Quiz 13 - Engine Sealing And Reassembly

Gaskets, seals, and O-rings all perform the vital task of sealing the engine. Gaskets are used to create a tight seal between two or more engine components, preventing leaks of fluids or gases. Seals are used to prevent the leakage of fluids or gases between stationary and moving parts of the engine. O-rings are specifically designed to create a seal in a circular groove, preventing leaks in various engine components. Therefore, all of these components are essential for maintaining the integrity and efficiency of the engine's sealing system.

Both Technician A and Technician B are correct. Technician A is correct because some seals are indeed designed to keep oil from escaping around a rotating shaft. These seals are commonly known as shaft seals or oil seals and are used in various applications such as engines, gearboxes, and pumps. Technician B is also correct because some seals are used to prevent fluid leaks between two fairly rigid flanges. These types of seals are commonly referred to as gaskets and are used in applications where two flanges need to be sealed tightly to prevent fluid leakage, such as in pipelines and plumbing systems.

A silicone RTV gasket can be used to replace conventional gaskets made of paper, cork, or cork with rubber. Silicone RTV gaskets are versatile and can be used as a substitute for different types of gaskets depending on the specific application requirements. They provide a reliable seal and are resistant to high temperatures, chemicals, and weathering. Therefore, they are a suitable alternative to traditional gasket materials like paper, cork, or cork with rubber.

Both Technician A and Technician B are correct. Technician A is correct because damaged threads in a cylinder head can indeed be repaired with a helically coiled insert. This insert, also known as a thread insert or a helicoil, can be used to restore the integrity of the damaged threads. Technician B is correct because stripped threads are commonly caused by over-torquing, which can lead to the threads being pulled or stripped from the cylinder head. Therefore, both technicians are correct in their statements.

Technician B is correct. While Technician A's statement about smooth surfaces not requiring gaskets or sealants may be true in some cases, it is not always the case. Gaskets and sealants are used to ensure a proper seal between two surfaces, regardless of their smoothness. Technician B's practice of always using new gaskets and never reusing old ones is a good practice as gaskets can degrade over time and may not provide an effective seal if reused. Therefore, Technician B's approach is more reliable and recommended.

Bolt torque is a measure of the rotational force applied to tighten a bolt. It is influenced by tension, which is the stretching force on the bolt, as well as torsion, which is the twisting force. Friction also plays a role in determining bolt torque, as it affects the resistance to rotation. Therefore, all three factors - tension, torsion, and friction - contribute to the overall bolt torque.

A damaged bolt should be discarded because repairing it with a tap or a die may not fully restore its strength and integrity. A tap is used to repair damaged female threads, while a die is used to repair damaged male threads. However, if the bolt is significantly damaged or weakened, it is safer to discard it and replace it with a new one to ensure proper functionality and prevent potential failures or accidents.

Both Technician A and Technician B are correct. Torque-to-yield bolts are designed to provide a more uniform clamping force compared to conventional bolts. They are tightened to a specific torque and then rotated a certain number of degrees, which helps to achieve the desired clamping force. Therefore, both statements are accurate in describing the characteristics and installation process of torque-to-yield bolts.

Graphite is a natural lubricant because it has a layered structure with weak bonds between the layers. This allows the layers to slide over each other easily, reducing friction and providing lubrication. Additionally, graphite has low reactivity and high thermal stability, making it an effective lubricant in high-temperature and high-pressure environments.

Both Technician A and Technician B are correct. Technician A is correct because using soft gaskets on valve covers can help create a tight seal and prevent oil leaks. Technician B is correct because using soft gaskets on water pumps can also help create a tight seal and prevent coolant leaks. By using soft gaskets on both valve covers and water pumps, both technicians are taking the necessary steps to ensure proper sealing and prevent leaks in the respective components.

The statement "Cut bolt threads are 30 percent stronger than rolled threads" is not correct. In reality, rolled threads are generally stronger than cut threads. Rolled threads have a greater tensile strength and fatigue resistance due to the compressive forces applied during the rolling process, which helps to align the grain structure of the metal. Cut threads, on the other hand, can have uneven surfaces and may introduce stress concentrations, making them weaker compared to rolled threads.

Technician A is correct. Aluminum and cast iron do have different rates of thermal expansion. Aluminum expands more than cast iron when heated. Technician B's statement about cast iron having a coefficient of thermal expansion two or three times greater than aluminum is incorrect.

The exhaust manifold gasket is not used on certain engines because some engines do not have an exhaust manifold. The exhaust manifold is a component that collects exhaust gases from multiple cylinders and directs them into the exhaust system. Engines that do not have an exhaust manifold, such as some rotary engines or certain designs with integrated exhaust manifolds, do not require an exhaust manifold gasket.

The proper engine break-in procedure is best determined by the new car manufacturer. This means that the manufacturer of the new car is the most reliable source of information when it comes to how to properly break in the engine. They have the knowledge and expertise to provide specific instructions that will ensure the engine's longevity and optimal performance. It is important to follow the manufacturer's guidelines to avoid any potential damage or issues with the engine.

Both Technician A and Technician B are correct. Technician A is correct because spray painting the engine assembly after it is completely assembled helps to protect it from corrosion and adds a finishing touch to the engine. Technician B is also correct because putting grease on the exhaust and intake ports before painting the engine helps to prevent the paint from sticking to these areas and allows for easier cleaning and maintenance in the future.

Technician A is correct because using adhesives to hold gaskets in place during installation is a common and effective practice. RTV (Room Temperature Vulcanizing) sealants are not typically used when an anaerobic sealant is required, as they have different properties and applications. Therefore, Technician B is not correct in this scenario.

Neither Technician A nor Technician B is correct. The proper engine break-in procedure typically involves a combination of driving at varying speeds and loads to properly seat the piston rings and allow the engine components to wear in evenly. Running the engine at idle speed for two hours or accelerating at full throttle to 50 mph do not provide the necessary conditions for a proper break-in.

Technician A is correct. Chemical thread retainers are used on critical bolts and nuts to prevent them from loosening due to vibrations or other factors. They provide a strong and reliable hold, eliminating the need for lock washers. Therefore, chemical thread retainers can be used as a substitute for lock washers. Technician B is incorrect in stating that they cannot be used as a substitute.