First of all tell your friend to join this forum. This issue has come up here several times and its happened to me twice. I recall it was directly happening because I like many others were using a cheap after market core. I went back to a factory heater core and have not had any more problems. Thats been over 12 years now. Cavitation wont cause the heater cores to fail. Now we do have an orface in the feed line nipple fitting thats threaded into the passenger side head. Don't worry about buying another fitting. They are no longer sold by anyone. I found this out when I rebuilt my engine in 2006 and had Ford do a nationwide search. They found one about 7 miles from my home and I bought it. No reason for getting it at the time and I still wonder why I got it. Another item thats impossible to buy because Ford is out of stock and will not be replacing them is the valley pan nut drain hold down piece. Thats the 3/8 square drive nut that holds down the rear of the valley pan and acts as a drain too. I bought 11% of the remaining stock and then posted the information here. They sold out in less than 1 day. I did this because I felt I could help out a member that lost their drain / plug but so far nobody has needed one yet. Spare parts are good parts to have when you can't find what you need. Thats why I have 3 complete sets of 3/8 and 1/2 inch drive sockets and combo wrenches from 7/16 to 7/8 inch....
