Piston ring gap
1. Install the piston ring in the cylinder as shown in the figure, and measure the gap in the lock using a set of flat feeler gauges (1).
Compare the results with the original values:
- lock in compression ring: 0.25-0.40 mm;
- gap in the oil scraper disc: 0.25-0.75 mm.
2. If the clearance in the lock is greater than the allowable value, the piston ring must be replaced.
3. Measure the piston ring backlash as shown.
Compare the results with the original values:
- side clearance of the compression ring: 0.25-0.7 mm;
- side clearance of the oil scraper ring: 0.04-0.12 mm.
4. If the gap exceeds the allowable value, replace the piston ring with a new one. If the clearance is still too large, replace the piston.
Clearance in connecting rod bearings
1. Install the bearings in the connecting rod and the connecting rod cap.
2. Tighten the connecting rod cap bolts:
- Tighten connecting rod cap bolts to 10 Nm.
- Tighten the connecting rod cap bolts an additional 60°using tool EN-470-B.
- Tighten the connecting rod cap bolts an additional 15°using tool EN-470-B.
3. Using a bore gauge, measure the inner diameter of the hole of the lower head of the connecting rod with the liners installed at three points, as shown in the figure (1).
4. Calculate the average value of the inner diameter of the hole of the lower head of the connecting rod with liners installed:
(Result 1 + Result 2 + Result 3): 3
5. Using a micrometer, measure the diameter of the connecting rod journal of the crankshaft in two planes between points 1-3 and 2-4.
6. Calculate the average diameter of the connecting rod journal:
(Result 1 + Result 2): 2.
7. Subtract the average diameter of the connecting rod journal from the average diameter of the hole in the lower head of the connecting rod with liners installed to obtain the clearance between the connecting rod journal and the connecting rod. The gap should be 0.013-0.061 mm.
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