Quote:
Originally Posted by nicklockard
ALL thermostats are a weak point. It's the technology: modern T-stats are designed around a wax phase-change pellet and have 2-stage behavior. The wax pellets become degraded over time (about 8-12 seasons, depending on how bad the seasonal swings are) and they fail to COLD because the wax pellets allow stage one early opening to occur earlier.
It's just a technological limitation. I'd wager that 75% of cars on the road today have t-stats running colder than designed temperature specifications. Nearly every used car I've ever put my OBD scanner to ran colder than spec.
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I was referring more to the plastic tabs that hold the thermostat in the housing, than to the materials that make up the thermostat. Those tabs seem to break all the time. Compare that to the thermostat design on earlier BMWs (e30, e34, e46, etc) where the thermostat is the same part but not clipped in to the housing. Those rarely, if ever, failed, because the thermostat material itself is rarely the cause of the failure.