How to Determine if the Engine is Seized?
3 Answers
Methods to determine if the engine is seized include insufficient coolant level and high water temperature. Engine maintenance involves the following three points: 1. Clean the air filter: The air filter is related to the engine's air intake during driving. If the air filter is clogged or accumulates too much dust, it will hinder the engine's air intake. Additionally, a large amount of dust entering the cylinder will accelerate carbon buildup, causing poor engine ignition, insufficient power, and naturally increased fuel consumption. 2. Remove throttle sludge: Throttle sludge is formed due to carbon deposits from fuel combustion exhaust at the throttle and residues of impurities not filtered by the air filter. Excessive sludge can cause air resistance, leading to increased fuel consumption. 3. Clean injector carbon deposits: The combustion chamber is prone to carbon buildup, which can cause difficulty in starting. Injector carbon deposits can also block fuel passages, deform gasoline injection, and result in poor atomization, naturally increasing fuel consumption.
Last time I encountered a seized engine while repairing a car, and the crankshaft wouldn't budge—it was a real hassle. First, try the most basic trick: use a socket wrench on the crankshaft bolt to turn it. If it doesn't move, there's likely an issue. If you have the tools, remove the spark plugs and use a cylinder pressure gauge to test. If the needle doesn't move, it's almost certainly seized. If all else fails, pulling the cylinder head to inspect the cylinder wall scratches and piston condition is the most accurate method. A seized bearing will give off a burnt smell, and bearing fragments can clog the oil pan filter. Be extra careful with overhauled cars—poor oil cooling or oil pump failure can cause a recurrence. I remember during the last disassembly seeing the crankshaft and bearings fused together, and replacing the whole set cost several thousand. Regular oil changes are absolutely crucial.
The most direct method to check is by rotating the crankshaft. Use a 24mm socket to turn it counterclockwise; a normal engine should rotate more than 20 degrees. If it's completely stuck, check for water ingress and rust, especially in flood-damaged vehicles, which often have this issue. For turbocharged engines, also inspect the turbo bearing for seizure—I've encountered cases where deformed turbo blades locked up, preventing the crankshaft from turning. In the event of bearing failure, you'll find the oil pan magnet covered in metal shavings, with bearings crushed into foil-like fragments. Bent connecting rods can also jam the piston; use a plastic hammer for gentle tapping during disassembly. The worst-case scenario is a deformed crankshaft itself—if a dial indicator shows over 0.3mm runout, replacement is mandatory.
