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Metric bolts have a different standard than SAE bolts that are grade 8, and 5 on most engine bolts. Metric bolts are graded by “Class”. A class 10.9 is what I have seen in sprinter engines for the injectors. A new copper seal should always be used when the injectors are replaced. The class 10.9 is very close to the SAE grade 8. The minimum tensile strength for a class 10.9 is 1040 Mpa, about 150,000 PSI. If you have any more questions, as always, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
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The hold down bolt is app. 3/16" Are you telling me that a 3/16 bolt has a tensiel strength of 150,000 psi? If not please help me with the math. I have a court date in small claims court for Tuesday. The other guy is trying to say my cylinder pressure was so high that it broke the hold down bolt. How could that be if the tensiel strength is 150,000 psi? The cylinder pressure should never go that high. Please, I need your help. Jerry
I think you missed a major point, and that is pounds per square inch, the bolt is nowhere near one square inch, so it wont have 150000 pounds of tensile strength, that one square inch has. Calculate PI x the bolt radius squared, and multiply it times the tensile strength, to get the actual strength of the bolt, It needs to either be done in inches, or all in metric, the two sets of data dint interchange in an engineering type formula like this. The bolts tensile strength also will vary slightly with the temperature of the bolt. The pressure the injector exerts on the bolts wont be the PSI generated in the cylinder either. It will be the same PI x the injectors combustion chamber diameter's radius squared, and multiply it times the maximum combustion chamber pressure. It is sort of like a mini engineering project. BotXXXXX XXXXXne is Sprinters did have excessive problems with the injector bolt failure, and leaking injectors, you can document this with an internet search. If you have any more questions, as always, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
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