What Causes Engine Cylinder Blow-by?
2 Answers
Engine cylinder blow-by can be caused by the following reasons: 1. Prolonged operation of the engine at excessively high temperatures, leading to inadequate heat dissipation and deformation of the cylinder block due to overheating; 2. Uneven tightening force of the screws between the cylinder gasket and the cylinder block during engine assembly, resulting in excessive air pressure; 3. Poor quality of the engine cylinder gasket, insufficient surface flatness, or the presence of bubbles and uneven edges at the corners; 4. Improper driving habits, such as long-term aggressive driving, causing sudden excessive or insufficient air pressure in the cylinder; 5. Neglecting regular maintenance, such as failing to check whether the radiator has enough water or whether the engine oil is changed properly; 6. Lack of lubrication oil, leading to a sharp rise in friction temperature between the cylinder liner and the piston, as well as between the connecting rods.
A few days ago, my friend's old car fell victim to this—towed to the repair shop only to find out the cylinder head gasket had deteriorated. This part is like the cheese slice in a sandwich; if the seal fails under high temperature and pressure, coolant can leak into the cylinders. Insufficient coolant or a blocked cooling system can also cause the engine to overheat and warp, leading to loose sealing surfaces and fluid leakage. Another scenario is when the cylinder head bolts are loose or not tightened to the specified torque, causing the seal to fail under prolonged vibration. The worst is using low-quality antifreeze, which can boil at high temperatures, creating bubbles and causing localized overheating. Never ignore this issue—if you see the temperature gauge in the red, white smoke from the exhaust with a sweet smell, shut off the engine immediately and call a tow truck, or the engine could be completely ruined.
