The following are the key takeaways from this article:
- The camshaft is an important engine component that assists in opening and closing the valve with the movement of the crankshaft.
- The important parts of the camshaft include cam-bearing journals, bearing shells, lobes, chain sprockets, thrust plates, and woodruff keys.
- Some common problems in the camshaft include lobe wear, lifter tapping, backing cylinders, and camshaft popping.
- Common bad engine camshaft symptoms include engine cylinder misfire, tapping sounds, metal debris in the engine oil, black exhaust smoke, and check engine light.
- The cost to resolve the camshaft issues can be as low as $50 to replace the faulty bearing and as high as $3000 to replace the faulty camshaft.
An internal combustion engine operates when the inlet valve opens, injecting a fuel stream and air into the cylinder through the intake manifold. First, however, the valve must open in synchronization with the crankshaft gear (1).
The automakers use a timing belt to synchronize the motion of the camshaft and crankshaft. This article will shed light on other functions, history, problems, and symptoms of a bad camshaft.
History of Camshaft
The camshaft is an important part of the engine and was first designed in 1206 by Al Jazari. Al-Jazari employed this part in the water machine, which converts the rotatory motion into straight motion (3). Later in the 8th century, this part was implemented in automotive vehicles. It was found that the crankshaft rotating motion was converted into linear motion with the help of the valve gears (1). The camshaft is present in the internal combustion chamber.
Function of Camshaft
The camshaft is the most critical component; its main function is to operate the exhaust valves. The camshaft helps in opening and closing the exhaust valves. The valves in the combustion chamber allow the air and fuel to enter the chamber, and the valves allow the harmful gases to release from the gas chamber. The camshaft detects the requirement of the air and fuel in the chamber (3). Thus, it opens the valve at precise timings, so it can be concluded that the camshaft depends on timings.
Parts of a Camshaft
Although the name camshaft suggests that this component will have two major components cams and a shaft. In reality, a camshaft has certain small components that play an important role in its functioning. Some major parts of the camshaft are briefly discussed below:
Cam Bearing Journals
With the crankshaft movement, the camshaft rotates, opening and closing the engine valves in a synchronous motion (1). So, cam-bearing journals are used to change the rotary motion to the linear motion of the valves.
The bearing shells are exactly mounted on the cam bearing journals that help the camshaft rotate smoothly. So, the engine block is prevented from wear and tear using the bearing shells.
Another important component of a camshaft is the lobes that work to open/close the valves. For example, the inlet valve opens for air-fuel mixture intake for combustion and closes for the combustion process. Similarly, the exhaust valve opens to exhaust the gases.
The timing belt is used in the engine to synchronize the camshaft’s motion with the crankshaft’s movement. In addition, a chain sprocket set is attached at the side of the engine, where the crankshaft is located (1).
Thrust plates are attached at the engine’s back end to alleviate the play between the camshaft and the timing belt. These plates are mounted on the front side of the engine (5). Some thrust plates are mounted at the backside of the engine to support the rotary cams at the rear of the engine.
A woodruff key is a semi-circular machine shaft that prevents the cams from moving independently. A woodruff key is usually made up of cast iron or cold steel alloys.
Common Problems in Camshaft
Due to this error, the oil and fuel are not supplied to the engine on time, and harmful gases are not released. These harmful gases are deposited in the engine walls, and as a result, the efficiency of the engine is impacted (2). In addition, the condition of the lobe wear occurs when the lubrication process is slowed down and oil is not supplied to the camshaft parts (1). Thus, the engine performance is impacted badly, and the engine will fail to accelerate at high rpm. This happens because the valve will only open once a high rpm is supplied. Also, there are chances of misfiring in the engine cylinders, and harsh sound may observe due to the damaged camshaft.
Lifter tapping may occur for three reasons, i.e., bad oil in the engine, defective lifters, and bent rods in an engine. Overall, this affects the engine’s performance as the damaged rods and the bad engine oil impact the combustion process (5). The air-to-fuel mixture in the engine is disturbed due to the delayed valve opening and closing. As a result, misfires can occur in the engine. This produces ticking noises in an engine, and sluggish behavior of the engine is observed (2). It is determined that the connection between the lifter and camshaft becomes weak when the wrong viscosity oil is used in the engine. If the oil’s viscosity is thick, the oil will not smoothly pass through the valve lifters, and the engine’s rpm is not maintained.
The sound is produced when the rod becomes too hard and is unable to move properly. Thus, the performance of the engine becomes poor.
Backfiring and Popping
Thus, the gases do not enter the combustion chamber when the camshaft gets damaged. As a result, the air-to-fuel ratio in the engine is delayed, and the spark needs to be ignited on time. This result causes a backfire in the cylinders (2). As a result, the exhaust gases are not released at particular times, and black-colored smoke is released later. This smoke has a rotten egg smell due to the deposition of Sulphur and nitrogen in the combustion chamber. Thus, the engine’s performance becomes poor, and the car cannot accelerate at high speed because the spark’s ignition is delayed. Also, the engine check light is illuminated as a warning signal to avoid accidents later. All these issues occur due to broken camshafts as the valves operating differs due to lack of movement.
Common Symptoms of a Bad Camshaft
Following are some common symptoms of a bad camshaft:
Engine Cylinder Misfire
As the camshaft plays a role in timing the opening of inlet and outlet valves, a bad camshaft will result in either a lean or rich condition in the cylinder. The cylinder misfire can be noted by a missing engine or an engine providing low power (3). To further analyze the particular misfiring cylinder, you can connect a hand code reader with the OBDII module of your vehicle that will illustrate an OBDII fault code. This can be further decoded to analyze the particular misfiring cylinder.
Loud Tapping Sound
Another symptom of a bad camshaft is a loud tapping sound while driving. The tapping sound may disappear after driving a few miles after the engine components are lubricated. These tapping sounds indicate failure/problems in the lobes. After driving the vehicle for several years, the cam lobes often wear out, resulting in a tapping sound during cam operation. You are recommended to replace the cam lobes at the earliest in case of a tapping sound to avoid any further engine damage.
Metal Debris in the Engine Oil
Another indication of a bad camshaft can be metal debris in the engine oil. When a camshaft malfunctions, metal pieces can be scrapped off the components due to wear and tear. These pieces can be added to the engine oil reservoir (3). Dipping the stick in the engine oil reservoir cannot check the metal debris. However, when draining out the oil, you can analyze the oil for metal debris.
Black Smoke out of Exhaust
Another sign of a bad camshaft is the black smoke from the exhaust tailpipe. It can be due to the rich/lean condition in the engine cylinder due to malfunctioned camshaft movement (4). Black smoke usually indicates that the engine is burning more fuel and requires immediate service before eventual engine damage.
Check Engine Light
Although, the check engine light is an overall indication that some engine component is malfunctioning. You can connect a hand-code reader with the OBDII module to check which engine component is malfunctioning. In case of a camshaft malfunctioning, it is recommended to replace the malfunctioning camshaft component/the camshaft for optimum engine performance.