A wet sump oil system is the most common lubrication setup found in production vehicles, designed to keep engine components properly oiled and cool. It works by storing engine oil in a reservoir located at the bottom of the engine itself, known as the oil pan.
The core function of this system is to continuously circulate oil from this pan through the engine and back again.
How the Wet Sump System Operates
Here's a breakdown of the typical flow and components in a pressurized wet sump system:
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Oil Storage: The engine oil is stored in the oil pan, located directly beneath the crankshaft and other moving parts. The oil pan acts as both the reservoir and the base for the system.
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Oil Pickup: An oil pump, often situated within the oil pan itself, uses a pickup tube that extends into the oil bath.
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Pumping: The oil pump sucks oil from the pan.
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Filtration: The pump then pumps the oil through the oil filter. This filter removes contaminants like metal shavings, dirt, and sludge, ensuring only clean oil circulates through the engine.
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Distribution: From the filter, the pressurized oil is sent through the oil passages of the engine – a network of internal channels and galleries.
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Lubrication & Cooling: The oil is routed to the various locations requiring oil, such as:
- Crankshaft and connecting rod bearings
- Camshaft bearings and lobes
- Pistons and cylinder walls
- Valvetrain components
- Turbocharger bearings (if equipped)
At these points, the oil forms a protective film, reducing friction and wear. It also absorbs heat generated by the moving parts, helping to regulate engine temperature.
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Return: After lubricating the components, the oil flows back down into the oil pan, primarily driven by gravity, completing the cycle.
Key Components
- Oil Pan: Stores the oil, serves as the "wet sump."
- Oil Pump: Sucks oil from the pan and pressurizes it for circulation.
- Oil Filter: Cleans the oil before it circulates.
- Oil Passages: Internal channels within the engine block and cylinder head that direct the oil flow.
- Oil Pickup Tube: Connects the oil pump intake to the oil in the pan.
Advantages and Considerations
- Simplicity: Wet sump systems are simpler and less expensive to manufacture compared to dry sump systems.
- Compactness: Components are generally integrated closely with the engine.
- Common Use: This system is standard on most production vehicles due to its effectiveness for typical driving conditions.
While effective for most applications, hard cornering or acceleration can sometimes cause the oil to slosh away from the pickup tube in the pan, potentially leading to temporary oil starvation in high-performance scenarios. However, for daily driving, the wet sump is a reliable and efficient lubrication method.
