Flakey drains.
Guys, I had a similar experience when replacing the center, aft of three cockpit drains in our E31. The dang tube was a common, thin walled brass sink or basin drain such as you'd find in the home plumbing section of your local hardware store that had been glassed in at the factory, grrrr! Furthermore, it was on the verge of being eaten completely through which would have resulted in the 1 1/2" hose separating from the scupper and possibly sinking the boat. The fix was to install a proper Perko scupper with check ball such as this one currently being offered on eBay: 141605547953 I bought three of them used at Minney's not too far from home and as I recall, paid $15 or so each one of them. Then, and this is for you Loren, had to strip all the chrome off them before installation. It's all good now. It might be worth some of you, especially E31 owners to check that aft drain, it might be in the same shape as mine was and a tragedy about to occur. Glyn Judson, E31 hull #55, Marina del Rey CA