Is an Overhauled Car Engine the Same as a New Engine?
2 Answers
An overhauled engine is completely different from a new engine, and its performance is generally worse after overhaul. Here are the detailed reasons why an engine's performance changes after an overhaul: General Reason : Cars are mass-produced industrial products. The reassembly after an overhaul can hardly achieve the standardized level of the production line. Therefore, in most cases, the engine's performance will be worse after an overhaul. Bolt Reason: Normally, the bolts on an engine are tightened in a specific state and sequence. During the reassembly after an overhaul, the handling of bolts is often not as precise.
Having repaired cars for decades, I firmly believe that an overhauled engine can never perform like a brand-new one. A new engine fresh off the production line has all components installed from scratch, undergoes rigorous testing, and delivers stable and reliable performance. During an overhaul, although worn parts like piston rings, bearings, and gaskets are replaced, core components such as the crankshaft or cylinder block remain used and may have hidden cracks or deformations. The assembly precision is also inferior, leading to rough operation, increased noise, and higher fuel consumption—whereas a new engine delivers full horsepower and runs smoothly. Moreover, an overhauled engine has a shortened lifespan, typically lasting only 50,000 to 60,000 kilometers before issues arise, while a new one can easily surpass 100,000 kilometers. If the budget allows, I recommend opting for a replacement to avoid repeated repairs. Regular maintenance can extend the service life of an overhauled engine.
