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There are several different locations throughout a vehicle where different components need to mate together, or where two parts may protrude from their enclosures for operational reasons. These areas need to be protected by special seals to ensure that lubricant is contained. The bottom of the engine contains two very important crankshaft seals.



What Is a Crankshaft Seal?

A crankshaft is one of several core components within an internal combustion engine and is the part that connects through a clutch mechanism to the gearbox and transmission systems, to provide drive. It operates at high speed and is driven by the upward and downward movement of the pistons, which are set into motion by explosive compression. As a crankshaft needs to protrude out of not only the rear of the engine (to match up with the clutch and gearbox), but also out of the front of the engine (to provide drive for the ancillaries) it needs another component to provide an effective seal. This is the job of the crankshaft seal.

How Does a Crankshaft Seal Works?

Usually, the Crankshaft Seal is located very close to the engine’s thermostat and the sensor is designed to record the temperature of the coolant by measuring the liquid directly or connecting to the thermostat. On a regular basis, the temperature is sent through to the computer which will decide if it is in the optimal range and if not, alterations are made to other components to help achieve this.

In a worst-case scenario, the computer could switch off the engine, but usually it will send a signal to activate the cooling fan, or may even adjust the fuel to air mixture within the combustion chamber. The computer will then continue to monitor the data provided by the sensor to see if such changes made the necessary difference and if not, to continue with other options. All this action takes place within a very short time span and is part of a constant process and if a fault develops or the computer is not able to adjust operating conditions effectively, it will also activate a warning light on the dashboard to inform the driver.

How Is a Crankshaft Seal Made?

Due to its proximity to high temperatures, the Crankshaft Seal is typically contained within a metal housing. It will be attached to a connector with two wires, one of which provides some low voltage and the other that sends the information back to the computer. Inside the housing is a material that measures resistance caused by temperature changes.

How Does a Crankshaft Seal Fail?

  • Affected by condensation
  • Electrical connections fail
  • Sensor develops a fault

What Are the Symptoms of Failure?

  • Overheating engine
  • Poor engine performance
  • Permanent dashboard warnings or “check engine light” signals

What Are the Consequences of Failure?

  • Engine damage

It is relatively easy to access the seal located on the front of the crankcase, but an entirely different story when it comes to the rear. It’s vital that these seals are carefully replaced as needed.

If you have questions or concerns about Crankshaft Seals or any of your vehicle’s components, come into your local Pep Boys where we can answer any question, help you find any part, or perform any vehicle service you might need.