What Needs to Be Replaced During a Major Car Overhaul?
3 Answers
Here are the specific details of a major car overhaul: Major engine overhaul: Mainly includes replacing valves, pistons, cylinder liners, or cylinder boring, crankshaft grinding, etc. Items to be replaced: According to general 4S shop standards, the following 4 sets of components need replacement: pistons, piston rings, valves, valve stem seals, valve guides, crankshaft bearings, connecting rod bearings, timing belt, and tensioner pulley. Additionally, machining work is required, such as cylinder boring and sleeving, crankshaft grinding, cold pressing of valve guides. Replacement parts also include overhaul gasket kits, front crankshaft oil seal, rear crankshaft oil seal, camshaft oil seal, oil pump, valve lapping, etc. Ensuring engine performance: Sometimes external components like clutch discs also need replacement. Essentially, any parts with uncertain reliability should be replaced to restore the engine's operational performance.
When it comes to a major car overhaul, my experience is that the engine overhaul is the most critical. It's essential to replace worn-out components like piston rings and pistons, as these parts in older cars tend to seize up over time, affecting compression performance. Next are the valves and cylinder liners—if they're not replaced with new ones, air leakage can cause the engine to shake and lose power. Various seals, such as the rear crankshaft oil seal, must also be replaced to prevent oil leaks and related issues. Don’t overlook the main bearings and connecting rod bearings—if inspection reveals wear, replace them to avoid excessive noise and engine damage during operation. Additionally, supporting components like the water pump and thermostat should be renewed, as they handle cooling and can lead to dangerous overheating if faulty. I recommend changing the engine oil and oil filter during every major overhaul to give the engine a fresh start. After an overhaul, fuel consumption typically drops, and performance becomes more stable. Regular maintenance can also help prevent the need for frequent overhauls.
As an average car owner, a major overhaul mainly involves replacing the engine's internal consumable parts. Piston rings are crucial as they handle compressed gases—once worn out, they cause oil consumption. Valves and cylinder liners also need replacement to maintain combustion efficiency. Sealing components like valve cover gaskets should be renewed to prevent oil leaks. For bearings, inspect the connecting rod and main bearings, replacing them if necessary to avoid noise. Additionally, replace the timing belt or chain to prevent breakage-related failures, and the water pump often requires replacement too. The repair costs are indeed significant, but in the long run, it saves money by reducing the frequency of minor repairs. The engine runs smoother and safer during driving, and I've also learned that routine maintenance, such as timely oil changes, can delay the need for a major overhaul.
