NS70C Nissan 1999 - Crack in Gearcase where Prop Shaft Housing meets

[ShawnQ]

I've got about a 1" crack in the gearcase on the port side, right where the end of the prop shaft housing sits out of the lower unit.

It does not appear to be leaking, my lower unit fluid does not have water in it (although the oil is dark, it isn't milky and still smells like gear oil).

I only paid a few grand for the boat/motor/trailer, and don't want to drop a lot of money into the engine. I was about to pull the lower unit to do an impeller, and flush/descale the cooling passages with Rydlyme, when I saw the crack.

Should I drill a hole to stop the crack, and have it welded? Use epoxy/JB weld? How about one of those cold alum. welding rods?

The boat is used within a few miles of home, so I don't run a long ways or anything. If I end up stranded, I wont be offshore or anywhere in a huge distress (unless I end up in a channel, in which I can use my electric to get to the shore).

Any input is appreciated. I can get pics if needed.

Thanks,
Shawn

 

[pvanv]

Re: NS70C Nissan 1999 - Crack in Gearcase where Prop Shaft Housing meets

Shawn,

the o-ring seal for the prop shaft housing is way forward of that, so a minor crack won't violate the lube area. The crack is likely caused by salt crystals growing and expanding (or possibly water freezing) in there. The "Factory" way to fix this is with a new LU housing. That said, you may well have some success by taking it to an experienced aluminum welding/fab shop. Yes, they will probably drill a stress relief hole, and then weld the crack. Likewise, a good clean bond with JB weld or similar metalized epoxy may (or may not) be successful. prevention, by adequate flushing will help to avoid that.

 

[dtj]

Re: NS70C Nissan 1999 - Crack in Gearcase where Prop Shaft Housing meets

Easy, have that thing MIG welded by any competent shop and you should be good to go for very little money.