The upper part of the rad on my 90Q has a 3/4 inch long slit ending at the small bolt that fills the rad. It leaks and it looks like ABS material. Question? Has anyone had a similar experience and is it repairable or must I replace the rad? I was thinking like rad sealer OR drill & epoxy or whatever. Thanks John Holt 2 - 1988 Audi 90Qs