We here we go. I have a 1940 Olds Series 90 Touring with a 257 straight 8. Had the tipical dripping after running. Getting ready to sell this beauty. wanted to trouble shoot the issue. Took the hoses off and emptied the rad. Looks good so far. very clean. Took the thermostat housing off the head. Guess what not thermostat. Well, here is where the problem begins. Was on the OCA fb page and troubleshot with guys there. I was missing the thernmostat and the retainer? well ordered all that and it came yesterday. Well was going to get it installed. Ya right. The thermostat fits in the thermostat neck great. The retainer does not. The thermostat does not stay in the housing. Seems the housing is not totally round per the design. The retainer I was told to buy was round. doesn't fit. Help me......I cannot find any information in manuals NOTHING to tell me what I need. I will try to get pictures on the post...... Thanks Tom

 

It appears that there were two different types of thermo housings in this era.
They use different retainers.
With the car being over 80 years old, there's no guarantee that that is still the original engine.