SD40 unususal Seal issues?

[Soulflyer1980]

Good Morning Guys,

I haven't contributed to the flow of valuable expertise for a while now but now an issue baffles me and I can't seem to wrap my head around. Maybe I'll find an answer here.

A while ago I changed the oil in the SB saildrive using a sucking pump and this nipple to attach it to the SD https://www.frenchmarine.com/product...ldrives-2355-3
I connected this nipple to the lowest hole on the SD and had both Bolts removed from the Top Lid of the SD so air can go in while I suck out the oil. The job went very well and after I filled up the right amount, I was satisfied. After a week or two, of repeatedly checking the SD oil before using, I noticed the color and viscosity changing of the oil. BUSTED outer Seal is the diagnosis, which seems to happen OK.

But after the same procedure about a month later (I change the Fluids at different times but same intervals) on the Port SD and similar time later I had water leaking into that SD as well

Now my question is, does sucking out the oil damage the outer seal of the SD? The oil is quiet thick so maybe while sucking it out it creates a 'vacuum' inside the lower part of SD and the outer Seal gets 'sucked' inwards?

It is less about the water intrusion or seal itself, I just don't want to keep going with that oil change method and having to change the seals everytime too


Thanks a lot for any input

P.S. anybody ever changed both SD seals under water so far?

Ferdinand