Oil Temperature Control Valve Thermostatic Element Failure

[Jagdpanzer]

Went out for a drive recently and after about 30 minutes took the opportunity to scroll through the digital readouts for coolant, oil, and voltage. Coolant temp and voltage were normal however, much to my surprise found the oil temp at 240 degrees F. Normally it runs within a few degrees of the coolant temperature under street driving conditions with usual summer time ambients.
Following is an account of the steps I took for investigating and correcting the high oil temperature problem:

I replaced the oil cooler with a NOS cooler when I installed the 427 engine which had been working fine so I suspected there was something not quite right with the oil temperature regulator valve assembly.
To pull the regulator valve assembly apart from the filter housing I used a good pair of right angle internal snap ring pliers. Following photos were taking using my spare engine which was easier to photograph.
Attachment 15394
Attachment 15395
The plug released after a few taps from a soft blow hammer and wooden dowel.
Attachment 1
Before starting the investigation I left engine set for a few days to allow the oil to drain back to the sump. Had very little oil to deal with when the the retainer cap popped free.
Attachment 15396
The thermostat element that provides the force for controlling the temperature regulating valve sits right behind the access plug.
Attachment 15397
The thermostat element, regulating slide valve, and return spring are easily removed.
Attachment 15398

To be continued