Question

the upper radiator hose collapses when the engine cools. what is the most likely cause?
a defective upper radiator hose
the spring is missing from the upper radiator hose which is used to keep it from collapsing
a defective pressure cap
a defective thermostat
question 2
1 pts
what can be done to prevent air from getting trapped in the cooling system when the coolant is replaced?
pour the coolant into the radiator slowly.
use a coolant exchange machine that draws a vacuum on the system.
open the air bleeder valves while adding coolant.
either b or c
question 3
1 pts
which statement is true about thermostats?
the temperature marked on the thermostat is the temperature at which the thermostat should be fully open
thermostats often cause overheating
the temperature marked on the thermostat is a temperature at which the thermostat should start to open.
both a and b

Explanation:

Question 1

To determine the cause of upper radiator hose collapse on cooling, we analyze each option:

• A defective hose (Option A) is less likely as collapse on cooling relates to pressure/vacuum.
• Upper hoses typically don’t have springs (Option B is incorrect).
• A defective pressure cap (Option C) fails to maintain pressure, causing a vacuum when cooling, leading to hose collapse.
• A defective thermostat (Option D) affects coolant flow, not hose collapse due to vacuum.

To prevent air trapping during coolant replacement:

• Pouring slowly (Option A) reduces but doesn’t eliminate air.
• A coolant exchange machine (Option B) uses vacuum to remove air.
• Opening air bleeder valves (Option C) releases trapped air during filling.
• Thus, both B and C (Option D) are valid methods.

Analyzing thermostat statements:

• Option A: The marked temp is when it starts opening (not fully open).
• Option B: Thermostats rarely cause overheating; failure to open does.
• Option C: The marked temp is when the thermostat starts to open (correct).
• Option D: A and B are incorrect, so D is wrong.

Answer:

C. A defective pressure cap

Question 2