ENGINE 273 MPFI 129 ENGINE Piston Rings • Ring clearance in the groove: Using a thickness gauge , check each piston ring in its groove for side clearance and, if the limit stated below is exceeded, measure the groove width and ring width to determine whether the piston or the ring or both have to be replaced. PISTONRINGCLEARANCE INGROOVE SR. ITEM STD VALUE LIMIT 1. Top ring 0.03 to 0.07 mm 0.12 mm 2. 2nd ring 0.02 to 0.06 mm 0.1 mm PISTON RING THICKNESS TYPEOFRING RINGSTHICKNESS(MM) 1st Compression Ring 1.2 -0.01-0.03 2nd Compression Ring 1.2 -0.01-0.03 3rd Oil Control Ring 2.0 -0.03-0.13 • Piston ring end gap ( butt clearance ): To measure the end gap, insert the piston ring into the cylinder bore, locating it at the lowest part of the bore and holding it true and square; then use a thickness gauge to measure the gap. If the gap measured exceeds the limit, replace the ring. PISTON RING END GAP SR. ITEM STD VALUE LIMIT 1. Top ring 0.15 to 0.3mm 0.7 mm 2. 2nd ring 0.3 to 0.5 mm 0.7 mm 3. Oil ring 0.2 to 0.7 mm 1.8 mm • Butt clearance of piston ring should be measured in unworn portion of cylinder bore. • In case of any piston ring with any defect, complete ring set should be replaced. • When cylinder bores are re-bored or honed, pistons and rings of appropriate size should be used. • Stagger piston rings gaps such that they are 120° apart. (With butt gap not in line with piston pin).
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