Note. Avoid touching the new bearing surfaces with bare hands to avoid unwanted contact of the bearings with traces of oil and chemicals that are always present on the fingers.
1. Before installing the connecting rod and piston assemblies, the cylinder walls must be thoroughly wiped, traces of stepped wear are completely removed from their upper edges and a chamfer is removed. It is understood that the crankshaft is already installed in its regular place in the block.
2. Remove the cover of the lower head of the connecting rod of the piston of the first cylinder (check the factory or dismantled marks). Remove the old bearing shells from the connecting rod head and its cover and carefully wipe their beds with a clean, lint-free rag.
3. Wipe the back of the new upper shell and place it in the bearing bed in the connecting rod head. Make sure that the guide tab of the bushing falls into the reciprocal groove in the connecting rod. In no case do not tap the liner into the bed with a hammer. Do not lubricate the bearing with anything at this stage.
4. Wipe the back of the second bearing and place it in the connecting rod cap. Again, make sure that the tongue falls into the reciprocal groove. Do not use any lubricant - it is extremely important that the mating surfaces of the bearing and connecting rod remain absolutely clean and dry.
5. Arrange piston rings locks as it is shown in an accompanying illustration.
Attention! NEVER position the ring locks coaxially with the piston pin or perpendicular to its axis.
6. Pull the pieces of the old fuel hose onto the connecting rod cap bolts to protect the cylinder mirror and the crankshaft journal from accidental damage during the installation of the connecting rod and piston assembly.
7. Lubricate the piston and piston rings with clean engine oil and fit the mandrel of the ring crimping tool onto the piston. Leave the piston skirt protruding from the tool mandrel by about 6.4 mm for free threading into the cylinder. The rings must be pressed flush with the forming surface of the piston.
8. Rotate the crankshaft so that the neck of the first crank is in the BDC position. Lubricate the mirror of the first cylinder with impellent oil.
9. Expanding the assembly with a mark in the form of a recess or an arrow on the piston bottom forward along the engine (see accompanying illustration), carefully tuck the connecting rod into the first cylinder of the block. Insert the piston skirt into the cylinder, firmly pressing the lower edge of the mandrel of the ring crimping tool against the surface of the block.
10. Tap the top edge of the mandrel to ensure it is firmly pressed against the block around the entire perimeter of the bottom edge.
11. Gently tapping on the bottom of the piston with a wooden hammer handle (see accompanying illustration), insert the piston into the cylinder while guiding the bottom end of the connecting rod against the crank pin of the crankshaft. Piston rings can suddenly pop out from under the tool mandrel, so constantly monitor its tightness against the block. Act slowly, if the slightest resistance occurs, immediately stop the piston knocking. Find out the cause of jamming and eliminate it. Never try to push the piston into the cylinder by force - this can lead to mechanical damage or destruction of the piston rings.
Checking the operating clearance of the connecting rod bearing
1. After the introduction of the connecting rod and piston assembly into the engine, before the final installation of the cover of the lower head of the connecting rod, you should check the working clearance of the connecting rod bearing of the crankshaft.
2. Cut a piece of calibrated plastic wire from the Plastigage measuring set, a length slightly shorter than the width of the connecting rod bearing shell, and lay it along the first crankshaft journal, parallel to the axis of the latter (see accompanying illustration).
3. Wipe the bearing surface in the connecting rod cap, remove the protective hoses from the mounting bolts and install the cover on the connecting rod. Make sure that the mark on the cover is turned in the same direction as the mark on the connecting rod.
4. Having previously lubricated with oil, screw on the cover fastening nuts and tighten them with the required force. Use a thin-walled socket to avoid jamming the key. If there are signs of a wrench jamming between the nut and the connecting rod, slightly raise the head and continue tightening. Do not rotate the crankshaft while tightening the connecting rod bearing cap fasteners.
Note. Do not allow the crankshaft to rotate during the entire procedure.
5. Turn away nuts and carefully remove a cover from a rod. Take care not to damage the flattened piece of gauge wire.
6. According to the width of the flattened wire, measured on the scale printed on the packaging for the Plastigage set (see accompanying illustration), determine the operating clearance in the bearing. Compare the measurement result with the requirements Specifications.
7. If the gap is out of range, before looking for liners of a different size, check if dirt / oil has got under the backs of the liners nested in the connecting rod and the cover of the liners. Re-measure the diameter of the shaft journal. The flattening of the wire from one end more than from the other indicates the presence of a neck taper.
Final installation of the connecting rod and piston group
1. Using your fingernail or the edge of an old credit card, carefully scrape off any traces of gauge wire from the journal and/or bearing surface.
2. Make sure both bearing surfaces are absolutely clean, then lubricate them evenly with a thin layer of molybdenum-containing motor assembly grease. To gain access to the surface of the upper bearing, you will have to push the piston into the cylinder a little - do not forget to put protective hoses on the connecting rod cap bolts to avoid damaging the surface of the shaft journal. Try to prevent the piston rings from popping out of the cylinder.
3. Return the connecting rod to its place, carefully putting it with the lower head on the neck of your crank, remove the protective hoses from the bolts, install the cover and tighten the fixing nuts in two steps to the required torque.
4. Repeat the entire procedure for the remaining connecting rod and piston assemblies.
5. Keep in mind the following important points:
- a) Make sure that dirt does not get on the backs of the liners and their beds in the connecting rods and covers;
- b) Make sure that each assembly is installed exactly in its cylinder (even in the case of new components, as the piston ring gaps have been adapted to specific cylinders);
- c) The pistons must be located with a mark / arrow on their bottom forward of the engine (towards the timing drive);
- d) Do not forget to lubricate the cylinder mirrors with engine oil before installing the assemblies;
- e) Before the final installation of the bearing caps, after checking the operating clearances in the latter, do not forget to lubricate the bearings.
6. Having finished installing the connecting rod and piston assemblies, check the freedom of rotation of the crankshaft by turning it several times by hand.
7. In conclusion, it is necessary to check the axial play of the crankshaft again (see Removal of connecting rod and piston assemblies).
8. Compare the results of the end play measurements with the requirements Specifications. If the backlash was normal before disassembling the engine and old connecting rod and piston assemblies were used, there should be no surprises. If the backlash goes beyond the permissible limits after replacing the connecting rods, the latter must be removed from the engine and sent to a car service workshop for appropriate machining.