What is the issue of water in diesel engine oil?
2 Answers
Water in diesel engine oil may be caused by the following reasons: 1. Engine water plug leakage: Due to corrosion by scale, the water plug rusts through, allowing coolant to enter the oil passage from the water channel, eventually reaching the oil pan and causing water in the oil. 2. Oil cooler damage: If the pipes of the oil cooler are damaged, external water can seep into the oil cooler, leading to water in the oil. 3. Cylinder liner cracks: Once cracks occur, coolant can directly enter the cylinder and then seep into the oil pan through the cylinder wall. 4. Cylinder liner seal ring damage. 5. Cylinder head gasket damage: If the cylinder head gasket is damaged and the water circulation rate is fast, water from the water channel can flow into the oil passage, causing water in the oil. Below are methods to identify water in the oil: 1. Observe the appearance of the oil. The presence of water can be easily judged by the color. Oil without water appears semi-transparent and shiny, while oil containing water appears opaque brown or yellowish. 2. Check if the coolant contains oil. If certain engine components are damaged, engine coolant can enter the lubrication system and mix with the oil. Oil can also be found in the radiator coolant, making it easy to identify. 3. Check for oil emulsification. If water enters the engine oil, it can chemically react with the coolant under high temperatures, forming an emulsion. Checking the dipstick will reveal a white color with foam. 4. When the oil contains a large amount of water, the oil level will rise. At this point, we can simply judge by observing the oil dipstick level.
I've repaired quite a few diesel vehicles, and common causes of coolant mixing with engine oil include damaged or cracked cylinder head gaskets, which allow coolant to seep into the oil. When water contaminates the oil, it emulsifies and turns milky white, significantly reducing lubrication effectiveness. This increases friction during engine operation, potentially leading to cylinder scoring or even bearing seizure. The impact is severe—coolant temperature gauge spikes and noticeable power loss. During diagnosis, first check for white foam under the oil filler cap, then verify radiator pressure levels. If detected too late, a complete engine teardown for gasket replacement becomes necessary at substantial cost. Develop the habit of visually inspecting oil condition during each refueling—don't wait for catastrophic failure. I recommend biannual maintenance checks of cooling system integrity to ensure optimal vehicle health.
