Car crankshaft seal

How to detect the crankshaft oil seal failure

To inspect the part condition on your own, examine the place where the crankshaft comes out of the cylinder block. It must be dry and clean. If there are traces of oil on it, then the crankshaft oil seal has failed. Sometimes also faults in the crankshaft ventilation system can cause oil leakage, so it is advisable to inspect it too.

You may identify that the crankshaft oil seal needs diagnosis by the following symptoms:

• Traces of oil leakage in the engine compartment. In some cases a puddle of lubricant  can also be seen on the ground under a parked vehicle.
• Increased oil consumption.

Causes of the crankshaft oil seal faults

Delayed replacement of oil filter and oil shortens the part service life. This results from the fact that when oil is used for a long time, abrasive particles of dust and dirt accumulate in the place of the seal installation and scratch the crankshaft gasket.

Engine overheating shortens the oil seal useful life as well. When the engine overheats, the  crankshaft temperature becomes higher than that for which the seal is intended. As a result, it warps and loses its ability to ensure tightness.

If the car was out of use for a prolonged time, the oil seal may dry out. If you leave the car in the cold season outdoors, the gasket can freeze up and harden. In both cases, the component will not fit tightly to the crankshaft and will not be able to fulfil its function.

Repair and replacement of the crankshaft oil seal

In the case of failure, the oil seal requires replacement. This is a rather complex procedure, so it is usually performed at a service station. However, if you have appropriate skills, you can replace the seal on your own. For preventive purposes, it is advised to replace the front and rear seals at the same time. Before replacing you have to put the car on a pit and provide its immobility. For replacing the front oil seal, you have to:

1. Dismantle the cover from the timing belt, then demount the belt itself.
2. Disconnect the driving toothed pulley of the crankshaft.
3. Carefully pry up the old oil seal and remove it, clean the mounting spot and install a new part.
4. Reassemble in reverse order.

For the rear seal replacement, you need to:

1. Dismantle the gearbox.
2. Remove the bolts that fasten the flywheel to the engine.
3. Remove the locking plate and the flywheel.
4. Remove the clutch backplate, unscrew fasteners of the rear engine cover on which  the crankshaft oil seal is mounted.
5. Take out the old part, clean the mounting spot and press in a new part in its place.
6. Reassemble in reverse order.

Replacement of crankshaft oil seals involves the necessity to first remove many units and assemblies. If you have little experience in servicing the vehicle, it's best to contact a service station for replacement.