1957 Sea King 12HP won't run right

Home Forum Ask A Member 1957 Sea King 12HP won't run right

This topic contains 24 replies, has 9 voices, and was last updated by Avatar fleetwin 3 days, 23 hours ago.

Viewing 15 posts - 1 through 15 (of 25 total)
  • Avatar
    huntleybill
    US Member - 1 Year
    Replies: 208
    Topics: 79
    #173035

    Got my Sea King put back together but it doesn’t run quite right. In order to get the motor to run well, the choke has to be closed between 1/2- 3/4. If I open the choke, it will sneeze and die. Seems to me there is a leak somewhere (maybe???). I tightened all the block bolts, head bolts, screws. Compression is 75 psi on both cylinders. I don’t have a parts manual for this motor so I don’t know if there is a seal leaking and if so, which one, and what the part number would be.

    This would be a sweet motor if I can get it to run right. Any help on why this is happening would be appreciated.

    Thank you
    Bill

    frankr
    frankr
    US Member - 1 Year
    Replies: 3996
    Topics: 43
    #173042

    A crankcase leak might be a valid guess, but probably not it. I’d sooner say the slow speed circuit in the carburetor is blocked. Or the carb butterfly is opening way too soon. Or the main bearings are worn out–but you would have noticed that, right?

    Avatar
    huntleybill
    US Member - 1 Year
    Replies: 208
    Topics: 79
    #173048

    Well, I went through the carb twice because I first thought it was a carb issue. One thing I forgot to mention was that I put about a half gallon of fuel in the tank and it sucked that down in about 15 min. I have the timing of the butterfly to open just as the the lever gets to the mark. There is no knocking so I am assuming the bearings are ok…or am I wrong. Could air be leaking past the bearings causing a lean condition that would require me to close the choke to draw more fuel? Hence going through more fuel than I think I should?

    If that is the case, would you have part numbers for bearings/seals?

    frankr
    frankr
    US Member - 1 Year
    Replies: 3996
    Topics: 43
    #173067

    OK, first let me say that there were two 12hp motors for 1957, the “Standard” and “Deluxe”. Most obvious difference was the Standard has an integral gas tank, Deluxe has a remote gas tank. There are many other differences also. Give me a model number and I can post the parts list.

    Back to the seals question, the Standard doesn’t even have any seals. It relies on the long cast-in bronze bushings to create enough seal–and does it quite well unless they are worn out. The Deluxe has a different exhaust housing, which necessitated adding a seal on the lower end of the crankshaft to keep water out of the crankcase (not to keep pressure in).

    About that seal: As I said, it is to keep water out. The motor will run very well with a bad seal, which is a problem because water is getting in un-noticed, which will cause it to throw a rod. Worse, the 303804 seal was garbage and failed often. It is what trashed many a motor in the day.

    Waiting for a model number.

    Avatar
    huntleybill
    US Member - 1 Year
    Replies: 208
    Topics: 79
    #173072

    Thank you Frank. GG9016A. Mine has the onboard fuel tank. By your explanation then, it would seem that a seal is not the cause of my problem. So, I guess I am back to my original question about what may be causing my problem. Thank you for copy of the manual. It will come in handy. Also, thank you for your advice.

    frankr
    frankr
    US Member - 1 Year
    Replies: 3996
    Topics: 43
    #173076

    Surprise, 9016A is a 1954-55 12D11 Deluxe. The Deluxe became the Standard in later years when the remote tank came into being and became the new Deluxe. Confused yet?

    Anyhoo, here ya go—-

    • This reply was modified 1 week ago by frankr frankr.
    Attachments:
    frankr
    frankr
    US Member - 1 Year
    Replies: 3996
    Topics: 43
    #173081

    More—-

    Attachments:
    frankr
    frankr
    US Member - 1 Year
    Replies: 3996
    Topics: 43
    #173087

    Lastly—-

    Attachments:
    Avatar
    bayham3261
    US Member - 1 Year
    Replies: 28
    Topics: 4
    #173094

    Hi! I’d agree without pulling everything apart it sounds like a carb issue. definitely check for blockages in the low-speed passages. I’ve had similar issues with miss-adjusted floats. If the float isn’t performing correctly sometimes the bowl won’t fill up enough to allow the weak low speed suction to work properly. operating a half choke will increase the suction to pull fuel. I’d also check to make sure your needle packing… a complete go-thru of the carb before you start chasing other possibilities.

    A little information is a dangerous thing!

    Avatar
    huntleybill
    US Member - 1 Year
    Replies: 208
    Topics: 79
    #173096

    Thank you Frank.

    I will go back through the carb. I replaced the packing, but I did not replaced the float. I’m not sure I understand why the low speed needle may be clogged as it does not matter what speed, the motor is at (either high or low), the condition still occurs.

    olcah
    olcah
    US Member - 1 Year
    Replies: 293
    Topics: 65
    #173106

    I have a 1956 12 HP Sea King (very similar motor, remote tank). It ran skipping stumbling etc and was not sensitive to the carb needle settings. Although I had replaced the needle packings the motor needed additional packings on top of those already there. I think it was drawing air past the packings and running lean. Ran beautifully after that and was sensitive to the carb needle adjustments. Suggest you try adding some packings first. Good luck.

    Avatar
    bayham3261
    US Member - 1 Year
    Replies: 28
    Topics: 4
    #173107

    I wouldn’t initially replace the float unless it is damaged. If it is cork you can reseal it. Generally speaking if you take the float bowl off and turn the carb upside down the float will rest in a fully closed position. This position dictates the height of the fuel in the float bowl. There should be a measurement you can find in a tune-up book that will indicate the distance between the float and the upper carb/bowl flange surface. To adjust the float height you carefully bend the needle valve tab with a pliers. Do not push down on the needle to bend. This is an adjustment that needs to be checked every time you clean a carb or replace a float. Brand new floats can be out of adjustment.

    I don’t have a measurement for this carb float… maybe another member would know. Sometimes carb floats are designed to just be parallel with the carb bowl flange.

    I’ve also heard about people installing floats upside down by mistake and having similar symptoms… goofy these things happen to the best of us!

    If you’ve gone through the carb and everything is good, then look for cracks or poor fitting gaskets in the intake and block. A little light grease can seal cracks long enough to test. If the grease fixes your problem… you know where the issue is with an air leak.

    If you have an air leak I wouldn’t expect that it would be at the crank unless it is worn out as mention previously. The old oil slinger style design on the crank top is generally looked as being reliable. I have heard that some other outboards rely on heavy oil mixes to provide a seal… theoretically if you were running a very light mix it could possibly occur on this type of motor as well.

    A little information is a dangerous thing!

    Avatar
    bayham3261
    US Member - 1 Year
    Replies: 28
    Topics: 4
    #173125

    I found some instruction in an old repair manual… The float just needs to sit parallel.

    A little information is a dangerous thing!

    Avatar
    bayham3261
    US Member - 1 Year
    Replies: 28
    Topics: 4
    #173126

    here’s the instructions

    A little information is a dangerous thing!

    Attachments:
    Avatar
    garry-in-tampa
    Lifetime Member
    Replies: 3008
    Topics: 29
    #173150

    This is what I haveĀ . . .

Viewing 15 posts - 1 through 15 (of 25 total)

You must be logged in to reply to this topic.