BOOK 1; VOLUME 4 (EXTRA)
Define the term valve float.
A condition in which weakened valve springs or excessive engine speed causes the valves to remain partially open.
A hybrid vehicle cooling system removes heat from what three main electric powertrain components?
- HV battery. - HV PCM. - Motor-generator.
List four common lubrication system problems.
- High oil consumption. - Low oil pressure. - High oil pressure. - Defective indicator or gauge.
Explain the difference between friction and antifriction bearings.
- Friction bearing have two smooth surfaces sliding on each other - Antifriction bearings use balls or rollers to avoid sliding action between the bearing surfaces.
List seven common causes of low engine oil pressure.
- Low oil level. - Worn connecting rod or main bearings. - Thin or diluted oil. - Weak or broken pressure relief valve spring. - Cracked or loose oil pump pickup tube. - Worn oil pump. - Clogged oil pickup screen.
Do not disconnect _____ or _____ lines unless absolutely necessary.
- Power steering. - Air conditioning.
List four functions of antifreeze.
- Prevents winter freeze up. - Prevents rust and corrosion. - Lubricates the water pump. - Cools the engine.
There are three basic types of engine oil pumps: _____, _____, and _____ types.
- Rotary. - Gear. - Vane.
Why is an oil cooler sometimes used?
An oil cooler may be used to help lower and control the operating temperature of the engine oil. Oil coolers are frequently used on turbocharged engines or for heavy-duty applications.
An oxygen sensor will not alter its output signal fast enough to maintain an efficient air-fuel ratio. Technician A says the sensor is shorted. Technician B says the sensor is lazy. Who is right?
B only.
Technician A says that catalytic converter problems are commonly caused by contamination. Technician B says that catalytic converter problems are often caused by extended service. Who is right?
Both A and B.
Some overhead camshaft engines have a(n) _____ that holds the cam followers and camshaft(s).
Camshaft housing.
Oil dye is sometimes added to motor oil to _____.
Detect leaks.
How does engine oil protect parts from excess wear?
Engine oil reduces friction and keeps moving parts in an engine from making direct contact.
A(n) _____ is a testing instrument that measures the chemical content of the engine exhaust gases.
Exhaust gas analyzer.
Why is a radiator shroud used?
It helps ensure that the fan pulls air through the radiator. Without it, the engine could overheat.
Upon encountering an uncommon high oil pressure problem, Technician A says its cause is low oil viscosity. Technician B says the cause is low relief valve spring tension. Who is right?
Neither A nor B.
_____ is the small space between moving engine parts for the lubricating oil film.
Oil clearance (bearing clearance).
Which of the following separates engine parts to prevent metal-on-metal contact?
Oil film.
A cooling system _____ test uses a hand-operated air pump to find leaks in the system.
Pressure.
When preparing to remove an engine from a vehicle, why are the components underneath the engine usually disconnected first?
So that oil, fuel, and coolant are not leaking out from the disassembled top end while working under the engine.
How is a block heater helpful with a diesel engine?
The block heater keeps the engine warm when the vehicle is not being used. It can be helpful with diesel engines because diesel engines are harder to start in cold weather.
Define the term smog.
The term is derived from the words "smoke" and "fog". it is formed when airborne pollutants combine with oxygen, nitrogen, and other elements in the presence of sunlight.
To check for exhaust manifold _____, use a straightedge and a flat feeler gauge.
Warpage.
When a thermostat is closed, which of these permits coolant circulation through the engine?
- Bypass hose. - Bypass valve.
What are typical gasoline engine and diesel engine compression readings?
- Gasoline engine: 125 - 200 psi (860 - 1400 kPa). - Diesel engine: 275 - 400 psi (1900 - 2750 kPa).
Oil _____, also called oil _____, is the thickness or fluidity of the motor oil.
- Viscosity. - Weight.
What are the three basic sources of vehicle emissions?
1.) Engine crankcase blowby fumes. 2.) Fuel vapors. 3.) Engine exhaust gases.
Technician A says that an engine's timing belt should be replaced during a major engine rebuild. Technician B says that an engine's cylinder head(s) should be inspected and reconditioned as needed during a major engine rebuild. Who is right?
Both A and B.
Why should you label wires and vacuum hoses when they are disconnected?
To simplify reconnection during engine installation assembly.
List five general rules to remember during engine assembly.
- All parts and tools should be perfectly clean and organized. - Select-fit engine parts must be reinstalled in their same location. - Lubricate engine parts thoroughly with a higher-than-normal viscosity oil. - Make sure engine bolts and nuts are not mixed together; additionally, check bolt lengths. - Keep components covered until you are ready to assemble them. - Torque all engine fasteners properly to specifications. - Inspect everything one last time as you install engine components. - Do not rush your work. - Avoid talking to anyone while working on an engine. - Refer to service manual if in doubt about any service task.
List seven items to look for when performing a visual inspection on a cooling system.
- Coolant leaks. - Loose or missing fan belt. - Low coolant level. - Abnormal water pump noises. - Leaves and debris covering the outside of the radiator. - Coolant in the oil (oil looks white and milky). - Combustion leakage into the coolant (air bubbles in coolant).
List five reason that HC readings can be higher than normal.
- Fuel system malfunction. - Improper ignition timing. - Engine problems. - Faulty emission control system. - Ignition system troubles. - Computer control system problems.
What are the main functions of a lubrication system?
- Reduce friction and wear between moving parts. - Help transfer heat away from engine parts. - Clean the inside of the engine by removing contaminants. - Cut power loss and increase fuel economy. - Prevent internal engine parts from rusting and corrosion. - Absorb shocks between moving parts to quiet engine operation and increase engine life.
What is the difference between two-, four-, and five-gas exhaust analyzers?
- The two-gas exhaust analyzer can measure hydrocarbons and carbon monoxide but cannot accurately analyze the exhaust gases from new engines. - The four-gas exhaust analyzer can measure hydrocarbons, carbon monoxide, carbon dioxide, and oxygen. - The five-gas exhaust analyzer measures hydrocarbons, carbon monoxide, carbon dioxide, oxygen, and oxides of nitrogen.
What are the problems resulting from camshaft lobe wear?
- Valve train clatter. - Reduced valve lift. - Poor engine performance.
List and explain the four kinds of vehicle emissions.
1.) Hydrocarbons - A form of emissions resulting from the release of unburned fuel into the atmosphere. 2.) Carbon monoxide - An extremely toxic emission resulting from the release of partially burned fuel. 3.) Oxides of nitrogen - Emissions produced by extremely high temperatures during combustion. 4.) Particulates - Solid particles of carbon soot or ash and fuel additives that blow out of a vehicle's tailpipe.
What are the four functions of a cooling system?
1.) Remove excess heat from the engine. 2.) Maintain a constant engine operating temperature. 3.) Help a cold engine quickly reach operating temperature. 4.) Proved heat for the passenger compartment.
List the four functions of a radiator cap.
1.) Seals the top of the radiator filler neck to prevent leakage. 2.) Pressurizes the system to raise the boiling point of coolant. 3.) Relieves excess pressure to protect against system damage. 4.) Allows coolant flow between the radiator and the coolant reservoir (in closed systems).
List and explain the five major parts of a cooling system.
1.) Water pump - Forces coolant through the engine and other system parts. 2.) Radiator hoses - Connect the engine to the radiator 3.) Radiator - Transfers engine coolant heat to outside air. 4.) Fan - Draws air through the radiator. 5.) Thermostat - Controls coolant flow and engine operating temperature.
An engine's operating temperature is usually between _____.
180*F and 210*F.
On a freshly rebuilt engine, oil consumption during the first _____ miles is not unusual.
2000.
Technician A says that leaking valve stem seals will cause the engine to emit blue smoke after initial starting. Technician B says that the cylinder head must generally be removed to replace the valve stem seals. Who is right?
A only.
Technician A says that the camshaft bearing caps in an OHC engine must be installed in their original location. Technician B says that the camshaft bearings in an OHC engine may be a pressed-in, two-piece design. Who is correct?
A only.
Tests find a burned engine valve. The engine is not smoking and has good oil pressure. Technician A says that this should be an in-vehicle operation; the block can remain bolted to the chassis. Technician B says that the engine must be removed from the vehicle to service the valves. Who is right?
A only.
While discussing the operation of the evaporative emissions control system, Technician A says a charcoal canister stores fuel vapors when the engine is not running. Technician B says the canister absorbs fuel vapors only when the engine is running. Who is right?
A only.
Why is a wet compression test helpful?
A wet compression test helps determine which engine parts are causing the problem when any cylinder pressure is reading below specifications.
Why is an oil filter very important to engine service life?
An oil filter removes small metal, carbon, rust, and dirt particles from the engine oil. It protects the moving engine parts from abrasive wear. Decomposed oil results from excess heat and mechanical stress. The oil actually changes from a liquid to a solid, "chocolate pudding-like" substance.
Oil changes are being discussed. Technician A says that used motor oil should be drained into the sewer system for disposal. Technician B says that it is recommended that individuals driving turbocharged or supercharged engines change their vehicle's oil in shorter intervals than a naturally aspirated engine. Who is right?
B only.
Positive crankcase ventilation systems are being discussed. Technician A says that automakers use open PCV systems in late-model vehicles. Technician B says that PCV systems reduce air pollution and prevent engine damage caused by blowby gas buildup. Who is right?
B only.
Supercharger cooling system are being discussed. Technician A says that hot air carries more oxygen for combustion than an equal amount of cooler air. Technician B says that such a system often uses its own electric pump, hoses, and radiator to pump cool antifreeze through the supercharger intercooler. Who is right?
B only.
Technician A says a gasoline engine compression gauge can be used to perform a compression test on a diesel engine. Technician B says a gasoline compression gauge should not be used to perform a diesel engine compression test. Who is right?
B only.
Technician A says that a transmission or transaxle should hang unsupported after engine removal. Technician B says that on some vehicles, the engine is removed from below by raising the vehicle and lowering the engine out from under the frame. Who is right?
B only.
Technician A says that you should use sealer on the oil pump gasket. Technician B says that the oil pump should be primed before installation. Who is correct?
B only.
A driver complains that her oil pressure warning light flickers on and off at stoplights. Technician A says that the oil level in the engine should be checked. Technician B says that the indicator light circuit could also be at fault. Who is correct?
Both A and B.
Technician A says a 50/50 mix of antifreeze and water is commonly used to provide protection for most weather conditions. Technician B says that minimum coolant strength should be several degrees lower than the lowest normal temperature for the climate of the area. Who is right?
Both A and B.
Technician A says that valve float can be caused by hydraulic lifter problems. Technician B says that valve float can be the result of weak valve springs. Who is right?
Both A and B.
While discussing oil pump driven methods, Technician A says an oil pump can be directly engaged to and powered by the crankshaft snout. Technician B says an oil pump can be driven by a cogged belt. Who is right?
Both A and B.
While discussing thermostat service, Technician A says a stuck thermostat can cause engine overheating. Technician B says a stuck thermostat can cause engine overcooling. Who is right?
Both A and B.
How do you measure actual engine oil pressure?
By installing a pressure gauge into the sending unit or oil pressure sensor. This entails removing the engine oil sending unit from the engine. After attaching the oil pressure test gauge, start and warm the engine, running it at the specified rpms. Read the test gauge at idle and note the oil pressure at both low and high engine speeds, comparing the readings.
A(n) _____ test checks for the presence of combustion gases in the engine coolant, indicating an engine problem.
Combustion leak.
When lifting an engine from a vehicle, make sure the _____ is centered over the engine.
Crane boom or engine hoist.
An air injection system forces fresh air into the _____ of the engine to reduce HC and CO emissions.
Exhaust ports or catalytic converter.
A cooling system should be _____ when rust or scale is found in the system.
Flushed.
A(n) _____ can be used to pinpoint test a digital EGR valve and check the condition of the EGR windings.
Handheld scope/oscilloscope.
The valve train clearance on an engine with _____ lifters can be adjusted with the engine off or with the engine running.
Hydraulic.
Describe the results of a clogged catalytic converter.
Increased exhaust system back pressure. Engine performance is decreased because gasses cannot flow freely through the converter.
The emission control _____ gives important instructions, diagrams, and specifications for complying with EPA regulations.
Information sticker.
What is the purpose of the OBD II drive cycle?
It is designed to tell the technician whether the OBD II system is operating properly.
EGR system service is being discussed. Technician A says that an EGR valve stuck open will cause a rich air-fuel mixture. Technician B says that a pinpoint test on a digital EGR valve means hooking the vehicle up to an exhaust gas analyzer. Who is right?
Neither A nor B.
_____ are the solid particles of carbon soot that exit a vehicle's tailpipe. They are more of a problem in diesel engines.
Particulates.
A(n) _____ system uses engine vacuum to draw toxic blowby gases into the intake manifold for burning in the combustion chambers.
Positive crankcase ventilation (PCV).
What is the purpose of priming the oil pump?
Priming will help protect the pump and ensure full engine oil pressure sooner on initial starting of the engine.
A(n) _____ is sometimes needed to remove a vibration damper, seal, or crankshaft sprocket.
Puller.
Used torque-to-yield head bolts must be _____ when the engine is reassembled.
Replaced.
The highest API oil service rating for gasoline engines is _____.
SN.
What can happen if you remove a radiator cap with the coolant at operating temperature?
The pressure release can make the coolant begin to boil and expand into steam vapor. Boiling coolant could spurt out of the filler neck, causing sever burns.
How does an automatic transmission oil cooler work?
The transmission oil cooler is a small tank enclosed in one of the main radiator tanks. Since the transmission fluid is hotter than the engine coolant, heat is removed from the fluid as it passes through the radiator and cooler.
Why should an engine be warmed to full operating temperature before its oil is changed?
This will help suspend debris in the oil and make the oil drain more thoroughly.
How can you quickly determine if a dash temperature gauge is functioning.
To quickly test a temperature gauge, disconnect the wire going to the temperature gauge sending unit. Using a jumper wire, ground the gauge wire to the engine block. Then, turn the ignition key switch on and watch the temperature gauge. It will normally swing to hot when the wire is grounded. It should return to cold when the wire is ungrounded.
Why is a mini catalytic converter sometimes used?
To reduce emissions during engine warm up.
Why should most parts be returned to their original locations in an engine?
Wear patterns and select-fit parts (from factory) require that most components be installed in their original locations.
How do you check the general operation of a PCV valve with your finger and with an exhaust gas analyzer?
With the engine idling, place your finger over the end of the valve. With airflow stopped, you should feel suction on your finger, and the engine idle speed should drop about 40-80 rpm. Using a four- or five-gas exhaust analyzer, measure and note the analyzer readings with the engine idling. Then, pull the PCV valve out of the engine, but not off the hose. Compare the reading after the PCV valve is removed.
