Chrysler Repair: Torque specs: 3.5L connecting rod cap., torque measurement, correct torque
QuestionQUESTION: Hello, I am in need of the torque specs for the connecting rod bearing caps for a 2002 300m 3.5 h.o. . I have come across a few but they vary from 40 lbs to 55 lbs. I dont know which one would be correct for this motor. Thank you for any info you may have.
ANSWER: Hi Paul,
Both the '98 and the '04 manuals I have show the torque to be 40 foot-pounds + 1/4 turn. The spec in N-m is 54 + 1/4 turn, so that may be why the discrepancy in your recollection.
Please see the PS below about a rating/nomination of my answer/me.
Thanks,
Roland
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QUESTION: Thank you for your knowledge and fast reply. Why is there an added 1/4 turn? Wouldn't this in reality equal to about 45 lbs. and why wouldn't/shouldn't it be listed that way? Sometimes things are just made more complicated than need be. Thank you again, you have been very helpful, Paul.
AnswerHi Paul,
That is an interesting question...and one I don't know the answer too. It is quite common for many other torque specs in the Chrysler engine line. Perhaps it is that 40 is a more precise specification to achieve and that an additional quarter turn adds just the correct additional amount of torque in comparison to say seeking 60 foot pounds in a single 'go' at it. I have to beg ignorance but nonetheless I would do it the way it is stated. Possibly when you reach torque levels above around 40 foot pounds or so a variable amount the frictional issues between the two surfaces which could be related to the presence or absence of trace amounts of grease can result in a false torque measurement. So 40 plus a quarter turn may give the correct torque no matter what the metal surface issues might happen to be. And by the way that extra 1/4 turn should be done with a solid handle not a torque wrench.
Thanks for the rating/nomination...which you may to again if you feel so inclined.
Roland