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Connecting rods and pistons - check status
1. Carefully clean the pistons of a deposit and carefully remove the ring. 2. Remove the carbon deposits from the piston ring grooves (photo). 3. Rinse the pistons and rods solvent, carefully clean the drain holes in the grooves of the piston and the connecting rod hole (photo). 4. If there are no signs of significant wear and if the cylinder bore is not required, the pistons should not be changed. Normal wear manifests itself in the form of the uniform vertical development in the friction of the piston and a slight easing of landing the top compression ring. However, replacement of piston rings in the engine overhaul is required.
| 15.2a Clean the groove of the pistons using tool ... |
| 14.4b Marks of dimensional group of pistons on V6 unit |
5. Carefully inspect for cracks on the piston skirt for the piston pin bosses and landings of piston rings. 6. If the piston there are chips and burrs, it indicates frequent engine overheating. In this case a careful check of the lubrication and cooling systems. Burn-out in the bottom of the piston indicates the engine with an incorrect ignition timing setting. The cause erosion at the edges of the piston head is usually abnormal combustion (detonation). If these defects are found, it is necessary to find and eliminate the cause. 7. Corrosion of the piston in the form of small pits (pitting) indicating that the penetration into the combustion chamber (and in the crankcase, crankshaft) of the coolant. 8. Measure the gap between the groove and the new ring (photo). If the backlash exceeds the limit, the piston must be replaced. 9. Check the clearance between the piston and the cylinder, measure the diameter of the cylinder (see. Above) and the diameter of the piston of the cylinder (see photo). If the clearance exceeds the limit, then the cylinder block to be boring, but the pistons and rings should be replaced by repair. 10. Check the clearance between the piston pin and connecting rod, which rocking piston and connecting rod in opposite directions. If you play a tangible, the hole for the thumb should be to deploy and install a new finger.
| 15.2b ... or an old piston ring |
| 15.3 The opening for discharging oil in the rod |
11. Repair of pistons and rods is performed in the service station. 12. Check on rods cracks and other damage. Remove the connecting rod bearing caps, remove the bearings, clean the seating surfaces on the cover and on the connecting rod, check for cracks, scratches and scuffing. After checking the reassemble rod, setting in place the bearings, tighten the nuts by hand.
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