coolant restrictor valve ?
 

Well the restrictor valve on that goes from lower hose to heater box broke. just wondering if this is really needed or can i just hook the hose up to the bottom of waterpump? Thanks

Mine has been gone since I have owned my car, but I have put a couple of heater cores in as well.... I've always wondered if the core becomes over-pressurized because of that piece being missing.....