12.5 won't start?

Discussion in 'Mechanic and Repair' started by Shady Brook, Dec 26, 2001.

  1. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    Did you do everything that I outlined above? The "combustion chamber" cleanout is included in my instructions.
     
  2. Shady Brook

    Shady Brook LawnSite Bronze Member
    from Indiana
    Posts: 1,517

    Richard

    Yes, thank you for the great post. I did what you said over several times. I continued to get oil in the carb after it all. But I wonder if maybe the timing might be the issue, or part of it. Could you give me instructions to check the timing to elimate that as well? Thanks
    Jay
     
  3. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    Bear in mind that checking cam timing this way is no guaranty that the cam timing is right. It will only tell you if it's grossly off.

    One way is with a compression gauge. Put the gauge in the engine and give the engine a few pulls. If the compression is low (20 to 30) then you may have a problem with cam timing.

    The second way is a little more work but a lot more reliable. Pull the head off and slowly rotate the engine clockwise until you see the exhaust valve open. The piston should be headed up in the cylinder. Keep rotating the engine until the piston reaches the top of it's cylinder. At this point both valves should be closed. Now continue rotating the engine. The intake valve should open as the piston heads down in the bore and then close as the piston reaches the bottom of the cylinder. For the next up and down cycle both valves should remain closed. Then the whole process starts over again.
     
  4. cnflawn

    cnflawn LawnSite Member
    from tn
    Posts: 55

    hi
    i know this sounds silly but ive been there already.
    remove 2 nuts at head that hold muffler on. move muffler enough that gas oil mixture will run out. its there believe me. pull plug . pull engine over several times. install plug and restart. dont feel bad it is very aggrevating. you can test this problem by doing a leakdown test and youll notice no air coming out when the exaust vale is open.
    jerald
     
  5. Shady Brook

    Shady Brook LawnSite Bronze Member
    from Indiana
    Posts: 1,517

    Jerald

    I have had that muffler off cuz I thought the same thing. I did not have any oil come out of the muffler, and did not see any oil draining out of the engine from there either.

    I am thinking more and more it is beyond the oil issue. I will look into the compression test, thanks Richard.

    If it is timing, would it act like it wants to start better when using starting fluid and such?

    Thanks
    Jay
     
  6. cnflawn

    cnflawn LawnSite Member
    from tn
    Posts: 55

    hi again,
    sorry that didnt work, will you please do a compression and a leakdown test and let us know the results. the possibility is you bent a valve with oil in the cylinder. the 12.5 has push rods and no overhead valves so you can pull the head pretty quick to check operation of the valve train. unless youre 400 lbs of pure muscle i dont think youll shear that flywheel key by pulling the rope. the above thought is assuming everything went back in correctly. i hope you fix it quick because that 12.5 on a 36 scag is a great unit.
    jerald
     
  7. Shady Brook

    Shady Brook LawnSite Bronze Member
    from Indiana
    Posts: 1,517

    Thanks cnflawn

    I sure will let you know what I find out. Could you give any pointers on the process of pulling the head, and what to look for when inside? I did not get to try the timing out, but maybe this way I can kill two birds with one stone. My PSD won't start! Always something! I am in the process of charging the batteries, and I have the block heater in, so hopefully I can get her going tomarow.

    Thanks again
    Jay
     
  8. General Grounds

    General Grounds LawnSite Senior Member
    Posts: 902

    :blob3: Shady B, when you put the engine back together did you use a feeler gauge in mounting the coil, you may be a little to far away and not getting proper or spark at all, you may also have a bad ignitor which is mounted on the outside of the engine and is about 1"x1" this could aslo be bad, if you have another kawi try borrowing from the good engine b/c an ignitor is an expensive part if were not sure. Tony
     
  9. Shady Brook

    Shady Brook LawnSite Bronze Member
    from Indiana
    Posts: 1,517

    Tony

    I did not use a feeler gauge, nor do I even know what it is. :) Should I have used one? Can you give any more info on how I can check this? Where is the ignitor, can you describe it for me?

    Thanks
    Jay

    PS. I did use a spark tester, and was getting spark, not sure if this is what you mean though.
     
  10. cnflawn

    cnflawn LawnSite Member
    from tn
    Posts: 55

    hi jay,
    man i hate to hear about the power stroke. i thought they would crank anytime. i had the old 7.3 they were a chore but my ps has never let me down. as to remove the head just take the sheetmetal off the front and top. take the head bolts out. make sure to remember where the bolts come from as some are different. slowly rotate engine CW using flywheel nut. watch valves open and close. the intake valve should open about about 1/4 inch followed by the exaust valve (bottem one). in between they both should be closed completely. good luck with the ford.
    jerald
     

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