Chapter 07: Introduction

After studying this chapter, you should be able to:

LO 7-1 Identify and describe the purpose, operating, and regulatory factors influencing cylinder component design and construction.

LO 7-2 Classify pistons according to their application, design, construction features, and material.

LO 7-3 Identify and explain the purpose and functions of major piston construction features.

LO 7-4 Explain the purpose and methods for cooling engine pistons.

LO 7-5 Identify and explain the purpose and functions of piston rings, their construction features, and their ring shapes according to ring function.

LO 7-6 Identify and explain the purpose, function, and construction of piston pins.

LO 7-7 Identify and explain the purpose, function, and construction features of connecting rods.

LO 7-8 Explain the scope of cylinder component service and operating factors that accelerate cylinder wear.

LO 7-9 Outline diagnostic techniques used for evaluating the condition of a piston ring-to-cylinder wall seal.

LO 7-10 Outline techniques for connecting rod inspection and service.

An older truck arrives at your shop, and the driver complains that the engine lacks power and is running rough. During an inspection, you hear a knocking sound in the engine. There are many significant oil leaks from the gaskets and seals on the engine. A considerable amount of oil-laden blowby is being emitted from the road draft tube, leaving a large amount of oil on the vehicle frame. The engine oil level is low, and when the throttle is snapped to accelerate the engine, visible black and gray smoke is observed at the exhaust pipe. While the odometer reading is only 279,617 miles (450,000 kilometres [km]), the vehicle is close to 12 years old and is primarily used to pick up and deliver scrap metal in and around the city on a daily basis. Before you can prepare an estimate for the cost of repairs, you need to evaluate whether the base engine system is in satisfactory condition to justify any repairs or adjustments to the fuel system and other engine systems. As you prepare to make a service recommendation, consider the following questions:

1. What techniques would you use to estimate the remaining service life of the engine, and why would you recommend performing the work?
2. The accumulated distance on the odometer is relatively low for the engine to be worn out and in need of an overhaul. What factors could contribute to premature wear of this truck’s engine? What observations could you make that would support your answer?
3. If the engine is overhauled and the vehicle is returned to service, what operating recommendations would you make to the driver to extend the life of the engine?