Device Features
The pistons are made of aluminum alloy and have a cylindrical recess in the bottom.
Piston pins steel, polished, floating. From axial displacement, they are held by two retaining rings. Three rings are installed on each piston: two compression and one oil scraper. Rings are installed on the piston with a mark «Thor» («Top») to the bottom of the piston.
Connecting rods are steel, forged, with an I-section rod, with thin-walled liners. A bushing is pressed into the upper head of the connecting rod. The maximum allowable clearance in operation between the liners and the connecting rod journals of the crankshaft is 0.12 mm.
The maximum axial clearance of the connecting rod on the crankshaft journal is 0.37 mm.
Checking the technical condition
Remove piston rings and clean pistons from carbon deposits. Determine the degree of wear of the pistons by measuring the diameter of 10 mm from the edge of the piston skirt perpendicular to the axis of the piston pin (pic. 2-9). the piston must be replaced if its diameter differs by more than 0.04 mm from the permissible values (tab. 2-2).
Replace piston rings or pistons if gaps between piston ends and grooves (pic. 2-10) exceed the allowable values (tab. 2-3).
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