Question 1

About how much of the turning torque applied to a head bolt is lost to friction?

Accepted Answer

Approximately 80% of the turning torque applied to a head bolt is lost to friction, primarily due to the friction between the bolt threads and the surface, as well as under the bolt head.

Question 2

Service information states SAE 30 engine oil should be used on the threads of the head bolts, before installation and torquing. Technician A says that SAE 5W-30 will work. Technician B says that SAE that 10W-30 will work. Who is right?

Accepted Answer

The specific recommendation of SAE 30 engine oil for the threads of the head bolts is likely due to its viscosity and properties at the temperature range expected during operation and installation. SAE 5W-30 and 10W-30 have different cold weather viscosity ratings and may not provide the same performance or protection as SAE 30, especially under the specific conditions for which the recommendation was made. Therefore, neither Technician A nor Technician B is correct in suggesting alternatives.

Question 3

Technician A says that the torque applied to the head bolts is the same as the clamping force on the gasket. Technician B says that the clamping force is the force actually applied to the surfaces of the gasket. Who is right?

Accepted Answer

Technician B is correct because the clamping force refers to the force exerted by the head bolts that actually holds the gasket in place, ensuring a proper seal between the mating surfaces. This force is not necessarily the same as the torque applied to the bolts, as torque is the measure of the twisting force required to spin the bolt, not the force that directly compresses the gasket.

Question 4

A coating often used to keep an engine from rusting during assembly is called ________.

Accepted Answer

Fogging oil is specifically designed to protect the internal surfaces of engines from rust and corrosion, especially during periods of inactivity or storage, making it the correct choice for a coating used during assembly to prevent rusting.

Question 5

Head gasket installation is being discussed. Technician A says that the surface finish of the cylinder head or block deck is very important for proper sealing to occur. Technician B says that if "front" is marked on a head gasket, the mark should be installed near the accessory drive belt end of the engine. Who is right?

Accepted Answer

Both technicians are correct. The surface finish is crucial for a proper seal, and orientation marks like "front" indicate how the gasket should be installed relative to the engine layout.

Question 6

Technician A says that studs should be installed finger tight. Technician B says that studs must be installed using a thread locker such as Locktite. Which technician is correct?

Accepted Answer

Studs should be installed finger tight to ensure they are properly seated without over-tightening, which could damage the threads or the part. Using a thread locker like Loctite is also recommended to prevent the studs from loosening due to vibration or thermal expansion and contraction, ensuring a secure and lasting fit.

Question 7

What can be used to check that the heads are at the correct angle for the intake manifold on a V-type engine?

Accepted Answer

An angle gauge is used to ensure that the heads are aligned at the correct angle for the intake manifold on a V-type engine, ensuring proper fitment and function.

Question 8

Which of these is TRUE about checking bearing clearances using Plastigage?

Accepted Answer

Plastigage is used to measure the clearance between bearing surfaces by placing a strip of Plastigage material on the journal, then installing and torquing the cap to factory specifications. The material flattens out, and its width after being compressed indicates the clearance. For accurate measurements, the journal and bearing surfaces must be clean and free of oil.

Question 9

An engine dynamometer measures ________.

Accepted Answer

The answer of An engine dynamometer measures ________.
...

Question 10

If the torque and horsepower readings are graphed, where do the curves cross (equal each other)?

Accepted Answer

The curves for torque and horsepower on a graph cross at 5,252 RPM due to the mathematical relationship between them. Horsepower is calculated from torque and RPM, with the constant 5,252 being a factor in the equation (Horsepower = (Torque x RPM) / 5252), making them equal at this specific RPM.

Question 11

What can happen if gasket surfaces are too smooth?

Accepted Answer

If gasket surfaces are too smooth, the gasket may not have enough friction to stay in place, potentially moving out of its proper location and causing leaks.

Question 12

Technician A says that glues are used to help gaskets seal. Technician B says that deburring all sharp edges is an important step that has to be done to achieve proper engine assembly. Who is right?

Accepted Answer

The answer of Technician A says that glues are used...

Question 13

What would happen if oil or water (coolant) was at the bottom of a dry hole in the bolt when the head bolts are installed and torqued?

Accepted Answer

The answer of What would happen if oil or water...

Question 14

Two technicians are discussing the torqueing procedure for head bolts. Technician A says that they should be tightened starting at the center of the head and working toward the ends. Technician B says that they should be tightened in three steps or according to the factory specified manner if torque-to-yield or torque-angle. Who is right?

Accepted Answer

Both technicians are correct. Technician A is right because starting at the center and working outward in a spiral pattern is a common method for ensuring even clamping force across the head, which is crucial for maintaining a good seal. Technician B is correct because using a stepped approach or following the manufacturer's specifications, especially for torque-to-yield or torque-angle specifications, is essential for achieving the correct preload on the bolts without over or under-tightening.

Question 15

Technician A says that the back of all engine bearings should be lubricated during assembly. Technician B says that the face of the main and rod bearings should be lubricated before final assembly. Who is right?

Accepted Answer

The face of the main and rod bearings should be lubricated before final assembly to ensure proper operation and prevent damage. The back of engine bearings should not be lubricated as they need to be dry to properly seat and transfer heat.

Question 16

Engine pre-oiling is recommended for which of these reasons?

Accepted Answer

Filling the oil passages with oil prior to initial start-up ensures that the engine is properly lubricated from the moment it starts, preventing dry running and reducing wear.

Question 17

For high performance use, most experts recommend the use of ________ instead of standard bolts.

Accepted Answer

The answer of For high performance use, most experts recommend...

Question 18

An engine block is being fitted with studs. Technician A says that the tightening torque in the installation instructions is for the stud and not the nut. Technician B says that if a thread locker is used, be sure to immediately install the main bearing caps before the compound cures to help avoid misalignment. Who is right?

Accepted Answer

The answer of An engine block is being fitted with...

Question 19

Technician A says to be sure the piston notch "front" or arrow points toward the front of the engine. Technician B says to be sure that the piston ring gaps all line up before installing the piston.. Who is right?

Accepted Answer

Technician A is correct because the piston notch "front" or arrow is typically used to indicate the orientation of the piston towards the front of the engine for proper installation. Technician B is incorrect because piston ring gaps should not line up; they should be staggered around the circumference of the piston to prevent compression leaks.

Question 20

Technician A says that all oil galleries must be thoroughly cleaned before engine assembly can begin. Technician B says that all expansion cups and plugs should be installed with a sealer to prevent leaks. Who is right?

Accepted Answer

Both technicians A and B are correct. Cleaning oil galleries is crucial to prevent blockage and ensure proper lubrication throughout the engine. Installing expansion cups and plugs with a sealer is standard practice to prevent leaks.

Quiz 37: Engine Assembly and Dynamometer Testing