Is Replacing the Cylinder Head Assembly Considered a Major Overhaul?
3 Answers
Replacing the cylinder head assembly is considered a major overhaul. Typically, the causes of cylinder head damage in automobiles include: alloy cylinder heads exposed to high temperatures; uneven tightening torque of cylinder head bolts; extensive burning of the cylinder gasket; and other external forces causing cylinder head damage. The problems caused by a damaged cylinder head are as follows: 1. While driving, you may often feel the engine lacks power and has difficulty accelerating. There may be air leakage sounds at the joint between the cylinder head and the cylinder block or in localized areas; 2. After starting the engine, one or two cylinders may not function, producing a 'bang, bang' sound. The radiator may continuously lose water, with bubbles appearing at the radiator filler neck, or oil droplets may be visible on the surface of the coolant; 3. When checking the engine oil by pulling out the dipstick, the oil may appear milky white. Water droplets may continuously flow out of the exhaust pipe; 4. The engine may overheat. When the cylinder gasket is severely damaged, not only does the engine power drop significantly, but sometimes it may even fail to start. Generally, when such faults occur, replacing the cylinder head is sufficient, and the engine oil should also be changed simultaneously.
I've driven several cars and often tinker with repairs myself. As for whether replacing the cylinder head assembly counts as a major overhaul, it's an interesting question. Strictly speaking, a major overhaul refers to completely disassembling and refurbishing the engine, such as replacing core components like piston rings and crankshafts—it's a thorough restoration process. Replacing the cylinder head assembly, on the other hand, only involves working on the top part of the engine. It's a common repair procedure, often needed when valves fail or the head gasket wears out. The job is labor-intensive and may come with high labor costs, but it doesn’t affect the engine’s overall lifespan like a major overhaul would—unless other parts are also disturbed. In fact, the car might even become more fuel-efficient after the repair. My advice is to first get a proper inspection from a trustworthy shop if you encounter such issues, so you don’t get talked into unnecessary work. In short, it’s not strictly a major overhaul, but it’s definitely a big job.
I usually pay attention to saving money when driving, and I don't consider replacing the cylinder head assembly as a strict overhaul. An overhaul typically involves completely disassembling the engine, which can be shockingly expensive, while replacing the cylinder head is just a partial repair, usually costing within a few thousand yuan—much cheaper compared to an overhaul bill that can run into tens of thousands. However, this job is quite troublesome—you have to remove the engine’s top cover, and after replacement, you need to adjust the valve clearance, otherwise, there will be noise while driving. I’ve been through it once myself; after the repair, you need to be careful during the break-in period and avoid rushing into high-speed driving. This can also help maintain the car’s performance, which isn’t a bad thing. If you’re on a tight budget, finding a skilled technician is crucial. Don’t hesitate to ask for details to avoid future issues.
