Question

17 multiple choice 1 point
what is the compression ratio of an engine if the volume of the cylinders at tdc is 13cc and 143 cc at bdc?
9:1
11:1
10:1
10.7:1
18 multiple choice 1 point
a customer states that their car overheats while driving however the issue only occurs when the car is at a stoplight. what is the most likely cause?
stuck closed thermostat.
a faulty head gasket.
a faulty cooling fan.
low coolant.

Explanation:

Step1: Calculate compression ratio

Compression ratio formula: $\frac{V_{BDC}}{V_{TDC}}$. Given $V_{TDC} = 13$ cc and $V_{BDC}=143$ cc. So, $\frac{143}{13}$.

Step2: Simplify the ratio

$\frac{143}{13}=11$.

Step1: Analyze each option

• Stuck - closed thermostat: Would cause overheating all the time, not just at stop - lights.
• Faulty head gasket: Usually causes other symptoms like coolant in oil or vice - versa, not specifically overheating at stop - lights.
• Faulty cooling fan: When the car is moving, air flow can help cool the engine (like natural cooling). But at stop - lights, without the fan (if it's faulty), there's no forced air flow, so overheating occurs.
• Low coolant: Would cause overheating in various driving conditions, not just at stop - lights.

Answer:

11:1