Many thanks for responses to my problem. I haven't had time to work on/find solution to leak since my last post. Never liked the idea of mating plastic to metal to confine a liquid that is subject to changes in temperature and pressure...bound to fail. The idea of reinforcement with metal at neck sounds like something a good engineer would have thought about in design phase. Eric, I see where you have a different auto, the 1" copper bushing may not fit the 500 SL neck. I have not removed upper hose to measure ID but, did measure OD (1.5") and doubt it will provide necessary fit. I can always try a larger bushing (copper or brass) cut it longitudinally and solder it. Regarding corrosion, the copper can be tinned with lead.