The problem wouldn't be remaining closed, it would be remaining open. The temp-sensitive valve in the Mocal plate doesn't ever restrict the flow to the cooler.
Basically the Mocal has two paths for your oil to flow through, one through the cooler, and the other a direct bypass that doesn't go through the cooler. The passageway to the cooler is permanently open and doesn't have a valve. When the oil's cold, both passageways are open, and some oil flows through the cooler, but most of it bypasses (path of least resistance).
The thermostatic valve begins closing off the bypass route at around 170-175-ish, eventually closing completely and forcing all oil through the cooler somewhere around 185-190-ish.
You could probably test all of this by taking the Mocal plate off the car, placing it in an pot of water, and heating it up while watching with a thermometer. See if the valve operates and blocks off the bypass at roughly the correct temperature or not.
|