1980 40hp Merc Thunderbolt oil problem

Discussion in 'Bubba's Outboards' started by vegasryder, Nov 20, 2006.

  1. vegasryder

    vegasryder New Member

    Messages:
    324
    State:
    illinois
    Just need a little input from you guys/gals...I have a 40hp Merc Thunderbolt and have an oil issue.While changing the gear lube,i noticed the oil color was a mocha/coffee with creamer look.Anyone have any ideas on what the problem may be?I`m guessing the oil got mixed with the water but you opinions are welcome.Does the seals need replacing?The motor starts ryte up and it goes into all the gears.
     
  2. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    I would change the little seals that are behind the fill and drain screws and see if anymore water entered it. If it doesn't then you found the problem. How long has it been since you changed the oil. After a couple trips I would check it again after changing those two seals.
     

  3. vegasryder

    vegasryder New Member

    Messages:
    324
    State:
    illinois
    I never had a chance to take the boat out since i purchased it last month.I really dont have to much info on when the boat was last used because i bought it off some guy that had it as a consignment.Worse case scenario...if what you suggested is not where the problem is originating from...where else would it be coming from?I know its hard to say without looking at it,but any suggestion would be good.This would help me decide if i`m going to tear the motor down for the winter and go through everything(which would be a smart move).Also...would checking the compression on this motor be the same as checking the compression on a car?
     
  4. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    The oil could be entering thru the prop shaft and shift shaft going into the lower unit. I know those kind of deals and have made quite a few of them myself. Sometimes you make out and sometimes you don't. If this is all you have found then its small potoatoes to say the least. If you have a warm place to work then take the lower unit off and set it in a container big enough to get water up over the pump and take you a bycycle pump and put it in the top screw and pump you some air into it and see where its leaking.

    Then you will know for sure. It won't take much air and you will see little bubbles coming from where the seal is leaking. Drain the oil out first though. and put the lower plug back in and remove the prop to make it easier.
     
  5. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    I'll post a picture of the lower unit and you can see what I am talking about. BTW is that a 2 cylinder or a 3 or 4 cylinder


    If you can get me the serial number off it and I can see what exactly we are dealing with here.
     
  6. vegasryder

    vegasryder New Member

    Messages:
    324
    State:
    illinois
    you got a pm and a rep.thanks brother!!!
     
  7. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    Kenny there are two seals involved under the housing of the lower unit accessible from the top while lower unit is removed.

    # 1 is the shift shaft seal seierra part number 18-2009

    # 2 is the seal located under the water pump part number 18-2055


    The shift shaft is easy to take apert and install the seal as is the water pump seal. Now if you don't know when the last time the water pump was changed then I would go ahead and install a whole complete water pump for peace of mind. They may seem pricey but are cheap compared to a power head from over heating.

    Here is the diag of the placement of the seals.
    http://img.photobucket.com/albums/v172/coofficer/Picture119.jpg?t=1164146431
    If you decide to replace the water pump then let me know and I'll run down the parts number for you. You can purchase these items at any Orileys or NAPA parts store. You might have to down load this picture and enlarge it or pm me your e-mail addy and I'll e-mail it to you.
     
  8. vegasryder

    vegasryder New Member

    Messages:
    324
    State:
    illinois
    A couple of questions...Now looking at the picture,If i was to replace the water pump,would it be parts 10-27 and 41,42?My guess that this is the water pump assembly.Also...Can you tell me which is the shift shaft seal?Would it be #36(oil seal)?And the seal under the water pump...would it be #13 and #14 which are both oil seals?I will most likely replace the water pump since i dont have any clue if it was ever replaced.Better to be safe than sorry..So if you could,please send me the part numbers if you have time.Thanks again and i appreciate you help.
     
  9. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    The oil seals will have to be purchased seperatly from the water pump.

    On the diag # 36 will be the shift shaft seal # 18-2009

    # 13 and 14 on the diag will be the seals below the water pump part number 18-2005 and 18-2011

    The water pump kit will be 18-3324 that will give you a new water pump from base up.

    When you get it apart it will be more clearer to you. They aren't that hard to change and Bob and I will be right here if you have any trouble.
    Just go to an Oreily's parts store or a NAPA store and they can get these things. I have found Oreily's to be some what cheaper
     
  10. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    One seal I forgot was the little ones around the drain and fill plug 18-2945

    Now as for the seals you can buy them in a kit with all the gaskets and seals plus a few extras that god only knows what they fit and that number would be 18-2654

    Hope all this helps instead of cornfusing you.:big_smile:
     
  11. vegasryder

    vegasryder New Member

    Messages:
    324
    State:
    illinois
    No your not confusing me...it doesnt look complicated at all.I`m a look at the picture and do it kinda guy.I was never into reading and trying to figure out what the heck i`m suppose to do_One thing though...when you say Napa,i`m assuming the auto parts store,rite?I never thought of them selling outboard parts...Thanks again for your help!!!