Porsche IMS Bearing: Why It’s Still a Critical Ownership Issue

The Porsche IMS bearing is one of the most important topics for owners and buyers of water-cooled Porsche models from the late 1990s through the late 2000s. While the issue has been discussed for years, it continues to catch new owners off guard—often because they believe the problem is either rare, already solved, or no longer relevant.

The IMS bearing supports the intermediate shaft that drives the engine’s cam timing. When this bearing fails, the result is frequently catastrophic engine damage. Porsche revised the bearing design multiple times, but none of the factory versions eliminated the underlying risk. As these cars age, the likelihood of failure increases due to time, mileage, and lubricant degradation.

A major source of confusion is the continued use of failure rate statistics from the Eisen class action lawsuit. Those figures were based on data collected many years ago, when the vehicle population was significantly younger. Today’s cars are operating well beyond their original design lifespan, making those numbers increasingly irrelevant.

Another misunderstanding is the belief that an upgraded IMS bearing is permanent. Many replacement bearings still require scheduled replacement. Only pressure-fed plain bearing conversions eliminate the service interval entirely.

For buyers and owners alike, the most important factor is documentation. Knowing whether the IMS bearing has been addressed, how it was addressed, and whether it requires future service is essential to protecting the engine and the investment.