Piston group elements
The correct location of the piston relative to the connecting rod on diesel engines
Examination
1. Before checking pistons with connecting rods, remove the piston rings from the pistons and thoroughly clean the pistons.
2. To remove the piston rings from the pistons, open the ring and insert two or three old feeler blades under the ring, evenly along the circumference, and slide the ring off the piston along them. Be careful not to scratch the piston with the ends of the ring. The rings are very brittle and can crack if unclenched too much. The working edges of the rings are very sharp, so handle them carefully so as not to cut yourself.
3. Keep each set of rings with the piston to reinstall them in their original positions.
4. Clean all carbon deposits from the top of the piston.
5. Remove carbon deposits from the piston ring grooves in the piston using the old ring.
6. After removing the deposits, clean the piston with the connecting rod with a suitable solvent and wipe them dry.
7. When assembling the engine, it is advisable to use new piston rings.
8. Carefully inspect each piston for cracks around the skirt and piston pin holes.
9. Check for wear on the piston skirt, bore in the piston head, and burns on the top of the piston.
10. Pitting marks on the piston indicate that coolant has entered the combustion chamber. It is necessary to find the cause of the liquid entering the combustion chamber and eliminate it.
11. On engines with an aluminum cylinder block with wet liners, the pistons cannot be replaced separately; Pistons are supplied complete with rings and sleeves.
12. Check each connecting rod for wear, cracks, and distortion.
13. It is recommended that at each disassembly, replace the studs and nuts securing the lower head of the connecting rod.
14. On all petrol engines, the piston pins are pressed into the upper head of the connecting rod, so the connecting rods must be replaced in a specialized workshop.
15. On diesel engines, the piston pins are fitted with a sliding fit and are fixed in the piston with two circlips. On these engines, the pistons and connecting rods can be separated as follows.
16. Using the blade of a thin screwdriver, remove the retaining ring from the piston and squeeze out the piston pin by hand. When reinstalling the piston pin, use only new circlips.
17. Check the piston pin and connecting rod bearing for wear.
18. Connecting rods usually do not require replacement unless the engine has seized beforehand.
19. Install the piston on the top end of the connecting rod so that the arrow on the bottom of the piston is located on the side of the marking of the bottom end of the connecting rod. Lubricate the piston pin and insert it into the piston and connecting rod top end. Check that the piston turns easily and freely on the piston pin, then fix the piston pin with new circlips. Check that each circlip is correctly positioned in the piston groove (see fig. The correct location of the piston relative to the connecting rod on diesel engines).