Our 8-hp Evinrude provided six years of dependable service with only minimal maintenance. Except for changing the spark plugs, zinc anode, and lower unit oil every two years, it required no work at all. Until, that is, one day the water pump stopped working. Don’t remind me, I know full well that the water pump impeller should be renewed every two years or so. I had a new complete water pump rebuild kit on board, and tools to do the job, so I lazily figured that I’d just see how far I could go before a new impeller was needed.
Getting to the water pump impeller requires splitting the lower unit at the two or three bolts that join it, and disconnecting the shift rod. A rubber plug covers the access hole for the shift rod. The drive shaft fits into a splined hole in the bottom of the engine crankshaft or powerhead. When the lower unit is unbolted, the drive shaft should slide out of the splined hole in the engine crankshaft and remain with the lower unit — the part with the propeller. Once the lower unit is free of the powerhead, the water pump bolts are accessible, and the impeller is very easily replaced. At least, that’s how it is intended to work. My problem was that the drive shaft was firmly stuck in the powerhead, and due to the design of the water pump, it must be removed from the top end of the drive shaft, not the bottom end. I was able to pull the drive shaft out of the lower unit, but no amount of pulling, beating and screaming would release the drive shaft from the powerhead. I even hung the motor upside down by the drive shaft overnight and dosed it liberally with Liquid Wrench and every other solvent that I had aboard, without success.
What if your outboard motor lower unit refuses to separate? Try inserting successively larger flat-blade screwdrivers into the split, until you can get two large screwdrivers inserted. The screwdrivers will act as wedges to force the upper and lower sections apart. Place a second pair of large screwdrivers on the opposite side of the first two to double the force.
I called the local Evinrude dealer and explained the problem to him. He laughed and advised, “Keep beating on it mate, that’s all we would do and we’d charge you plenty!” This was not going to be an easy fix.
Days later when we arrived at a marina that had an engine shop, I had an idea for a shaft puller. I had the shop cut a piece of 3/8-inch (10 mm) thick mild steel plate about 2.75 inches (70 mm) wide by 8 inches (200 mm) long. One hole of .75-inch (19 mm) diameter was drilled in the center of the plate and two holes of 3/8-inch (10 mm) diameter were drilled about 1.5 inches (38 mm) on either side of the center hole. I inserted two 3/8-inch (10 mm) by 1-inch (25 mm) bolts and nuts into the holes. Next step was to insert the motor drive shaft into the center hole followed by a heavy duty flaring tool tightly clamped around the drive shaft. But, first, the water pump bolts were removed and the pump housing and impeller were moved up along the drive shaft into the cavity of the lower unit to get them out of the way of the shaft puller.
With the steel plate against the motor and the bolt heads against the flaring tool, I carefully and slowly unscrewed the two nuts on the bolts so as to push the flaring tool away from the steel plate. A few small pieces of fine sandpaper (280 grit or so) around the shaft were needed to help the flaring tool secure a firm grip on the shaft. At the point where I was almost ready to admit defeat, the drive shaft pulled free of the powerhead with a tremendous “BANG.” I was still shaking as I collected my shaft puller and the newly freed drive shaft.
Close inspection revealed that the drive shaft had been firmly cemented into the powerhead with carbon residue. Some acetone and a wire brush had it looking like new in no time. The water pump rebuild kit had a tube of special lubricant for the splines on the drive shaft. I had the new water pump installed and the engine back together and running in less than an hour.
Make this simple puller and put it in your spare kit for the awful day when you or a fellow cruiser might need it. Adjust the hole sizes and spacing to suit your individual outboard motor. It’s certainly cheaper than a new engine or a hefty repair shop bill. A final word of advice: change that impeller every two or three years!
—Harry Hungate and his wife Jane live aboard their Corbin 39 Cormorant, and are cruising in the western Mediterranean in 2011.