Pattern Failure: Crankshaft Pulley

The term "pattern failure" literally means a failure along a pattern, i.e. a similar and repeatable failure both in time and nature. Many of the typical auto parts failures discussed in my car-care articles are of a design-specific nature. That is, certain part designs tend to fail along a pattern, irrespective of vehicle make and model.

Pattern Failure Explained
All air filters, regardless of vehicle make and model will eventually get clogged with dirt and need replacement at more or less specific intervals. All vulcanized rubber engine mounts will eventually compress to the point of failure, due to the constant forces being exerted on them. Again, at more or less a similar approximate time.


What I'm attempting to do with this series is to show parts pattern failures that I'm personally familiar with and seem to follow along make and model-specific lines. This approach is solely for your own information, and is not intended as a critique of any particular auto manufacturer.


In this installment, we'll focus the frequent failure of crankshaft pulleys—also known as the crankshaft vibration damper—on mid- '90s, Ford-built, four-cylinder engines, such as the older 1.9-liter found in the Escort model. I have also seen similar failures on other Ford engines but, interestingly enough, seldom on the company's V-8 designs.

Two-Piece Pulley
Many manufacturers use a crankshaft pulley with a two-piece design, consisting of the central "hub," an outer "drive ring," and a high-density rubber composite "absorption layer" sandwiched in between. Variations of this design have been in use for decades with great reliability. It's not uncommon to see original equipment pulleys still in service on '60s-era vehicles.