Volvo Repair: water pump by-pass o ring leak, emery cloth, o ring

Question
Hi I have been helping a friend with a 1985 740gle 4cyl
the water pump developed a leak at the o ring between the head and the water pump we have since replaced the water pump and the o ring with oe parts from the Volve dealer it seals for a couple of months then starts leaking again . We have replaced it now 3 times and again it it is leaking..
We are both fairl adept and have done our best to be sure itis alighned straight when reinstalling the water pump. Does this sound like somthing you have heard of before ? Or is it just  us...lol...We really do not know what else to do except try and modify or re- engioneer the o ring sealing set up....Any input will be greatly appreciated...

John

Answer
John, it could be you guys.  Did you clean the portion of the head with emery cloth?  Corrosion and junk in between the seal and the head will not hold properly.  You may also have a really bad corrosion spot and theres nothing you can do about it except have it welded then remachined.  Let me know.  Roger