Hot warning horn on Yamaha C115

Discussion in 'Bubba's Outboards' started by scout, Sep 24, 2006.

  1. scout

    scout Active Member

    Messages:
    769
    State:
    Louisiana
    Hey Bob, how are you? Well I hope.

    After 10 years of trouble free service from my 1997 Yamaha C115 which I purchaced new in 1996, I have got my first problem. I am getting a hot horn above 4000 rpms. Once I get back to idle the horn goes off in about 15 seconds. I went ahead and changed the complete water pump and both thermostats. I took it for a test ride today and it still gets the hot horn at above 4000 rpms. Do you think it could be the thermoswitches (I think that is what they are called)? I removed them from the power head and they are not corroded. I have checked in every possible place for blockage but did not find any. Is there anything else that could be causing this problem? The engine is pretty basic without oil injection and runs great. Thanks in advance, Randall Duhon.
     
  2. Bobpaul

    Bobpaul New Member

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    Randall, good to hear from you, wish you were trouble free though.

    I don't have an answer right now for you. Knowing your mechanical ability, I'm assuming you put all the parts back in the water pump, in order.

    Try running the engine on the hose with the thermostats out, and let the block flush. Take notice that the water coming out has no large amount of bubbles in it and comes out with good force.

    I'll check further on your problem tomorrow.

    It's a new one for me too.
     

  3. scout

    scout Active Member

    Messages:
    769
    State:
    Louisiana
    Thanks for the quick reply Bob. Although I have changed the impellar blade a few times myself, I went ahead and let the pros change the water pump for me. I brought them the lower unit and the local Yamaha dealer changed it for me. I purchased the thermostats and installed them myself. I have the same exact problem that I had before any of this work was done.

    Do you think those thermoswitches could go bad? There is one on the top of each cylinder bank close to where the thermostats are located. I think that is what sends the singnal for a overheat.

    I will try what you said about removing the thermostats and try and flush the motor. I may have to bite the bullet and bring it to the shop lol:crazy: . Thanks for the help, Randall.
     
  4. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
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    Randell if that horn is where you can get to it, disconnect the tan wire from it and see if it still sounds when you fire it up like you have been doing then the horn itself is bad. Just something to try before pulling those sensors
     
  5. scout

    scout Active Member

    Messages:
    769
    State:
    Louisiana
    Bubbacat, do I pull the tan wire after I get a hot horn while running the boat, or do I pull the tan wire before I start the motor and listen to see if the horn goes off when I do start it up? Thanks, Randall.
     
  6. Bobpaul

    Bobpaul New Member

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    Randall, if it's where you can get to the wire to unplug it, I'd say after it goes off.

    I'm still thinking you have a blockage in one of the heads though, and it was also the thoughts of another mechanic I talked to today. Try checking your water output from the thermostat openings first on the hose.

    He thought you should pull the heads and be sure. It's fairly easy to do, but you'll need two new head gaskets.
     
  7. scout

    scout Active Member

    Messages:
    769
    State:
    Louisiana
    Hey Bob, it is funny you say that. I talked to my friend who is a mechanic here at our local boat dealer and he told me the same thing. I think I will try and removing the heads and look for blockage. He told me he has run into this problem before.

    Yesterday I removed the thermostats and ran it on the hose. I also removed the water hose at the base of the block and checked for any blockage and did not find any.

    I also removed both thermoswitches and checked them as per the maint. mauual using hot water and a ohm meter. They work fine.

    The local mechanic told me to take it out on the water and test it again with a portable digital thermoter. He told me to run it again until the horn sounds and check the temp. at the top of both heads. Then switch the thermoswitches arouynd and try again.

    If this not work I will remove the heads and seewhat I can find.

    I also will try removing the wire from the horn and checking that out.

    Thanks for the help, Randall Duhon.
     
  8. Bobpaul

    Bobpaul New Member

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    Randall, when you find the cause of that gremlin problem, let us know please.
     
  9. scout

    scout Active Member

    Messages:
    769
    State:
    Louisiana
    I sure will Bob. My Fall fishin season is starting and I need to get the old Yamaha right:confused2: . I will stop by my local dealer and pick me up a couple of head gaskets so I will have them when I am ready to do the job. Thanks, Randall.
     
  10. scout

    scout Active Member

    Messages:
    769
    State:
    Louisiana
    Hey Bob, I finanally had the time to remove the head covers (water jackets) from my motor. You were right there was quite a bit of crud buildup especially around the passages around the thermostats. I cleaned everything up the best I could. Our local dealer did not have the gaskets in stock so they are on order. Should be early next week.

    I always flush my motor after I go fishing, but my mechanic friend at the boat shop told me after 10 years of salt water use it is not unusual to have this problem.


    It is real bad timing to have this problem especially with this beautiful weather. but at least it did not leave me on the water lol. And I shouldn't complain after getting 10 years of trouble free service before my first problem.:roll_eyes:

    Well I hope the next time I talk to you I will have my motor back in operation. Hopefully this will fix the problem. Thanks for the help, Randall.
     
  11. Bobpaul

    Bobpaul New Member

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    I'm sure it'll help. That build up insulates the heat into the engine and won't allow the water to carry the heat out.

    Hopefully it's a final fix.
     
  12. trnsmsn

    trnsmsn New Member

    Messages:
    1,214
    State:
    Missouri Originally Now I
    Good Morning Bob, have you ever taken the thermostats out & ran the motor in a drum with Tidy Bowl (toilet cleaner), to flush out the crud ?

    I've done it several times with success:eek:oooh:
     
  13. Bubbakat

    Bubbakat New Member

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    4,532
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    What Elliot suggest does in fact work and they also make a product called salt away that will do the trick to.
     
  14. Bobpaul

    Bobpaul New Member

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    No I've never tryed those remedies, although I don't see how they wouldn't work.

    I know that vinegar will take concrete sludge off of painted cars, that has dryed, and will clean the deposits out of drip coffee makers. I've always wondered how running an engine in a tub of vinegar would work:roll_eyes:

    I like the tidy bowl idea.
     
  15. scout

    scout Active Member

    Messages:
    769
    State:
    Louisiana
    Hey Bob, I will probably be putting my motor back this coming week if the gaskets come in. Should I put the gaskets on dry or use some gasket sealer on them before I install them? It looks like the ones that I removed had some sealer on them insatlled at the factory. Thanks in advance, Randall.
     
  16. Bobpaul

    Bobpaul New Member

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    Randall, no sealer is required for those gaskets. They come with a sealer impregnated surface, sorta sticky on both sides.

    Torque them done in two stages following the numbers on the heads for the sequence. I'm not sure of the torque values, but any dealer can give them to you.

    If the heads aren't numbered, just start in the middle and circle your way around untill you get to the top and bottom bolts.
     
  17. Bubbakat

    Bubbakat New Member

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    4,532
    State:
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    Do Not use any type of sealer on outboard carburetor or intake manifold gaskets as this would cause blockage of various fuel/air passageways. Also, there are new type gaskets, including head gaskets, which are used through out the engines that are coated with a substance that gives a shinny appearance to them. These gaskets are coated with a self sealer and are to be installed as is.... no sealers! Older style head and fuel related gaskets that are not coated with this substance are to be simply coated with oil.... nothing else.

    All other gaskets (hopefully I've not overlooked anything above) should be coated with Gasket Sealer (the type that comes in a can that has a small brush in its screw off cap). This also pertains to some water pump installations that use a gasket between the plate and the lower unit housing.

    Marprox Sealer 1000 or OMC Adhesive or Boat Armor Sealer 1000 (same substance) should be used on any metal to metal or metal to plastic surface (such as impeller hsg to plate) to eliminate air leaks. It should also be used on the Spaghetti tubing that is used on many powerhead crankcase halves, lower unit skegs, etc. I have found that this substance works quite well on various "O" Rings such as what are found on lower unit carrier and upper driveshaft bearing housings (Note that this substance is obviously not to be used on all "O" Rings).

    DO NOT use any sealer on the large "O" Rings that are used on the upper and lower crankcase heads (The housing/heads that slide over the top and bottom of the crankshaft). On those "O" Rings, use only a coating of grease.

    The exception of surface to surface contacts pertains to the later model matching crankcase (block) halves (which does not incorporate spaghetti tubing) which call for "Gel-Seal", or any other surface that calls for Gel-Seal. This substance seals in the absense of air, and if called for, must be used. One other form of Gel Seal that can be substituted is "Loctite #518". Nothing else that I know of will do!

    I advise against using silicone or permatex
     
  18. scout

    scout Active Member

    Messages:
    769
    State:
    Louisiana
    Thanks Bob and Bubbacat. That explains the sticky substance on the gaskets that I removed. Bob The motor has the torque and sequence numbers stamped on the covers. Thanks again for the help guys. Man I can't wait to get back on the water:smile2: .
     
  19. scout

    scout Active Member

    Messages:
    769
    State:
    Louisiana
    Hey Bob and Bubba. I finally got my gaskets Friday. I installed them and ran it on the hose and everything looked fine. I also bought some salt away any gave the motor a couple of treatments. I took it out today on the water and everything went fine, no more hot horn. I really want to thank y'all for the help. I will be using salt away from now on. It sure is nice to be back on the water. Thanks, Randall Duhon.
     
  20. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    You are very welcome and aren't we always happy when a plan of attack comes together.:cool2:

    Thanks for the follow up and have fun now and catch the biggun.