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.

[Inuit32]

This question is for markxengineerin or any user who really knows. I am currently installing injector on 4JH2E. engine. I look at your pdf document and i am not sure if you are explaining what to do or what Not to do....

The question is: what is the correct order for the copper washer and the heat shield?

Do you install the washer on the tip of the injector first then the heat shield. In other words does the copper washer is sandwich between the injector and the heat shield?

Sorry for my bad English

Thank you for your help

Regards

Inuit32

[skipperpete]

Take another look at the pdf in the first post, the pictures make it perfectly clear, including the washer (not copper) interestingly the photo shows the parts for the 4TNE engine, not the 4JH, the industrial version differs from the marine version in some respects.

[Captain Bill]

Questions;
1: The Nozzle protector is made of Teflon. The seat is some sort of metal but I don't know what specifically. According to the parts manual these are the same parts regardless of what injectors your engine uses.



2: the seats appear to be reusable, but compared to the costs of the remainder of the components they are a very small part of an injector service.



3. My book says .7 to .9 KGt-m which translates to 5 to 6.5 ftlb.


4. The teflon protector bottoms out against a "shelf" which is part of the head and gets squeezed between the injector and the shelf as the retainer is torqued down which does distort the protector. I don't recall the exact measurements but I do recall they were different than the new nozzles at my last service.



5. It is not terribly clear from the drawings provided, but the retainer of the newer type on the left is angled and the flats on the injector where it passes through the retainer is angled to match. You can see the retainer on the right has the flats parallel to the longitudinal axis of the engine. I was once shipped the wrong injectors for my engine (I have the retainer type in the left illustration) and they definitely did not work in my engine. There may be other differences internally, but the difference in the injector and retainer make them not interchangeable.