External Oil Thermostat

[Roadrunner911]

Recently had my '82 911 SC up on a lift with the engine at operating temperature and noticed the lines to my front fender oil cooler were not even warm. I suspect my external thermostat is not operating. Pelican search revealed several related entries on this subject but nothing on replacing or repairing the thermostat. Anyone have experience with this? I noticed thermostat rebuild kits and replacement units are available. Also, that there is a problem with stripping the threads when removing the thermo. I appreciate any advice or anyone's experience with this. Replacement thermos are nearly $400. By the way, the car does not run particularly hot, gauge slightly above middle position on warm days.
Thanks,

[fintstone]

oil thermostat (wheel well) failure

[jaydubya]

It won't open until around 180degF. That's right around the first white line after the lowest one on the stock oil temp gauge (uh, I guess the second white line). Better if you can test with a thermister or temp probe on the inlet oil line to the thermostat (it's the warm one ). Like that other thread says, it's not really common for them to fail but it does happen. Even after it opens it will take a few minutes for the outsides of the lines to the front of the car to heat up to the touch.

[Bill Verburg]

A 911 idling at low ambients will not open the front t stat for a very long time. I would hold off on a diagnosis of fault untill you can run it hard w/ at least 65&deg weather

[Roadrunner911]

Pelicanites come through again. Thanks for the info guys. As previously mentioned, when I originally discovered the problem, the car was very warm (hot) after a 40 mile drive. So, I suspect the thermostat is not operating properly since the oil lines to the cooler were cool. Looks like the best option is to replace side piston as fintstone mentioned in the linked thread. I'll see if I can do it on the car to avoid the thread issue hopefully.