Could be just a simple pressure leak. Do you have the proper cap?
Are you finding this after the engine has sit for a period of time, like overnight? I have seen this many times, the system cools down and a small leak will occur at the hose connection on the 'stat housing. Need to clean the inside of the hose and the outlet pipe, put some silicone grease on the connection and it may help.
I pulled the chrome thermostat housing the other day to look at it and its O ring seemed fine and it had no corrosion.Theres also no coolant around housing either. I also put a 180 thermostat in it. It had a 195 in it and was running hotter than i would have liked.Before I went to the car show last night I torqued the intake bolts down and I did not notice any coolant today. It has only done it twice this week so Im still not sure if its fixed.
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