[Walt Fricke]

Dave - when the oil thermostat fails, it has zero value. It is filled with some kind of wax which expands and contracts with heat, and cannot be rebuilt or repaired when it fails. Of course, if you get the old part back, you can test it - you put it in the freezer for a while, and then toss it into a pan of boiling water. If the tiny, sort of wide head nail part emerges in the water, then it is good and you were taken. But offs are the shop knows how to test these and it is bad.

I once tried to refurbish the Bosch motor which on my car is back on the engine for the heater. It is not made to be taken apart, though you can do it. The bearings are not made to be replaced, though I was able to do some disassembly, cleaning, and reassembly with some grease here and suitable oil there. This worked for maybe a month. I don't think you can purchase bearings for these - google Bosch 12 volt motors and replacement bearings and Porsche and see if you get anything.

In the 70s and 80s Porsche seemed to use rather low end - despite being Bosch - electric motors. Though the virtue of low end was not super expensive - back then - to replace.

There is no market worth considering for these failed parts. I'm not trying to excuse what this shop did by not giving you back the junk (well, presumably junk) they replaced. But this sounds like the classic quiz question for first year Contracts in law school - there was a breach of contract, but if there was no value one could attach, what is the remedy. Michigan resolved this, it appears, by assigning a sort of penalty value of some kind.

The working insert is $130 from Pelican. The whole external thermostat assembly is a bit over $500. A reasonable question is why not replace just the insert. Though shop economics sometimes says you are ahead if they just replace an assembly, saving the labor of disassembling and reassembling along the way.