i didnt have an o ring for the thermostat would that cause it to leak like that ?

my 1992 e36 325i has a 99 m3 3.2L I6 swap in it and last night it got hot on me well come to find out the small plug beside the radiator cap had blown out....replaced it and had no heat so i replaced the thermostat in which i used a good small bead of red rtv on the housing to seal it good and now have a leak from underneath looks like its come from water pump and the belts screech from water on them. i didnt have an o ring for the thermostat would that cause it to leak like that ? please help if someone can.....and also how hard is it to do a toyota supra 2jzgte swap into an e36 i found a kit that comes with a plug and play harness and custom mounts for motor and trans and custom drive shaft any and all comments and help is appriciated. shoot me an email at BRETTWIL13@GMAIL.COM THANKS GUYS

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[Nick at Pelican Parts]

Yes the o-ring could cause the leak. The overheating might because of the bad head gasket that caused excessive pressure in the cooling system and blew out the bleed plug but that is pretty rare

- Nick