i tried this too, putting the o-ring under the thermostat but when i assembled everything again it wouldn't seal correctly. the housing kept going on an angle when i tightened the screw on the housing. how can i get the housing to seal properly? because i noticed that, even though there was coolant leaking all over the place, i had REALLY good heat that i have never had before in this car when i had that little o-ring in there! if anyone can help me get the housing to not go in on an angle when tightening the screw i would really appreciate it. also, im glad to become part of this cool community of fellow bonneville owners! thanks in advance everyone.

You can try tapping the right side with a screwdriver and a hammer, then tightening the bolt a little, then tapping it again, etc.

I just changed an 89 Delta 88 this weekend. I didn't put the o-ring underneath it, however. Just one on top and then one around the metal pipe. Plenty of blue stuff to seal it up.

hmm what blue stuff are u referring to??

Blue RTV Silicone Sealant. Ask any auto place for some. I put it on the surfaces that mate together.

Blue silicone seal is what I meant by "blue death". See previous post for opinion. Only use to repair damage if replacement part not available.

Please elaborate.