[j.g.evans]

I am not familiar with the part you are trying to remove so this may not help. I have been successful in removing the parts remaining after my injectors were removed by cranking the engine with the starter. Place a towel over the engine to catch the parts.