Water blockage?

Discussion in 'Outboard Maintenance' started by Mattcorrell, Aug 27, 2014.

  1. I have a 89 yamaha 15 hp. I just replaced the ware pump, thermostat, spark plugs and so on. I noticed I have water coming out of the pee hole but no water coming out of the thermostat hole below that. I've looked at some old posts and put the thermostat in boiling water and it opened. I removed the thermostat housing and blew air and water in the passage to see if I could blow some junk out. Water came out the prop but not the second hole. I shot water in the hole from the outside and it came out the prop but not up at the housing. It seems like I'm still getting water through the head just not out of that high exhaust port. Do I need to worry ?
  2. MariettaMike

    MariettaMike Wish'n I was Fish'n!

    What thermostat hole below the pee hole?

    If you're talking about the hole in the back between the lower unit and the engine, I don't think water can ever come out there unless you're prop is plugged and the water pump intake isn't. That hole is only for relieving exhaust pressure when the exhaust back pressure is high like when you're not moving or in reverse.

    The thermostat controls water flow through the engine only. When it opens that water goes out the exhaust along with all the other water that is flowing through the exhaust manifold. The pee hole water proves that the water pump is pushing water through the top end of the exhaust manifold cooling system and keeping the exhaust manifold cool at all times regardless of the engine thermostat position.

    Don't worry.

    DISCLAIMER: I'm not a technician, just an engineer making observations from Yamaha schematics and past experience with a variety of engines.

  3. http://i46.photobucket.com/albums/f118/ma2ts/09C9D557-8D02-489B-B62C-E13D7AE50FEB_zpsdwbs392x.png

    I downloaded the manual last night. It shows water coming from that area. But like you said I can see the water coming out of the prop so water is flowing. I posted a pic out of the manual.
  4. MariettaMike

    MariettaMike Wish'n I was Fish'n!

    I have a 2002 Yamaha 2 stroke 90 and the only thing I have ever seen come out of that hole is smoke when I start the engine. Though I recall seeing a small amount of water coming out on one of my old 80's vintage Mercury short shaft engines.

    Without seeing a connection between the casing and the engine or exhaust I don't see how water could ever come out there unless something is wrong.


  5. cutrunner

    cutrunner Cert. Yamaha technician

    You dont have a problem.
    water can come out of those holes when the motor is really low in the water and it raises the backpressure in the exhaust.
    some motors do, some dont. Depends on the setup
  6. Good news! Thanks guys. Going to put her in the bay this morning!