Hurth ZF 25M

A while back when putting the engine back into the engine room I misread the oil dipstick markings and overfilled Hurth transmission with ATF oil – it instantly overheated while the engine was getting “broken in” at the dock after the rebuild. Noticing the excess temperature the oil level I got out the manual and read it only to find out that indeed overfilling will cause this type of transmission to overheat. Adjusting the level lowered the temperature to operating level and transmission seemed to work fine. Hidden inside, however, shaft seal broke apart causing shaft to wobble and loosen the bolts that held the seal together. About 50 hours later this becomes evident in the light of what seems like a complete engine failure, and of course, far out at sea. Luckily Hurth makes lots of these and TAD will gladly ship one to you at which point it becomes a relatively easy swap out job. I had to get a new damper plate and a keyhole adapter plate, TAD has these in stock as well. Bottom line is read the ZF manual and don’t count on the overheated transmission: something will fail sooner or later - knowing all this back then I would have just gotten a new one right then and there.