Oil reservoir leak on Merc 115

Discussion in 'Boats and Motors' started by Astro1700, Apr 21, 2008.

  1. Astro1700

    Astro1700 Member

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    I have a 1997 Merc 115 2 stroke with the oil reservoir connected to the engine under the engine cover. When I have oil in the reservoir (even under the recommended amount) and tilt the motor up to travel, the oil leaks out and gets all over the inside of the motor and then leaks down into the boat.

    Has anyone ran into this problem before and is there a fix for it. Thanks in advance.
     
  2. UFM82

    UFM82 The one others want to be

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    1) the reservoir cap is very prone to cracking. Most people have replaced theirs at some point in time. I had to get a new one right when I bought my boat several years ago. The slight air pressure in the system doesn't cause any issues until you tip the engine forward and it pushes oil out the crack in the cap. The cap is the level sender as well and had two wires running to it. It should be about $40 at the parts place.

    2) OR- the 2 psi check valve has died and it leaking oil. I just this year replaced mine. After a couple hours on the water I would start getting oil dripping down the transom. After cleaning the thing and running it I found a slight drip coming from the reservoir vent line that runs down the starboard side of my engine. ('93 Merc 150) That valve, a brass "T" fitting was $23 at the parts place.

    I'd bet on the cap though- your problem describes it exactly.

    UFM82
     

  3. DaleM

    DaleM Original OGF Staff Member

    Astro, I have the same problem with my 90 2003 Merc. The cap seems to be tight but as you said, when I tilt it it leaks out. I taped mine with silver tape to stop the leak. I'll be watching to see if anyone else has had this problem and how it was fixed. Thanks for posting this.
     
  4. I have the same motor,had the same problem.Baught a new cap fixed the
    problem.Also do not tighen the cap til it pops,just snug it down.

    Jeff
     
  5. UFM82

    UFM82 The one others want to be

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    It cracks right were the vertical surface joins the horizontal top surface. I couldn't see the crack either until I was advised of it. Once I knew where to look, I cranked down on the cap and Waa-Laa, the crack showed itself. Even then it was tough to see. However, if you take the cap off after you've run the engine, you'll hear the air pressure escape. It's that pressure that pushes oil through the crack and out onto your engine.

    Replace the cap and it will be fixed.

    UFM82

    Or tape it- whatever works...
     
  6. Astro1700

    Astro1700 Member

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    Thanks for the info everyone. I'm going to replace the cap.
     
  7. my 95 75hp does the same thing