Mercedes Repair Questions? Ask a Mechanic for Answers ASAP
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With a blue smoke this can indicate engine oil being burned and this can be due to piston ring failure or cylinder wall damage in some cases.This will have to be checked into further to locate the source of the smoking issue here then repaired and see if the engine continues to run rough after this has been done.The smoking is an indication of the engine burning a fluid and it sounds like engine oil which in turn can cause the engine to run rough.
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If it is an oil ring failure on a piston in allot of cases compression may be o.k. but the oil can leak past the ring and cause the smoke issue and running issue here.The cylinder may have a cooler temp then the rest I would think if a piston ring is allowing oil into the cylinder.
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