Automotive Cooling System Quiz

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Questions and Answers

What temperature range does the cooling system aim to maintain for the coolant?

70°C to 75°C

85°C to 90°C

60°C to 80°C

79°C to 85°C (correct)

What happens when the coolant temperature exceeds 97°C?

The cooling fans are deactivated.

The computer displays the message HOT ENGINE-THROTTLE 6 LIMIT. (correct)

The engine speed will be increased to high RPM.

The engine will automatically shut down.

At what temperature does the engine speed increase due to low water temperature?

Below 52°C

Below 40°C

Below 50°C

Below 46°C (correct)

What color indicates a HOT status on the temperature gauge?

Red Signup and view all the answers

Which component is responsible for limiting engine loading during high temperature conditions?

The control computer Signup and view all the answers

How does pressurizing the cooling system benefit engine operation?

Raises the boiling point of the coolant Signup and view all the answers

What initiates the sequential energizing of the cooling fans?

Coolant temperature increase Signup and view all the answers

What will happen when the engine coolant temperature drops after being overheated?

Engine speed will return to idle. Signup and view all the answers

What action is taken when the engine temperature is detected above 101°C for 5 minutes?

Engine comes to idle. Signup and view all the answers

What is indicated by the color coding on the temperature gauge?

Temperature conditions of coolant Signup and view all the answers

What pressure does the pressure cap open at to relieve excessive pressure in the cooling system?

20 PSI Signup and view all the answers

What happens when the low water level switch opens while the engine is running?

The crew message 'LOW ENGINE WATER LEVEL DETECTED' will display. Signup and view all the answers

Which of the following substances must a coolant for EMD engines effectively prevent from forming?

Scale or sludge deposits Signup and view all the answers

What is the primary type of corrosion inhibitor used for EMD engines?

Borate – nitrate type Signup and view all the answers

What is NOT a requirement for a coolant to be suitable for use in EMD engines?

Catalyze chemical reactions Signup and view all the answers

What should coolant samples be analyzed for?

Corrosion inhibitor concentration Signup and view all the answers

What concentration of borate – nitrate should be maintained in the cooling system?

5625 parts per million Signup and view all the answers

What will occur if the low water level condition is detected while the engine is shut down?

A crew message will be displayed. Signup and view all the answers

Where is the operating water level instruction plate located?

Next to the water level sight glass Signup and view all the answers

What is the primary function of the engine mounted water pumps?

To draw and pump cooling water into the engine Signup and view all the answers

What does the vacuum breaker in the pressure cap help to minimize?

Damage from pulling a vacuum on the system Signup and view all the answers

What happens if the EM2000 computer detects a failure in both temperature probes?

The engine speed defaults to idle, and the cooling fans remain in their last operational status Signup and view all the answers

Where are the electronic temperature sensing probes located?

In the water line from the oil cooler to the water pump Signup and view all the answers

What provides cooling for the air compressor?

Part of the water from the engine pumps without any valves Signup and view all the answers

What is the role of the radiator banks in the cooling system?

To dissipate heat from the coolant Signup and view all the answers

What controls the operation of the cooling fans?

The EM2000 computer through contractors Signup and view all the answers

What does the bypass line between the inlet and outlet lines do?

Reduces the velocity in the radiator tubes Signup and view all the answers

What stored message indicates a single temperature probe failure detected by the EM2000?

ENGINE TEMPERATURE FEEDBACK FAILURE Signup and view all the answers

Where are the radiator assemblies located on the locomotive?

In a hatch at the top of the long hood end Signup and view all the answers

What happens when both temperature probes fail?

The system ignores the failed signals and behaves as described Signup and view all the answers

Study Notes

Water Cooling System of GM Locomotive

The engine mounted water pumps draw cooling water from the expansion tank and lube oil cooler assembly, and pump it into the engine.
Heated water leaves the engine and flows through two radiator assemblies where it is cooled.
Cooled water returns through the oil cooler to repeat the closed loop cycle.
Part of the water from the water pumps is piped to the air compressor.
There are no valves in this line; air compressor cooling is provided whenever the engine is running.

Flow Diagram of Water Cooling System

Components include radiators, expansion tank, lube oil cooler, Water Pumps, compressor, ETP-1 & ETP-2, Engine crank case and EPD.
Flow is clearly shown in diagrams.

Electronic Temperature Sensing Probes

Two electronic temperature sensing probes (ETP-1 & -2) are located in the water line from the oil cooler to the inlet of the water pump on the engine's left side, near the water temperature gauge.

Engine Temperature Feedback Failure

If the EM2000 computer detects a failed temperature probe, it sends a message "ENGINE TEMPERATURE FEEDBACK FAILURE" to the display screen and stores the message in archive memory.
If both probes fail, the computer ignores the probe signals, keeps fans in the last operating status, sets engine speed to idle, and stores "NOT LOADING ENGINE TEMPERATURE FEEDBACK FAILURE" in archive memory.

Radiators and Cooling Fans

During circulation through the diesel engine, air compressor and oil cooler, the coolant picks up heat needing dissipation.
Water temperature is regulated by radiator banks and AC motor-driven cooling fans.
Radiators are located in a hatch at the top of the locomotive's long hood end.
Each radiator bank consists of two quad-length radiator core assemblies, bolted end-to-end.
Headers are mounted on the radiator core forming the inlet and outlet ends of the radiator assembly.
A bypass line is provided between the inlet and outlet lines to reduce velocity in the radiator tubes.
Cooling water from the engine is piped to the headers of each radiator bank.
Discharge from radiators enters the oil cooler; water returns to the water pumps for recirculation.
Eight-blade, 52-inch cooling fans are controlled by the computer, which acts on the contractors.
The computer controls fan sequencing duty cycle and speed (low & high) to ensure even fan and contractor wear.
The two-speed cooling fan system consists of two full-speed contractors (FCFA & FCFB) and one slow-speed contractor (FCS) per cooling fan motor.
The system maintains coolant temperature within a predetermined range of 79°C to 85°C.
Fans are driven by a two-speed AC motor powered by the companion alternator.
Fans are energized in sequence based on coolant temperature; coolant temperature drops cause fan switch-off.

Speed due to Cold Engine during Engine Idle Conditions

If ETP-1 & -2 detect the temperature is below 46°C engine speed increases to TH-2.
Engine remains at TH-2 until temperature stays below 52°C.
Once temperature surpasses 52°C speed drops back to idle.
Isolation switch must be in RUN position for speed increase (reason displayed as "ENGINE SPEED INCREASE – low water temperature").

Hot Engine Condition

Engine cooling water temperature is sensed at the water pump inlet.
Excessively high temperatures trigger "HOT ENGINE-THROTTLE 6 LIMIT" message (temp. 97°C).
Engine loading is limited in throttle positions 7 or 8.
Condition persists until temperature returns to a safe limit.
Temperature of 101°C for 5 minutes causes the engine to idle.

Temperature Gauge

A temperature gauge is located on the inlet line to the water pump.
Gauge is colour-coded: cold (blue), normal (green), hot (red).

Cooling System Pressurization

Cooling system is pressurized to raise coolant boiling point.
Higher engine operating temps possible with minimal coolant loss due to boiling.
Pressurization ensures uniform water flow and minimizes possibility of water pump cavitation during transient temperature conditions.
Pressure cap on water tank filler pipe opens at 20 PSI, relieving excessive pressure and preventing damage to components.
Vacuum breaker on cap minimizes system damage during cooling.

Operating Water Level

An operating water level instruction plate is provided.
Indicates LOW (minimum) and FULL (maximum) water levels for running or dead engines.
Water level should not fall below LOW mark.

Water Level Switch

A water level switch (float type) is installed in the cooling system water tank, connected to DIO1 input channel 7 (labeled NO LWL).
If low water level switch opens for 10 seconds while engine is running, a "LOW ENGINE WATER LEVEL DETECTED" message appears, along with a 60-second alarm.
Fault is archived if low water level is detected while engine is shut down. Engine is not allowed to start. "ENGINE WATER LEVEL DETECTED" displayed for 60 seconds.

Coolant

Coolant circulates through the engine to transfer heat from engine components to the radiators.
Engine coolant consists of water, corrosion inhibitor and, where appropriate, antifreeze.
Coolant samples should be taken and analyzed regularly to maintain proper corrosion inhibitor solution.

Coolant Requirements for EMD Engines

Suitable coolant must adequately transfer heat, not form deposits, prevent corrosion, and not deteriorate cooling system seals or gaskets.

Corrosion Inhibitor

The main corrosion inhibitor for EMD engines is the borate-nitrate type, available in powder and liquid form.
Powder/pellet inhibitors should be dissolved in water before adding to the cooling system.
Borate-nitrate level must be maintained above 5625 parts per million.

Water Pump

Water pumps are impeller pumps.
As the impeller rotates, curved blades draw coolant from the radiator bottom and force it to the water jacket.
Two engine cooling water pumps (on 8-cylinder engines) are self-draining centrifugal pumps rotating opposite the crankshaft.
Pump drive shaft is supported by two permanently sealed grease-lubricated ball bearings requiring no maintenance.

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Description

Test your knowledge on automotive cooling systems with this quiz. Questions cover temperature management, gauge indicators, and the functionality of cooling system components. Understand the critical aspects of maintaining optimal engine temperatures.