Re: 1985 Merc 115 hp outboard impeller replacement
Quinton,<br /><br />Not too hard. Tips? Just keep your eyes open. Most problems in this area are picked up visually.<br /><br />Tilt your motor up, remove the trim tab (anode), remove the screw from under the trim tab, remove the 5 nuts (5/8" spanner) and the whole lot will end up in your lap. The driveshaft and shift shaft are splined. the water tube is just pushes into the rubber seal in the top of the impeller housing. When servicing the water pump look for signs of melting of the housing, burning in the cup inside the housing or burning of the blades of the impeller. If you reuse the impeller (not recommended but some do) DO NOT turn it over, install as it came out. Use a smear of grease inside the cup to aid putting the impeller in. Line up the key on the shaft and don't forget to use new gaskets. While you have the leg off, why not pull the prop and grease the shaft, and change the gear oil. Use a proper marine oil, not automotive. The best for the Mercs is their own 'High-performance Gear Oil'. I actually use this on ALL marine engines, everything from 2hp outboards to 500 hp stern drives. Putting the leg back on is a bit more tricky than taking it off. Make sure the leg is in neutral. That can take a bit of fiddling with the shift shaft. Grease the shift shaft, top of the drive shaft and the very end of the water tube (makes it easier to slide into the impeller housing). You may need to turn the crankshaft to get the splines to line up. I usually have the spark plugs out and it's easy to just push on the flywheel a bit. Make sure that the shift shaft and the water tube line up at the same time. That's probably the hardest part. After a couple of tries you'll find it and easy as putting a gearbox in an F-series Ford.
Refit the nuts you removed eariler and check that it selects forward, neutral and reverse as before. Then put the flushers on it and make sure you're pumping water into the powerhead. The next step is the most important..... sit back and enjoy and nice cold beer!<br /><br />Chris...........
