What Causes Diesel Engine Oil Spraying?
2 Answers
Here are the specific reasons for diesel engine oil spraying: 1. Damaged exhaust valve: There is usually an elastic exhaust valve on the valve cover. If the exhaust valve is damaged, engine oil will spray out from it. 2. Clogged or damaged check valve: If the check valve connecting the vacuum pressure and exhaust is clogged or damaged, it may cause oil to spray from the exhaust pipe. 3. Engine cylinder failure: For example, if the piston ring of a cylinder breaks, it can lead to excessive backflow during the engine's compression stroke, causing oil to spray from the exhaust pipe. Generally, oil spraying is mainly caused by a damaged exhaust valve, a clogged check valve, or a blocked exhaust pipe.
I've encountered this issue several times, and it's most annoying during long-distance drives in diesel vehicles. Oil spraying is usually caused by problems in the crankcase ventilation system, such as a stuck or aged PCV valve with severe carbon buildup. When cylinder pressure increases, the oil gets forcibly squeezed out, especially noticeable during sudden acceleration. My old diesel SUV had this exact problem—oil stains all over the engine bay and terrifying blue smoke. The diagnosis revealed worn piston rings causing oil blow-by. If not addressed promptly, internal engine friction worsens, leading to rapid engine failure. I ended up losing tens of thousands on major repairs. Remember, regularly cleaning the ventilation system and using high-quality oil can significantly reduce the risk. Diesel vehicles require diligent maintenance.
