Is Replacing the Crankshaft Considered an Engine Overhaul?
3 Answers
Replacing the crankshaft is considered an engine overhaul. Below are relevant details about engine overhauls: Introduction: A major engine overhaul for automobiles primarily includes replacing components such as valves, pistons, cylinder liners, or performing cylinder boring and crankshaft grinding. According to the standards of most 4S shops, it generally requires replacing four sets of components: pistons, piston rings, valves, valve oil seals, valve guides, crankshaft bearings, and connecting rod bearings. Maintenance Notes: Remove sludge from the throttle body. The formation of sludge in the throttle body can be attributed to various factors, including carbon deposits from exhaust gases of fuel combustion accumulating in the throttle body, as well as residues from impurities not filtered by the air cleaner. Excessive sludge can cause air intake resistance, leading to increased fuel consumption. Clean carbon deposits from the fuel injectors. Carbon deposits easily form in the combustion chamber, which can result in difficulty starting the engine. Carbon deposits in the fuel injectors can also lead to clogged fuel passages, distorted fuel injection, poor atomization, and naturally increased fuel consumption.
Replacing the engine crankshaft absolutely counts as a major overhaul! I went through this last year—the entire engine had to be completely disassembled. The mechanic said they first had to drain the oil, remove the oil pan, take off all the connecting rods and pistons, and only then could they pull out that metal shaft with the crank. After installing the new crankshaft, they had to use precision tools to adjust its position, ensuring all clearances were exact. What made it even more tedious was the 500-kilometer break-in period afterward, with engine speed kept below 3,000 rpm. The labor and parts costs alone were equivalent to half a year’s fuel expenses, and a car with a disassembled engine takes a hit in resale value—truly painful.
From a repair classification perspective, replacing the crankshaft constitutes an engine overhaul. When the crankshaft in my old Passat wore out, the repair order was labeled as an 'engine overhaul project'. As a core component, crankshaft replacement requires disassembling the main engine structure, involving cylinder block separation, bearing replacement, and piston-rod reassembly. This operation demands extremely high workshop conditions, which ordinary roadside shops dare not undertake. Post-overhaul, special attention must be paid to initial maintenance - I followed the mechanic's advice and used three consecutive batches of full synthetic oil before daring to rev the engine high. Many people overlook that once a major overhaul is recorded in the vehicle maintenance records, subsequent service intervals must be advanced.
