Your exactly right Doc, the cores that have the same size inlet and outlet do not have the valve.docvette said:Doc hereimp:
Try the top Hose to the water pump, If I remember that far back, I don't think it made any difference which way the flow went, (The Core Dosen't Care)
On the later Cores, The inlet had a Valve for water Flow shut off, where yours is old enough I think just mechanically Shuts a heater door on the Heater box. These usually are 5/8 and 3/4 hoses types , so you can't reverse them.
Hope it helps!