2004 Yamaha 25 gear oil leak

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  • April 28, 2018 at 12:08 am #9761
    outbdnut2
    Participant

      US Member

      Pardon the question here about a motor that’s only 14 years old, but my 2004 25 HP Yamaha 4-stroke (that my wife made me buy for my pontoon boat to quiet it down), has dripped some gear oil out over the winter for the first time. I can’t see in the back of the unlit garage where it’s stored exactly where it’s coming out until I pull the thing out in a couple weeks, but I can tell it’s not the propshaft seal – it’s coming from farther up.

      I’ve done a lot of seal kits in old OMCs but this will be my first Yamaha. Before I take it apart, are there any tricks/techniques I should know?
      Thx,
      Dave

      April 28, 2018 at 9:57 am #74920
      billw
      Participant

        US Member - 2 Years

        I never have done a 25 but have done some smaller and many bigger ones. They are pretty straight forward. They seem to like to leak out of the drive shaft seals a lot. Best bet is to pressure test before disassembly. Most Yamahas do one odd thing….the seal lips all face OUT. In other words, if you have back to back seals, they both are put in facing the same way. This is different than most other manufacturers and usually holds the pressure test figure down to about 9.9 psi.

        Long live American manufacturing!

        April 28, 2018 at 2:30 pm #74935
        Mumbles
        Participant
          quote outbdnut2:

          Before I take it apart, are there any tricks/techniques I should know?

          Before you even think about working on it, you’ll have to go out and buy, borrow, or steal some Metric tools.

          A 1/4" drive socket set with both Metric and SAE sockets will become your best friend, especially around smaller fasteners as found on carb and ignition components. A 3/8 drive socket set and a full set of spanners or box end wrenches should handle the rest. Deep sockets can be purchased as needed. At least your Phillips and slotted impact driver bits can still be used on the Yam.

          April 28, 2018 at 4:48 pm #74942
          outbdnut2
          Participant

            US Member

            Yeah – I’ve already had to buy the *#/&%* metric tools to keep my vehicles running, so I’m good there. Have deep 1/4 drive metric sockets too and they have come in handy many times.

            It’s probably the driveshaft seal. Thx for the heads up on the seal lip. I don’t have the right fittings to pressure test it, but I can put some pressure on it with my gear oil filler pump – that may tell me what I need to know.

            I was just thinking I should check first to be sure it isn’t the crankcase oil drain bolt leaking and dripping off the skeg – It uses a ringed flat aluminum washer as a gasket that is supposed to be replaced with each oil change – and I have never put a new washer on it. I’ll know more when I can get it out into good light.

            Changing spark plugs a few years ago was frustrating – no clearance around them for the thickness of the spark plug wrench. After going to several auto parts and tool stores, I finally found a deep socket that had thin enough walls to get the plugs out. The socket was made by AC-Delco/GM.
            Dave

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