Barry,
Roam is a 2008 R-25 Classic with a Yanmar 110 HP. It does not have a generator. The sea water pump is gear-driven and on the side of the engine, as opposed to the belt-driven pumps on the front of the other engines. Access is a little awkward, requiring you to lay on top of the engine with your feet inside the cabin and head aft. I place a floor mat over the cabin door threshold for a bit of comfort as John Gray suggested. The space is tight, and it's necessary to reach forward with your right hand and do all of the work one-handed. It's possible to get an upside-down glimpse of the water pump by sticking your head down into the area forward of the muffler, but most of the work is done by feel. I don't use a mirror, but that might help. I believe that plumbing for a generator would make this more difficult.
My first impeller change took about an hour. I've done it about 6 times during Roam's 1500 engine hours. With this experience and the proper tools, I can do the whole job in 20 minutes, unassisted. This does not include the time to dig out and return the tools and parts.
Here's the procedure;
First, I band the new impeller with an electrical tie and let it soak in a cup of soapy water while I remove the old one. I place a plastic tray in the bilge under the pump. I remove the four cover bolts with a ratcheting screwdriver and drop them into the tray along with the flat metal pump cover. I thread the puller into the old impeller and drive the impeller out with a socket wrench. I move the puller to the new impeller and use it to push it in about three-quarters of the way. I slide the electrical tie off, and tap the impeller in gently the rest of the way using the side the socket wrench, then remove the puller. I usually don't change the gasket, but have found the new one can be held in place with a small dab of silicone. I put a 4" piece of Gorilla Tape on the cover and use it to hold the cover to the pump housing while I start the first two bolts, then remove the tape and finish installing and tightening the four bolts. I have extra bolts ready in case I drop one. Dropped bolts eventually find their way to the aft part of the bilge. All that's left to do is start the engine and check for leaks.
I've never yet had a leak, nor have I ever seen any damage to the used impeller blades, but I have on other boats (non- Ranger Tugs) so I consider this to be an important maintenance item.
I'd also like to note that my Yanmar manual says to remove and inspect the impeller every 250 hours. If it's OK, it does not need to be replaced until 1000 hours of service. NO way. Impellers inexpensive relative to the labor required, and I replace them with a fresh part each time. I do keep a couple of old ones as spares.
Rich
