Connecting rod and piston group — check (Nissan Sunny B13)

Correct relative orientation of the piston and connecting rod

1. Before checking, the connecting rods and pistons should be cleaned and the old rings should be removed from the piston.



2. Carefully spread the ring, moving it to the top of the piston. To prevent the ring from falling into an empty groove when removing it, place two or three old feeler gauges under the ring.

3. Scrape off any carbon deposits from the piston crowns. After removing the top rough layer of carbon, clean the piston crowns by hand with a wire brush (or with sandpaper on a cloth backing).



4. Carefully remove carbon deposits from the piston grooves using an old broken piston ring.

5. Wash the piston assembly with the connecting rod in a solvent, dry thoroughly. Make sure that the oil drain grooves in the piston ring grooves are clean.

6. Measure the piston diameter perpendicular to the piston pin axis with a micrometer (at a given distance from the edge of the piston skirt) and compare the result with the standard. The piston size group is stamped on its bottom. If the piston wear exceeds the maximum permissible value, the piston must be replaced.

7. Check the clearance between the piston ring and the wall of the piston groove. To do this, insert the ring from the outside into the corresponding groove and measure the clearance between the upper surface of the ring and the wall of the groove with a feeler gauge. If the clearance exceeds the norm even with a new ring, replace the piston.

8. Check the gap in the piston ring joint by inserting the ring into the corresponding cylinder and pushing it with the piston bottom to prevent the ring from being skewed during measurement. Push the ring to such a depth that the edge of the piston skirt is aligned with the split plane of the cylinder block, then remove the piston. Measure the gap with a feeler gauge. If the gap exceeds the norm, replace the rings and repeat the procedure. If the gap exceeds the norm with new rings, the cylinder should be bored and honed (see subsection 3.1.2.10).

9. Carefully check for cracks on the piston skirt, on the piston pin bosses and in the areas between the piston ring grooves.



10. Check for chips and scoring on the rubbing area of the piston skirt, traces of burning along the edges of the bottom. If there are chips and scoring, this indicates frequent overheating of the engine, one of the causes of which may be abnormal combustion of the fuel mixture. In this case, a thorough check of the fuel, lubrication and cooling systems is required. Traces of melting on the side surface of the piston indicate a breakthrough of gases from the combustion chamber. Burning of the piston bottom or burnt areas along the edges of the bottom indicate abnormal engine operation due to incorrect ignition timing (too early ignition), or as a result of detonation. If the above defects are detected, their cause must be found and eliminated, otherwise the causes of such wear may continue to manifest themselves in the future. The causes of abnormal engine operation may be air leakage on the intake manifold, incorrect ignition timing, or fuel injection system failure.

11. Piston corrosion in the form of small pits (pitting) indicates penetration into the combustion chamber (and also in the crankshaft housing) coolant. Here again, it is necessary to find the cause and eliminate it.

12. Carefully check the connecting rods for damage such as cracks in the heads near the piston pins and in the places where the connecting rod bearings are installed. Check for deformation of the connecting rod body (twisting or bending). Damage to connecting rods is unlikely and only occurs in cases of engine seizure or severe overheating. A thorough inspection of connecting rods can only be performed in a workshop with the necessary equipment.



13. If necessary, the piston can be removed from the connecting rod and assembled with the connecting rod as follows.



14. Remove the piston pin retaining rings and push the piston pin out. If necessary, support the piston and carefully knock out the pin by hammering the mandrel.



15. Removing the piston pin is made much easier if the piston is heated to 60–70°C.

16. Check the piston pin and connecting rod bore for signs of wear or damage. Check the pin clearance in the piston and connecting rod.

17. If the connecting rod head bushing and piston pin are severely worn, or if the pin clearance in the connecting rod head exceeds the norm, the pin and bushing should be replaced. The connecting rod head bushings should be replaced in a workshop.



18. If the clearance between the piston and the pin significantly exceeds the norm, then the piston and pin should be replaced as a set. Keep in mind that the clearance between the piston and the pin does not play such a significant role as the clearance in the connecting rod head.

19. The connecting rods themselves do not require replacement, except in cases of engine seizure or other serious breakdowns. Check the condition of the connecting rods by inspection; if deformation of the connecting rods is detected, take them to a car service workshop for inspection and repair.

20. Purchase new parts to replace worn out ones.

21. Orient the piston and connecting rod so that the mark on the part of the piston that should be facing the front of the engine (in the form of an arrow or a line) correctly positioned relative to the lubrication hole in the connecting rod body (see Fig. Correct relative orientation of the piston and connecting rod). When properly oriented relative to each other, the mark on the piston should face the front of the engine, and the oil hole in the connecting rod body should face the rear of the cylinder block.



22. Lightly lubricate the piston pin with fresh engine oil and insert it into the holes in the piston and in the connecting rod head. If necessary, tap the pin into place with light hammer blows on the mandrel.

Attention! In order to facilitate installation of the piston pin, it is recommended to heat the piston.

23. Check the freedom of rotation of the pin in the piston bosses, then install the retaining rings in the piston grooves.