Yanmar engines 20 hp engine in john deere tractor makes loud clacking noise

Question edited for clarity.
Question moved from Cars and Trucks.

Free Service manual and the specs
https://www.yanmar.com/media/id/com/maintenance/catalog/100495.pdf


https://www.google.com/search?q=Yanmar+tf90-m+head+bolt+torque+spec

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Question edited for a lot more clarity.
Question moved from Cars and Trucks to make model category.

Gator Diesel service manual Page 59

https://radionerds.com/images/4/4e/Technical_Manual_for_the_M-GATOR%281%29.pdf

https://www.google.com/search?q=John+Deere+Gator+6x4+with+Yanmar+Diesel+engine%2C+head+bolt+torque&

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Probably not

If you want to solve your problem, click on the link I attach.
Best Manuals

Visit the on-line store, know as reliable-store, they have the repair manuals. I'm sure you will get the solution of your problem.
Best Manuals

I am not sure what you are calling gunk but if this gunk is black it is engine oil. The tractor and the engine was built by Yanmar. The injection pump is lubricated with oil pressure from the engine. The seals in the pump will leak and engine oil will get in the fuel system and contaminate the diesel fuel and plug the fuel. Seals will have to be replaced in the injection pump to correct the gunk.

Sounds stuffed to me,dump it

engine starving for fuel 1 st change fuel filter then check fuel pump then ck injector pump pressure (caution high pressure)

I found the tech manual one lin but it can"t be opened since deere is updating it.I will see if we have the book"tm1974" at the dealership in the morning and get back to you.