Keep in mind, the following is just my opinion. 

Problems with seal leaks on the water pump end of 532 and 582 have persisted for years. I used to consider this problem "one of life's mysteries". Rotax made a number of changes in components dating back to 532 production. Some of these helped, but there was never a definitive cure. Coolant would leak past the outer seal, and if the weep hole between the two seals was open, would escape to the outside where the problem could be witnessed by the pilot upon preflight. That is why you may hear discussion about the "witness" hole in dialog about this topic. If the witness hole is blocked, (as it has been for many years accept for the 618 and latest version 582) the coolant could eventually leak past the inside seal, contaminating the lubricating oil of the Rotary Valve drive. I am not convinced there was ever a failure in this area that could not have been prevented by even a nonchalant preflight. The failure mode is slow, but progressive. Unfortunately, coolant is not a sufficient lubricant for the Brass worm gear on the RV shaft. As the concentration of coolant increases in the RV oil bath, effective lubrication decreases. It all stops when the teeth on that brass gear are gone. The engine just stops running without major damage to its internal components. The engine repair is usually limited to a brass gear, gasket set, and labor. 

Cause

For me, the mystery has been: "How can the Teflon lips on the seals so quickly wear that hardened shaft?

I received some information from a good friend and customer up in Cincinnati Oh. He had been having repeated problems in this area and had stumbled across an article in a technical publication which described similar problems with one major heavy equipment manufacturer, and also one popular Japanese motor cycle manufacturer. If I may paraphrase, each of the companies had determined the use of silicate in antifreeze formulation is "The Culprit" . The rationalization in my mind is that the silicate, a component of low cost "aluminum compatible" antifreeze is a hard particulate which effectively "wet blasts" corrosive deposits from cooling systems. A negative side effect is when this particulate piles up on the mating surfaces between a Teflon seal and a hardened shaft, the relationship is like a cutting tool and a lathe. 

Solution

This is just too simple. It seems, the motorcycle manufacturer discovered that the leak problem didn't occur if Honda Brand coolant was used. You may ask, is there anything special about that coolant? I don't really know, but the something special that isn't there is "silicate". This explanation made sense to me, and we began sharing the information with customers. We are now looking at about 3 years of personal experience and input from customers. I am not aware of a single instance of this phenomenon occurring where the coolant in use was "silicate free" 

Availability of silicate free coolant

Presently, most auto parts stores offer coolant with those magic words on the label "contains no silicate". Havoline brand offers it, but make sure it is the silicate free formula because they also have the other. Down here in Florida, it isn't even much more expensive than the regular variety. Up in Ohio, it was about 3 times the price.

I can't describe how frustrating this problem has been for some of our customers and even worse for those of us on the supply side of service. In my mind, Rotax is to be commended for their numerous improvements in attempting to find a remedy. The new generation 582 has a redesigned crankcase that accommodates a rotary seal just like that of the 618. So with some reengineering Rotax solved a problem (which had nothing to do with design deficiencies) the hard way.