Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay.
Your engine is the 648.961.
Your compression needs to be between 29 and 35 bar ( 420 to 508 psi)
Your wear tolerance can be between 18 bar less then 29 ( 260 psi )
The difference tolerance between each cylinder for compression is 3 bar ( 43 psi)
If the compression is all in range here the engine compression is o.k,
The black smoke can be caused by an injector leaking down or allowing to much fuel into a cylinder.I have also seen a restricted engine air filter cause this issue needing replaced or on some models equipped with a mass air flow sensor this sensor can be faulty needing replaced as well.
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