hose plastic part issue
you have to be carefull with thoose plastic connectors (where the big hose wil be attached) sometimes ckacked on the lower part. between when hose finish and base starts. internally you will see e little crack. maybe cause by the hose vibration. so you will start to see a leakage at the top of the thermostat assy, but is not easy to know from where is. This happen to me when i replace the hose clamp an the hose later and the problems contunue there. i remove the cap and inspect inside finding a little crack inside the hose connector. I buy a new one and the vendor sent me a used one by error, when i inspect it had the same condition....so be carefull...