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Kohler 25hp problem. Help please?

Discussion in 'Mechanic and Repair' started by mcambrose, Jul 18, 2005.

  1. mcambrose

    mcambrose LawnSite Senior Member
    Messages: 518

    Have a 25 hp kohler which has 1600 hrs. When it is warm and you idle it down and then give it full throttle it gives out black smoke and lugs down for 10 seconds to a minute. I have checked both coils and the SAM. The head gasket was replace a couple of hundred hours ago, but it seems like it acted kind of like this before the head gasket was changed. When it does reach full rpm it seems pretty strong. It does burn about 1 oz of oil per hour. Also, it you put it in a side hill it will cut out on me. Any suggestions are appreciated.
  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    From what you are describing it sounds like the accelerator pump isn't working properly, It may be time to rebuild the carb. but a carb. rebuild kit doesn't come with the accelerator pump thats a separate kit.
    I'm sure if it were another blown head gasket the smoke would be blue instead of black. I just pulled one down today with a blown head gasket, Pull the plugs out and see if one has black oily carbon build up on it, That would indicate a blown gasket. If they both look black with no sign of oil it will probably be a carb. problem. And this mite just strighten out your hill side issue also.
  3. mcambrose

    mcambrose LawnSite Senior Member
    Messages: 518

    Thanks for the reply. I will run your suggestion by the Kohler tech support to see if they concur. It sounds reasonable to me. How much trouble is it to replace the accelerator pump. I couldn't find a good parts breakdown. There is one in the j-thomas catalog, but the carburetor portion is not large enough.
  4. fixer67

    fixer67 LawnSite Silver Member
    Messages: 2,098


    and use the Guest login to the right of the Dealer login. You will need your spec number
  5. mcambrose

    mcambrose LawnSite Senior Member
    Messages: 518

    Thanks. I tried the site and it is good.
  6. Redneckn

    Redneckn LawnSite Senior Member
    Messages: 294

    Fixer, have y'all seen many of the cv730 type Kohlers with breather reed and head gasket issues?
    It seems as though there has been a surge in those over the last 2-3 months.
  7. fixer67

    fixer67 LawnSite Silver Member
    Messages: 2,098

    I have not seen any CV730 in the shop at all. Only a few LH785. Most what we get is CV 17-25 and CH18-25 and CH26 EFI. We also see a lot of the older "K" series as well. I know a few years back there was a problem with the head gaskets on the 25's but that has long since been fixed. It may be alone the same lines as what you are seeing.
  8. mcambrose

    mcambrose LawnSite Senior Member
    Messages: 518

    I finally gave up on this engine. I tried a new carb and the problem wasn't fixed. I decided it wasn't worth the aggravation. I replaced with a Ch730 and the power is great. Maybe I now have a few spare parts. Thanks for everyone's input on trying to solve the problem. I think the problem was ignition breakdown under load, but with the age of the engine, I think I was just flushing money down the toilet. Thanks again.
  9. Brianslawn

    Brianslawn LawnSite Silver Member
    Messages: 2,004

    should do leak down test. im wondering if rings were worn. oh well. good luck
  10. i_plant_art

    i_plant_art LawnSite Senior Member
    Messages: 558

    ive got a kohler 23 hp still under warrenty it was doing the same thing recently ( like 2-3 weeks ago) it would run til it got in thinck gras then cut out some bog down almost as if the choke had been turned on in mid run....... i thought the coils were bad too it to the dealer since it was still under warrenty and it ended up that the carb was just running too rich... just needed a little adjusting to it..... got it back havent had a problem since ............ hopefully this willl help ya out.

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