Originally Posted by
David T
As Dave S mentions, the heater valve does not have a high failure rate. The fact it failed quickly and multiple times would suggest something wrong in your technique installing it. I have never seen one break, they either get stuck and won't move and/or leak. It may be possible if you overheat the motor you could "cook" the valve and make it more prone to breakage. It isn't an expensive part, just difficult to access and a little messy because of the coolant.
David Teitelbaum