Answer MEP Question 28

Q. Express your reactions and state the subsequent investigation you would make If a laboratory report on a used diesel engine oil sample indicated the presence of appreciable amounts of: -A. Iron; B. Copper; C. Antimony and De Tin; E. Silicon. 

A. Iron Excess of iron in the lube oil sample is the result of the following engine components wearing out, - The following engine components shall be clearly inspected and close attention to be paid for subsequent c/case inspection. - Cylinder walls and liners a Crank and cam shafts; - Valve guides; -- Rockers; ▪ Rings; - Bearings; • Gears; Shafts 

B. Copper • Copper in c/case lube oil is mainly due to bearing metal failure and wear on one of them. Copper is usually alloyed in the form of brass, bronze or as sintered copper—lead. - The following engine components shall be closely inspected. Big-end and crankshaft bearings; Bushings; Oil coolers and cooler core tubes; e thrust washers; e Fuel transfer pumps; - Governor and wrist pin bushings. - Copper-type anti-seize compounds 

C. Antimony ▪ Excessive Antimony indicates wear of white metal. -'white metal" These alloys usually consist of relatively hard crystals embedded in a softer matrix, a structure important for machine bearings. They are composed primarily of tin, copper, and antimony, with traces of other metals added in some cases and lead substituted for tin in others. • Main Bearing shell - Bottom end bearing shells - cross head bearing etc., 

D. Tin Excess of Tin(Sn) is the most probable cause of Excessive wear of the following components; 

- Bearings; . Bushings; . Thrust washers Any white metal part in crankcase 

E. Silica Nothing but Dirt. Highly abrasive. Main source is "Air intake". - Sources include inadequately filtered air due to cracked induction piping or hoses, - Defective or incorrectly fitted air filters and gaskets. - Dirty oil filling or sampling equipment. Incorrectly fitted or missing oil filler caps. • Ineffective reservoir breathers.