Car crankshaft pulley

How to detect the crankshaft pulley failure

The crankshaft pulley examination is advised to be performed every 60,000 kilometers. Cracking or warping of the elastic element, splitting of rubber and metal parts, cracks on the hub or near the fastening holes, multicolored stains on the outer housing surface indicate that the part needs replacement.

The absence of visible faults cannot always guarantee that the part is in good order. To check if it is working, you must mark the pulley from center to edge, then start the engine and switch on various equipment to provide maximum load on the belt drive. Then you should shut down the engine and see if the marks match.

You may identify that the crankshaft pulley has to be examined, by the following symptoms:

• the drive belt has been destructed prematurely;
• vibrations are felt in the passenger compartment;
• while the engine is running, there are abnormal sounds from under the hood: noise, knocking or whistling;
• the alternator relay or fuse often blows out.

Causes of the crankshaft pulley failures

The crankshaft pulley has a limited service life and belongs to components that are subject to preventive replacement. The part’s average life is 90,000-120,000 km.

Premature wear of the pulley can be caused by aggressive environmental impact. Temperature drops, ingress of technical fluids including petrol and oil, lead to the breakdown of the dampening element and the sleeve bearing.

The car operating conditions significantly affect the part life. City driving, often at reduced rpms, sharp starts and braking create high loads on the unit.

Installation mistakes are a quite common cause of the pulley failure. Usage of inappropriate equipment or old bolts, excessive or insufficient tightening torque of fasteners, intensive shock loads may result in the part’s cracking. After installation you have to check the alignment of the drive elements; in addition, the drive belt replacement is advisable, otherwise the risk of the pulley premature wear will substantially increase.

Sometimes belt pulley failures are directly associated with the installation of extra equipment not envisaged by the car manufacturer, like an air conditioner or another alternator.

Replacement of the crankshaft pulley

If any failures occur, the pulley needs replacement. Installing a new part independently is not difficult, but special tools are required: a handle to hold the pulley, a drive handle, a puller and a deep socket. Steps should be carried out in the following order:

1. Mount the car on the lift.
2. Dismantle the front wheels.
3. Remove the engine cover, the alternator belt, and the air filter.
4. While holding the pulley with the proper tools, unscrew the bolt. For this a  proper diameter wrench and a pry bar are used.
5. Remove the part with a puller.
6. Clean the mounting seat from dirt, lubricate the parts.
7. Install a new spare part in the reverse order. It is necessary to tighten the fastening bolt with the torque specified in the car technical documentation