Yamaha 15hp 4 Stroke -- Water in Motor Oil

Discussion in 'Outboard Maintenance' started by Hsteele, Mar 25, 2015.

  1. Hsteele

    Hsteele I Love microskiff.com!

    I have a 2005 Yamaha 4 stroke 15 hp outboard that recently started getting water in the motor oil.

    The motor was acting up the last time that I ran it, so I decided it was time for some routine maintenance. The lower unit oil was perfectly golden, but the motor oil definitely had water in it.

    When I hook up the water hose to the backflush nozzle on the motor and cover the pee hole, water drains out of the motor oil drain hole. I also ran a compression test on each cylinder, and both cylinders put out 30psi (at normal cranking/starting throttle).

    Anyone have a similar issue in the past or have any advice on what's causing the problem? The two shops that I've called said it could be a number of things, but I wanted to check here first.


  2. noeettica

    noeettica Well-Known Member

    Sounds like a blown head gasket

    That motor is very durable so that should not have Not happened ...

  3. DuckNut

    DuckNut Brandon, FL

    I agree with Noe

    But 30 psi seems way low. Most are around 100. I am no expert by any stretch of ones imagination.