Porsche: Magnesium Fan Housing Failure

Magnesium. A wonderful metal for parts where weight savings are sought. Unfortunately, over time magnesium parts fail from existence.

CASE STUDY

Our example fan housing and partner fan for this study are out of a 1980 Porsche 911 SC Targa with an '85 3.2 liter engine.

Genuinely coming unglued, this housing remains functional (albeit now dragging its partner fan down with it) thanks in large part to its surrounding retaining strap. Because there's no guarantee of this housing remaining together for seconds or years, a housing run in this condition is risky. Consider what occurs when a housing collapses at high rpm---messy is an understatement.

Once structurally weakened, fan housings tend to go out-of-round given the pull applied by the fan belt.

When a housing has been pulled out-of-round enough, its partner fan will begin making contact with it.