Chapter 55 PowerPoint

Define these Technical Terms using the textbook:

1. black engine smoke

2. blue-gray engine smoke

3. compression test

4. connecting rod bearing knock

5. cranking balance test

6. crankshaft vibration damper

7. cylinder balance test

8. cylinder leakage test

9. engine blow by

10. engine vacuum leaks

Answer these discussion questions using the textbook:

1. List some common symptoms of engine mechanical problems.

Read the chapter summary below:

■ If a technician does not know how to properly diagnose (locate) engine problems, a great deal of time, effort, and money will be wasted.

■ After gathering information from the customer or service writer, inspect the engine using your senses (sight, smell, hearing, and touch).

■ Coolant in oil will show up as white or milky oil.

■ Oil-fouled spark plugs indicate internal oil leakage into the engine combustion chambers.

■ Engine blow by occurs when combustion pressure blows past the piston rings into the lower block and oil pan area of the engine.

■ Abnormal engine noises (hisses, knocks, rattles, clunks, and popping) may indicate part wear or damage.

■ A compression test is one of the most common methods of determining engine mechanical condition.

■ A wet compression test should be completed if cylinder pressure reads below specifications. It will help you determine what engine parts are causing the problem.

■ The compression gauge reading for a good cylinder will increase evenly to specifications. The gauge readings should not vary by more than about 10% from one cylinder to another.

■ Valve train problems can cause engine missing, oil consumption, blue-gray exhaust smoke, light tapping sounds from the upper area of the engine, rough idling, overall performance problems, and even cylinder and piston damage.

■ A worn timing chain will upset valve timing, reducing compression stroke pressure and engine power.

■ Worn rocker arms can cause valve clatter (light tapping noise) by upsetting valve clearance.

■ A blown head gasket can cause a wide range of problems: overheating, missing, coolant or oil leakage, engine smoking, and even head or block damage (burned mating surfaces).

■ Piston knock or slap is a loud metallic knocking sound produced when the piston flops back and forth inside its cylinder.

■ Worn piston rings or cylinders result in blow by, blue-gray engine smoke, low engine power, spark plug fouling, and other problems caused by poor ring sealing.

■ Connecting rod bearing knock is caused by wear and excessive rod bearing-to-crankshaft clearance.

■ Main bearing knock is similar to rod bearing knock but is slightly deeper or duller in pitch.