What Causes Excessive Blow-by in Multi-Cylinder Diesel Engines?
1 Answers
Diesel engine excessive blow-by can be caused by the following reasons: Severe wear of piston rings and cylinder liners in the engine: Piston top erosion or cylinder scuffing: If the piston rings and cylinder liners are severely worn or the piston top is eroded/scuffed, the sealing between the piston rings and cylinder liners becomes compromised. During the compression and expansion strokes of the diesel engine, a significant amount of compressed gas can enter the crankcase through the tiny gaps between the piston rings and cylinder liners. This leads to increased crankcase exhaust pressure. Main symptoms include severe blow-by from the breather, insufficient engine power, and possibly blue smoke emission. Incorrect installation of engine piston rings: Piston ring misalignment: If the piston rings are installed incorrectly with all gaps aligned, even if the rings themselves are not worn, a large amount of high-pressure gas from the compression and expansion strokes will enter the crankcase, causing increased crankcase exhaust pressure. Alternatively, piston ring sticking, breakage, or loss of elasticity will all result in poor cylinder sealing, allowing combustion gases to leak down into the crankcase and significantly increasing crankcase exhaust pressure.
