The bi-metal strip stops moving at normal engine operating temperature once the temperature at the WUR has equilibrated. If the temperature at the WUR is further increased or decreased the bi-metal strip will move accordingly.
To directly answer your question, I do not know if the bi-metal strip ever unseats itself. I doubt it due to the mechanical function it performs. The bi-metal strip has a range of motion that diminishes at the extremes. That range of motion is compromised with age, one reason why aging WURs go off-spec on their own, usually first seen as a lean cold start and the classic "chugging" at low idle.
RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
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