Sounds like an expansion tank and the thermostat should be inside the gooseneck/therm housing, i.e., the usual place.


1953 Chevy 5-window 3100
In the Stovebolt Gallery
More pix on Picturetrail

Dave
Engine & Driveline Moderator

If you can't make seventy by an easy road, don't go. ~~ Mark Twain