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Question

Difficulty: MediumCooling System

While performing an inspection on a vehicle's cooling system, a mechanic discovers a steady drip of coolant coming from the weep hole on the water pump housing. What does this symptom indicate?

  1. A
    The thermostat is stuck closed and venting excess cooling system pressure
  2. B
    The alternator has overloaded the drive belt system and cracked the housing
  3. The internal mechanical shaft seal of the water pump has failedAnswer
  4. D
    The engine is burning an overly lean fuel mixture that cracks the pump casing

Answer

The internal mechanical shaft seal of the water pump has failed.
The water pump features an internal mechanical seal to keep coolant from reaching the shaft bearing. When this seal wears out, coolant leaks into a cavity and drains through the weep hole on the underside of the housing, providing a visible sign that the pump must be replaced before catastrophic bearing seizure occurs.

Step-by-Step Solution

1
Identify the purpose and location of a water pump weep hole.
The weep hole is an engineered passage located between the internal coolant seal and the drive shaft bearings.
It vents leaking coolant to the outside to prevent fluid from washing away bearing grease.
2
Analyze the observed symptom of coolant dripping from the weep hole.
Coolant passing through the weep hole confirms that the primary shaft seal has deteriorated.
A worn seal allows pressurized coolant to bypass the impeller cavity, necessitating replacement of the water pump assembly.

Key Concept

Water pump mechanical seal failure diagnosis
Estimated Time:1m 0s
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Topics

Cooling System

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