I’ve been on winter break. . . which ended today! Back on the boat for a couple of hours this afternoon as it sits in the boat yard, I spent some time crouched over the engine disconnecting the engine/shaft coupling. Why? Because of something I should have done 2 years ago when I had it all apart. I knew at that point that the shaft was pitted and worn in several places, like where it spins at the packing nut and cutlass bearing. Why didn’t I get a new shaft made at that point? Can’t really answer that question, except to say that I was just muddle-headed. It would have saved me a fair amount of work this year decoupling the shaft.
If you’re reading this post, it is more than likely that you’ve done this, or had it done. If not, let me briefly explain. The engine and shaft are joined at the back of the transmission with a two-piece fitting. The fitting is two flat discs, one attached to the engine side, and one attached to the shaft. The disk is pressed onto the shaft and locked in place with a “key.” The key is a piece of brass, bronze, or even steel that has a rectangular cross-section and is several inches long. The key is installed into the shaft in a machined slot, called a keyway, which matches a keyway that is cut into the disk. Without the key in place, the shaft would spin inside the disc. The engine and shaft discs are joined together with four bolts passing through, oriented fore and aft.
Two years ago when I removed the engine to repair the engine bed, I removed the prop and slid the shaft out forward, because I was unable to separate the shaft from the coupling. I captured the shaft in my vise of the workbench, and removed the coupling with a wheel puller – with a great deal of effort. When I put it back together, I assembled the shaft and coupling with waterproof grease, hoping that this would make subsequent separations not only possible, but easier to boot.
The bolts removed reasonably easily (I greased them too), but I haven’t gotten as far as pushing the shaft out of its disc yet. Although my access to this part of the boat is much improved since I enlarged the access opening, it’s still awkward. To work on this, I lean over the engine and rest my abdomen on top of it, then work as long as I can stand it, which is about 5 minutes at a time. So my progress today was removing the four attaching bolts, and beginning to replace them with four longer bolts. With the longer bolts in place of the originals, I can place a spacer between the discs centered on the end of the shaft, then draw the discs together again with the bolts. This (hopefully) will push the shaft out of its disc. But it takes time, and all of that time is spent with most of my weight pushing my abdomen into the top of the engine.
So after a couple of hours I was ready for a break. No sense in turning this into misery! Probably one more day’s work will tell me if the shaft is going to separate from the disc this way. If it doesn’t, I’ll pull the engine again – it’s not too hard, nor too time consuming.