Chapter 7 Flashcards
Why are regular engine oil changes essential in the Middle East?
The hot climate stresses engines more.
Even though special oils are designed for high temperatures, regular oil changes are still necessary for engine health and performance.
What is the purpose of a car’s cooling system?
To cool the engine and maintain the correct operating temperature.
It uses a coolant mixture of ethylene glycol and water also to prevent rust inside the engine.
What happens if the water pump belt is loose or broken?
The belt drives the water pump to maintain proper coolant flow.
If it’s loose or broken, coolant flow is disrupted → leading to engine overheating.
What should you do if your engine overheats?
Wait until the engine cools to about 90°C.
Change the cooling fan fuse
Top up with hot water (never cold water!)
⚠️ Cold water in a hot radiator can cause the cylinder block to crack.
What should you do when driving up a steep hill?
Turn off the A/C or climate control
Helps prevent engine overheating
Provides extra power to help climb the hill
What are the three grades of unleaded gasoline sold in the UAE and what do octane numbers mean?
Grades of Unleaded Gasoline in UAE:
“E Plus” Red – 91 Octane
“Special” Green – 95 Octane (suitable for all cars)
“Super” Blue – 98 Octane (for high-performance cars)
📌 Octane Number:
Measures fuel’s anti-knocking performance (resistance to engine knocking).
What are the signs of a damaged exhaust system?
Signs of a faulty exhaust:
Unusual noises (loud rumbling)
Vibrations in the steering wheel or seat
Decreased fuel efficiency
The smell of exhaust fumes inside the car
May lead to carbon monoxide leaks
What is the purpose of a catalytic converter?
Catalytic Converter:
Reduces toxic emissions from engine exhaust
Converts harmful gases like:
Carbon monoxide (CO)
Nitrogen oxides (NOx)
Hydrocarbons (HC)
➡️ Into safer gases like carbon dioxide (CO₂), nitrogen (N₂), and water vapor
What type of fuel must be used in cars with catalytic converters?
Only use unleaded petrol
Leaded petrol damages the catalytic converter
Unleaded fuel ensures the converter can effectively reduce harmful emissions
🚫 Using the wrong fuel can destroy the converter and increase pollution
What is the purpose of the clutch in a car?
The clutch connects and disconnects the engine from the transmission system.
When the clutch pedal is pressed, power flow to the drive wheels stops (decoupled).
When released, power from the engine is transmitted to the wheels again.
💡 It allows smooth gear changes and prevents stalling.
What’s the difference between manual and automatic gearboxes?
- Manual Gearbox
Has 5 or more gears.
Requires clutch pedal to change gears.
Driver manually selects gear for speed range.
- Automatic Gearbox
No clutch pedal.
Gear shifting happens automatically based on speed.
Becoming more common in modern vehicles.
What are the two types of brake systems in a car?
- Main Brake (Foot Brake)
Acts on all four wheels
Hydraulically operated
- Parking Brake (Handbrake)
Used to keep the car stationary
Mechanically operated
What is the servo-controlled braking system in a car?
It’s a booster system that amplifies the force applied by the driver on the brake pedal, making it easier to stop the car with less effort.
What is the function of ABS (Anti-lock Braking Systems) in a car?
ABS prevents the wheels from locking during hard braking, helping the driver maintain steering control and stability in emergencies.
If the system fails, a yellow warning light appears on the dashboard.
What are TWI markings on a tyre and what do they indicate?
TWI (Tread Wear Indicators) are raised rubber bars found around the tire’s rim.
When the main tread wears down to the same level as the TWI, the tire is considered bald and must be replaced.
New tyre tread = 9 mm
Reduced grip begins at 3 mm tread depth
What is the main cause of excess wear and tear on tires?
Wrong wheel alignment is the main cause.
Routinely checking and correcting your wheel alignment helps ensure longer tire life and safer driving.
