Table of Contents
Definition
Crankcase is the body that holds all of the inner components of the engine together. It is the most important part of the engine, however, it wishes to be robust and light.
Description
The crankcase is formed by a section of the cylinder block below the cylinder bore and an engraved or cast metal oil pan that forms the lower skirt of the engine and also acts as a reservoir or sump of lubricating oil.
Two-stroke engines typically use a crankcase compression design. This allows the fuel-air mixture to flow through the crankcase before entering the cylinder. This engine design does not include an oil pan in the crankcase.
4-stroke engines usually have an oil pan at the bottom of the crankcase, and most of the engine oil is held in the crankcase. The air-fuel mixture does not flow through the crankcase of a 4-stroke engine. However, a small amount of exhaust gas often flows in as a “blow-by” from the combustion chamber.
The crankcase often forms the lower half of the main journal, but on some engines, the crankcase completely surrounds the main journal.
Role Of Crankcase
The main purpose of the crankcase is to shield the crankshaft of the engine. It is a part of the engine block installed under the cylinder.
The crankcase is a central component of the engine. Contains the entire crank mechanism, including pistons, cylinders, and connecting rods. Accessories, gearbox, and engine control with cylinder head are mounted on the crankcase.
The universal main function of the crankcase is to protect the crankshaft and connecting rod from dirt. In a simple two-stroke engine, the crankcase has several functions and is used as a pressure chamber for the air-fuel mixture.
In the more complex 4-stroke design, the pistons seal the fuel-air mixture and instead serve primarily to store and circulate the oil. It also acts as a safety feature to keep people away from moving parts, but it’s not straightforward.
Parts Of Crankcase
Crankcase can be divided into 3 major components.
- Upper Crankcase
- Lower Crankcase
- Valve
Let us know about these components briefly:
1. Upper Crankcase
This is the top of the crankcase. Equipped with a camshaft and valve mechanism. There are holes for the intake and exhaust manifolds where the valves and valve leads are located. The camshaft is connected to the crankshaft via the engine belt or chain drive.
2. Lower Crankcase
It is one of the key components of the engine. It is bolted directly to the engine block. The lower crankcase supports the crankshaft of the engine mounted on the case, and the case is submerged in oil to cool and lubricate the shaft.
The crankshaft is mounted using thrust bearings that keep the crankshaft in place. One end of the crankshaft carries a dead load that spills oil on the crankshaft as it spins inside the crankcase.
3. Valve
The valve is mounted at the bottom. This valve is used to change the oil. When opened, gravity causes the oil to run down.
Advantages of Crankcase
- The crankcase surrounds the connecting rod and crankshaft to prevent damage from dirt.
- Prevents dirt from entering the crankshaft and connecting rod.
- For complex engines, it helps to circulate the oil.
- It also functions as a pressure chamber for the air-fuel mixture.
- This part of the motor provides a sealed enclosure that keeps rotating components out of moisture and dirt.
Wrapping Up
The crankcase is a central component of the combustion engine and contains a functional group of crank mechanisms that connect and form a system boundary that seals the combustion engine from the outside. Prevents coolant and lubricating oil from leaking and moisture and dirt from entering.
Faqs
No, it is important to use the oil recommended by the manufacturer for your specific engine. Different engines require different types of oil with specific viscosity and additives to ensure proper lubrication and performance. Consult your vehicle’s owner’s manual or speak to a professional mechanic to determine the appropriate oil for your crankcase.
Inspecting the crankcase for cracks or damage can be challenging, as it is often hidden within the engine block. However, signs of a cracked or damaged crankcase may include oil leaks, excessive oil consumption, unusual engine noises, or a drop in engine performance. If you suspect a problem with the crankcase, it’s best to have it inspected by a qualified mechanic.
A crankcase breather filter is designed to filter the air that enters the crankcase ventilation system. It helps prevent contaminants, such as dirt, debris, and pollutants, from entering the engine and potentially causing damage. Regularly inspect and replace the crankcase breather filter according to the manufacturer’s recommendations to maintain optimal engine performance.
In most cases, a damaged crankcase cannot be effectively repaired and requires replacement. The crankcase is a crucial structural component of the engine, and any damage to it can compromise the engine’s integrity and performance. If you suspect a damaged crankcase, it’s best to consult a professional mechanic to evaluate the extent of the damage and recommend the appropriate course of action.
Yes, the crankcase plays a vital role in determining the engine’s oil capacity. The size and design of the crankcase will dictate the volume of oil required to properly lubricate the engine’s moving parts. It’s important to adhere to the manufacturer’s recommended oil capacity to ensure adequate lubrication and prevent potential engine damage. This information can typically be found in the vehicle’s owner’s manual or by consulting a mechanic.