Check of pistons and rods

Carefully check all the details. If they have a bad-ass, scratches or traces of wear and tear, these parts should be replaced.

Measure the clearance height between the piston rings and the grooves using a probe (Fig. 427). If the compression ring gap greater than 0.25 mm, clearance scraper ring or more than 0.15 mm, the worn or rings or piston. Nominal values are shown in the table of tolerances and control.

In turn, 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 20 mm down. Thereafter, they will be directly in the cylinder bore.

Insert the gap between the two ends of the ring probe to measure the end gap of the piston ring. In Fig. 428 shows how to correctly measure the brightness of the gap. In compression piston ring gap should be equal to 0.2-0.4 mm; from oil rings - 0.25 to 0.4 mm. The boundary of the wear ring is 1.0 mm.

With slight gap (for example, new rings, which should also measure) ends of the rings can whittle file. To do this, hold down the file in a vise and grind off the ends of his rings. Too much heat gap corresponding ring should be replaced.

Check for wear and scoring piston pins and bushings rods. Also if only one crank arm is damaged, it is necessary to replace the whole piece assembly. The bolts connecting rod bearings are always replaced by new ones. Check the connecting rods with a device for straightening rods on deformation and twisting. The values obtained should be minimal. If you have any doubts about the condition of the connecting rods, then contact the service station to spend the appropriate measurements. If a bent rod, it is necessary to change the whole set.