Bosch 5302 Technical Information download pdf (Page 23)

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Workshop Manual_3 - 4 LD_cod. ED0053025560_4° ed_ rev. 03

Disassembly / Reassembly

Piston ring assembly order

3LD 450, 3LD 450/S, 3LD 510, 3LD 510/S, picture 30

A = slot for rst piston ring (chromium plated)

B = slot for piston ring segment (torsional)

C = slot for third piston ring (oil scraper ring)

4LD 640, 4LD 705, 4LD 820, picture 31

A = slot for rst piston ring (chromium plated)

B = slot for second piston ring (torsional)

C = slot for third piston ring(torsional)

D = slot for fourth piston ring(oil scrarper ring)

Note: before inserting the piston in the cylinder, oil the piston

ringwith engine oil and turn them, thus the cuts are

misaligned.

Piston reassembly

Important

Lubricate the following parts with oil before mounting: the piston

pin, the piston, the cylinder and the big-end bearing.

Couple the piston with the connecting rod, thus the combustion

chamber centre B is perpendicularly under end A of the nozzle

housed inside the head.

Lubricate the piston pin and insert it in the piston, lightly

pressing with your thumb.

Make sure that the two stop rings are well housed inside their

seats.

Clearance volume

A = Clearance volume

B = Head gasket

The thickness B head gasket determines the clearance volume

A which shall be 0.75 ÷ 0.90 mm for 3LD 450, 3LD 451/S, 3LD

510, 3LD 510/S and 0.80 ÷ 1.00 mm for 4LD 640, 4LD 705, 4LD

820.

Measure the piston crown position as to the cylinder surface

and chose a gasket having a suitable thickness.

Always consider that the piston at the top dead centre could be

at the same level, either under or over the cylinder.

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Bosch 5302 Technical Information Page 23