The Boating Forum - Alpha I using drive oil
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08-12-2005, 08:38 AM
I have a '03 Merc 5.7, Alpha I with 38 hours. I have had to constantly top off the drive oil reservoir this season. I'm using the recommended Mercury high perf. gear lube. I don't see any signs of leaks anywhere. The bilge is clean, there's no drops in the driveway and no oil slick in the water. Could I be burning oil in the drive case? The boat tops out at about 52 mph on the speedo. The Alpha I is rated at a max of 300 hp and mine has 250 hp so it's well within the Alphas rating. Please help!!
08-12-2005, 04:13 PM
You aren't "burning" it up in the drive. If you don't have a drive shower, you may overheating the oil, but it isn't going to make it disappear. You should have water in your lower unit if one of the bottom seals is bad. You can check it by unscrewing the bottom oil screw in the drive just enough for oil to come out. If waters in there, it will be the first to come out. Depending on how much oil you have had to add, you might have a bad seal on the top end, where the yoke comes out and ties into the u-joints. The oil would just collect inside the bellows if it was leaking there. A pressure test of the drive will tell you right where it is leaking, but you will have to remove the drive to inspect all places.
08-12-2005, 08:47 PM
You may have a bad driven gear seal. There are two seals where the lower unit shaft enters the upper unit, and I screwed mine up by mixing high performance with premium gearcase lube :mad: The oil ends up going into the exhaust portion of the gearcase and out into the water. Mine didn't take on a drop of water, but I noticed oil coming out the weep hole by the front of the propshaft housing portion of the gearcase.
I'm a tinkerer, so I'm going to fix my drive myself - the tools will cost about $56, the parts about $25, and fresh lube is another $8. The Alpha is really quite a simple gearbox, so it's not that bad of a DIY job, if you have the tools and don't take too much stuff apart.
08-13-2005, 02:54 PM
I'm going with the input shaft seal on this one. In either case pulling the drive off and pressure testing is not that costly or difficult.
If you don't see any lube in the engine compartment or on the driveway then pull the gearcase off and check in the u-joint bellow area.* It could be sitting in there.