I'm sure there are those out there who have had this problem and the only way to correct it was to have it replaced by the local shop or dealer.

I'm talking about the thermostat housing splitting at the manufacturing's molding seam across the top as seen in the picture below--pointed out at the tip of the screwdriver.

I found myself in the situation while away from my shop and I didn't want to leave the car. So looking around for a solution I came upon one of those stainless steel screw clamps, just the right size. I opened it up so I could work it around the tube like housing then screwed it tight--thus forcing the seal closed. The housing was hot because I let the engine idle while doing this so I could see if it was going to work. As you can see in the 437 photo, it still leaked, but the leak you see is after a 50 mile drive.
If you have this problem, give this a try. It works. Just to be safe, I've since replaced the whole housing with new, but I'm keeping the clamp in the car.

Cheers

 

Good ingenuity. One thing I have done when replacing those plastic housings is to put some silicone sealer on the end caps. They all seem to leak there. I find it a little hard to believe that someone hasn't produced those in aluminum yet.