Quiz 3 - Upper Engine/Timing Components

Multiple valve engines tend to be more efficient than engines with two valves per cylinder because they allow for increased port areas, provide more valve area, and provide less restriction to the airflow. This means that the engine can intake and exhaust gases more effectively, leading to improved combustion and power output. Additionally, the increased valve area allows for better control of the air-fuel mixture, resulting in better fuel efficiency. Overall, having multiple valves per cylinder enhances the engine's performance and efficiency.

If a timing belt or chain breaks, the most likely engine damage would be bent valves. This is because the timing belt or chain is responsible for synchronizing the movement of the camshaft and the valves. If the belt or chain breaks, the camshaft stops rotating, and the valves may remain open when they should be closed. As a result, when the piston comes up, it can collide with the open valves, causing them to bend. This can lead to a loss of compression and engine performance.

Both Technician A and Technician B are correct. Technician A is correct in stating that timing chains typically are provided with splash lubrication. This means that the timing chain is lubricated by the oil splashing around inside the engine. Technician B is correct in stating that timing gears should always be replaced as a set. This is because the gears wear together and replacing only one gear can lead to uneven wear and potential timing issues.

Both Technician A and Technician B are correct. Worn valve stem seals can indeed increase oil consumption as they fail to properly seal the valve stems, allowing oil to leak into the combustion chamber. This leads to oil being burned along with the fuel, resulting in increased oil consumption. Additionally, worn valve stem seals can cause valve deposits as they allow oil to enter the combustion chamber and form carbon deposits on the valves. These deposits can hinder proper valve operation and lead to various engine problems.

The idler shaft sprocket typically would not have a timing mark because it is not directly involved in the timing of the engine. The idler shaft sprocket is responsible for maintaining tension on the timing belt or chain, but it does not need to be precisely timed with the other components. Therefore, it does not require a timing mark.

When a camshaft is worn to the point of replacement, both the valve lifters and timing drive components should be replaced. The camshaft and valve lifters work together to open and close the engine valves, and if the camshaft is worn, it can cause damage to the valve lifters. Additionally, the timing drive components, such as the timing belt or chain, are connected to the camshaft and are responsible for keeping the engine's valves and pistons in sync. If the camshaft is worn, it can also affect the timing drive components, leading to further engine damage. Therefore, both A (valve lifters) and B (timing drive components) should be replaced when the camshaft is worn.

A typical recommended timing belt change interval mileage is 60,000 to 100,000 miles. This means that it is generally advised to replace the timing belt of a vehicle within this mileage range to prevent potential issues or failures.

The typically acceptable maximum amount of warpage on an average cylinder head is .005 inch. This means that any warpage within this range is considered normal and does not pose a significant issue. Warpage refers to the deformation or bending of the cylinder head, which can affect its performance and sealing capabilities. Therefore, it is important to ensure that the warpage remains within acceptable limits to maintain the proper functioning of the cylinder head.

Neither Technician A nor Technician B is correct. Timing belts are not typically stretched into place using a pry bar. Instead, they are carefully installed according to the manufacturer's specifications, ensuring proper tension and alignment. Additionally, timing belts should not be lubricated as they are made of a special material that is designed to work without lubrication.

The most likely cause for all the hydraulic lifters being collapsed and causing valvetrain noise is low oil pressure. Hydraulic lifters rely on oil pressure to maintain proper functioning and prevent noise. If the oil pressure is low, it may not be able to adequately supply the lifters, causing them to collapse and create noise.

The camshaft rotates at half the speed of the crankshaft, not twice the speed.

Both Technician A and Technician B are correct. Checking camshaft wear requires measuring the dimensions accurately. Technician A uses a micrometer, which is a precision instrument used for measuring small distances or thicknesses. Technician B uses a dial indicator, which is also a precision instrument commonly used for measuring small distances or displacements. Therefore, both technicians are using appropriate tools to accurately measure camshaft wear.

When one hydraulic lifter is collapsed and causing valvetrain noise, the most likely cause is one worn or dirty lifter. This means that the lifter is either worn out or has accumulated dirt, preventing it from functioning properly. This can lead to a loss of oil pressure in that lifter, causing it to collapse and create the valvetrain noise. Low or high oil pressure, as well as incorrect valve timing, are less likely to be the cause of the issue.

Hydraulic lifters must have manually adjustable valves because they rely on oil pressure to maintain proper valve lash. The oil pressure is controlled by adjusting the valve clearance manually to ensure that the lifter operates correctly. Solid lifters, on the other hand, do not rely on oil pressure and therefore do not require manual adjustment. Therefore, the correct answer is hydraulic.