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Check of pistons and rods
Clean the piston from the varnish and remove all debris from the lubricating channel piston and connecting rod. Carefully inspect all parts. Cracks of any nature on the pistons, piston rings, finger on the connecting rod and cover are not allowed. If they have a bad-ass, scratches or traces of wear and tear, these parts should be replaced. When viewed from the piston:
| Fig. 62. The measurement of the gap between the piston rings and the annular grooves in a piston head
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- Measure the gap between the piston rings and the annular grooves in the piston crown with a set of probes (Fig. 62). Nominal clearance for the upper and lower compression rings 1 (Fig. 63) is 0.02-0.07 mm, and for the oil scraper ring 2 - 0.02-0.06 mm. Maximum permissible total wear clearance - 0.15 mm. If there is a gap, it is worn out or the ring or the ring groove of the piston;
| Fig. 63. piston Details: 1 - compression piston rings; 2 - oil ring; 3 - the piston; 4 - a cover of a rod; 5 - a bolt of fastening of a rod; 6 - rod inserts; 7 - rod; 8 - cylinder block; 9 - a lock ring; 10 - the piston pin; Arrow A indicates the direction of the front part of the engine
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- At a time, insert all the piston rings, starting at the bottom with respect to the crankcase in the cylinder bore. Turning one of the pistons upside down by selling ring approximately 15 mm down. Thereafter, they will be directly in the cylinder bore;
| Fig. 64. Measurement gap piston ring in the cylinder bore
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- Insert the piston ring into the groove - the castle, probe to determine the gap (Fig. 64). At the compression piston ring end gap should be 0,2-0,40 mm, while oil scraper ring - 0.25-0.50 mm. Maximum permissible backlash when worn all the rings - 1.0 mm; - If the end gap is too small (for example, the new piston rings, which are also to be measured), it is necessary to increase. Rings are very fragile, so such work should be carried out carefully. It is best to clamp the file in a vise and grind off the end of the ring; - Check for wear and scoring piston pins and bushings rods. Even if only one crank arm is damaged, it is necessary to replace the entire assembly is assembled; - Connecting rod bolts on the VR6 engine are screwed directly into the connecting rods (do not use any nuts) and are so-called "supple screws" that must be replaced after each loosening; - Check the connecting rods with the measuring instrument to twisting and bending.
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