CAP 9K0725 - Caterpillar

3003 Engine
Markings on the Piston
Illustration 1 g00453417
Marks on the connecting rod and pistonThe pistons and connecting rods are matched to each cylinder. Note the position of each connecting rod and piston for correct assembly.Identification marks (1) on the connecting rod and the connecting rod cap must align. When the connecting rod is installed correctly, the marks should face the right side of the engine.Note: Install the pistons from the front of the engine in ascending order.Note: Be sure that the end gaps of all the piston rings have 120 degrees spacing from each other.Piston Rings
Illustration 2 g00388210
Piston and rings on the 3003 engineThe pistons have a flat crown. The piston crown does not have a chamber.Note: If the piston ring end gap or the ring clearance in the groove is greater than the maximum, replace the piston ring. (1) Top piston ring Shape of top ring ... Barrel faceNote: Install the piston ring with the scribe mark toward the top of the piston. (2) Intermediate ring Shape of intermediate ring ... TaperNote: Install the piston ring with the scribe mark toward the top of the piston. (3) Oil control ringNote: Install the piston ring with the scribe mark toward the top of the piston.The oil control ring on the 3003 engine has three components: oil control ring (3), spring (5) and latch pin.Note: When the latch pin is installed in spring (5), ensure that the gap of the latch pin is 180 degrees away from the gap in the spring before you install oil control ring (3) . (4) Snap ring grooveNote: Use a piston to insert the piston ring square with respect to the cylinder bore. The top surface of the piston ring should be equally distant from the face of the cylinder block at all points before the piston ring end gap is measured.
Illustration 3 g00751702
(6) Thickness gauge (7) Piston ring Gap for No. 1 piston ring ... 0.15 to 0.27 mm (0.0059 to 0.0106 inch) Service limit for No. 1 piston ring ... 1.0 mm (0.0394 inch) Gap for No. 2 piston ring ... 0.12 to 0.24 mm (0.0047 to 0.0094 inch) Service limit for No. 2 piston ring ... 1.0 mm (0.0394 inch) Gap for oil control ring ... 0.20 to 0.35 mm (0.0079 to 0.0138 inch) Service limit for oil control ring ... 1.0 mm (0.0394 inch)Measure the clearance between the piston ring groove and the piston ring. If the clearance exceeds the service limit, then replace the pistons and the rings. Clearance for the No. 1 piston ring ... 0.06 to 0.10 mm (0.0024 to 0.0039 inch) Service limit for No. 1 piston ring ... 0.25 mm (0.0098 inch) Clearance for No. 2 piston ring ... 0.05 to 0.09 mm (0.0020 to 0.0035 inch) Service limit for No. 2 piston ring ... 0.25 mm (0.0098 inch) Clearance for the oil control ring ... 0.02 to 0.06 mm (0.0008 to 0.0024 inch) Service limit for the oil control ring ... 0.15 mm (0.0059 inch)Pistons
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