what all could cause x-rich black..Kohler 25.

Discussion in 'Mechanic and Repair' started by mowisme, Apr 11, 2008.

  1. mowisme

    mowisme LawnSite Senior Member
    Posts: 893

    I ran the Kohler today to move it..It now has a steady miss and steady dry black 'soot' out the exhaust? covers my tie with a dry black powder..like you'd get out of a fire place. Would this be: 1)carb 2)lifter's bad 3) bent push rod 4) loose rocker..these seem to be the trouble spots for this engine- Thanks -Geno P.S. The new coils have .012 air gap.
     
  2. Mic_bug

    Mic_bug LawnSite Member
    from N.B. MI
    Posts: 201

    choke stuck


    raw fuel from missing cyl
     
  3. VegetiveSteam

    VegetiveSteam LawnSite Senior Member
    Posts: 297

    What is the engine model number?
     
  4. mowisme

    mowisme LawnSite Senior Member
    Posts: 893

    The engine is a CV25S. The black 'soot' is not wet at all- black powder like. I meant to say in original post..covers my 'Tire', not 'Tie- I don't wear my Sunday best when working on mowers. Anyway- use to miss after warmed up..now misses almost from start. I don't think any 'unburned' gas is coming thru exhaust as it is dry black powder, not wet. Same on plugs. Seems VERY rich. I have tried cleaning carb - seemed like new inside. The choke is 'wide' open. I'm wondering if it could be 'Spark advance'?? I also don't think it is head gasket as that would create 'Lean' not rich..am I right on that? Any/All help appreciated. oh..would bad oil ring cause 'DRY' jet-black powder? Geno
     
  5. VegetiveSteam

    VegetiveSteam LawnSite Senior Member
    Posts: 297

    It could be the spark advance module but probably not. Don't see too many problems with that analog spark advance module anymore. One thing to check is the flywheel key. They don't shear very often on these types of engines but I have seen it. Especially if it ever afterbangs or runs on when you shut it off. That can partially shear the flywheel key and it doesn't take much of a dent in that key for the engine not to run well. To check the key you have to take the flywheel completely off. It is a woodruff key and without taking the flywheel off you can't see if it's sheared or dented. If you are going to check the key make sure you use a proper flywheel puller and do not hammer on the top of the crankshaft. If you do you just might find that you now have excessive crankshaft end play as hammering on the flywheel end of the crankshaft and cause the gear on the crankshaft to move.
     
  6. mowisme

    mowisme LawnSite Senior Member
    Posts: 893

    good thought Veg...and thanks on advice on removing flywheel. I won't do it without a proper puller..don't need more problems. Thanks- Geno
     
  7. MowerMedic77

    MowerMedic77 LawnSite Bronze Member
    Posts: 1,164

    Any chance you could post the spec# of the engine? I was thinking you may have a bad accelerator pump but would need the spec# to know if your engine is equipped with one.
     
  8. VegetiveSteam

    VegetiveSteam LawnSite Senior Member
    Posts: 297

    Good point Medic. Shame on me for not thinking of that.

    Mow...look on the side of your carburetor and see if there is a metal cover with 3 screws in it and a vacuum hose connected to it. There could be two vacuum hoses on it. If you have that on your carb pinch off or disconnect the one of the vacuum hoses and see if that changes your rich condition. If it does you have a bad pump diaphragm like Medic said. If that turns out to be the case you have two options. If you don't notice any transition issues from low to high speed and no hesitation when you get into deep grass you can simply leave the vacuum hose pinched off. If you disconnect it make sure you plug the hose securely. You don't want to pull any dirt into the carb. If you do notice a problem with hesitation then you'll need to change the diaphragm. Be forewarned though. That kit could be in the 70+ dollar range.
     
  9. mowisme

    mowisme LawnSite Senior Member
    Posts: 893

    the only hose is the one by air cleaner base going to canister above valve cover (PVC?..or..it just has filter foam in it)- I got it covered up out in rain right now so can't get spec# at this time..but am sure no vac hose going to carb. Had it off couple times. This motor appears to be a 'early' one as bit of crud on it at base..guess that don't tell thou.
     
  10. mowisme

    mowisme LawnSite Senior Member
    Posts: 893

    Well I took the flywheel off- The woodruff key looks fine. I may have a Accelerator pump after all- I knew there was only one hose going from carb to engine (PCV) BUT..today noticed there is a plate on left of carb as you are looking at it from the front (air cleaner end). this plate has three screws and is semi-cone shape and has a small hose going to top of carb near intake flange..is this a accelerator pump? (I know what acc pump is on older car carbs)- thanks - Please let me know ASAP as I am leaving shroud off until I eliminate that possibility. Gene (I will see if OM shows that on carb)
     

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