missing lack of power fouling one plug Kohler

Discussion in 'Mechanic and Repair' started by bdamon, Apr 18, 2007.

  1. bdamon

    bdamon LawnSite Member
    Posts: 7

    I have a Kohler, model number CV740S 2004 twin cylinder vertical shaft that is fouling the left plug, black soot, misses, when you shut it off it back fires. Performed a cylinder leak down test when air put into the suspected bad head, I can hear air coming out of opposite head and crank case. Compression test I have 165PSI both cylinders was told possible cracked head.

    Does anyone else have any suggestions or believe that this diagnose is true.

    Thanks
    Brandon
     
  2. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    Head gasket
     
  3. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    Did you use a leak-down tester or just plug a air hose up with 120 lbs. of air ?
    Where exactly is the air coming from on the other cylinder ? (head gasket area, intake or exhaust)

    If it were a head gasket the plug would be wet and oily or you would have a oil leak in the gasket area on the outside.

    Sounds to me you have a coil thats not firing or firing weak. Have you tried another spark plug ?
     
  4. bdamon

    bdamon LawnSite Member
    Posts: 7

    i used a leak tester at 30 psi and 80 psi left cyclinder ,the air comes out the ather cyclinder,by the sound comes from the area of the push rods and rockers.i have put a new coil and new plugs no fix
     
  5. bdamon

    bdamon LawnSite Member
    Posts: 7

    thankyou for your help i am new to this site.i have worked for gm for 20 years
    the cars are easier.the leakage is from the ather cyclinder at any psi. with
    a leak down tester. the plug is black sooted dry after 5 min of operation.no leakage found around head,what about the spark advace module that goes to the coils. thank you for your assistance i am stumped!!!!
     
  6. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    did you take the head off?
     
  7. bdamon

    bdamon LawnSite Member
    Posts: 7

    not yet thanks i will let you no thanks,i still am thinking about that moduel on the side
     
  8. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    Below is the only test the average person can perform on the SAM module. Other testing requires a special tester. Make sure you have at-least 7.5 volts on the red main feed wire going into the SAM in run and start positions. REMOVE the black ground wire coming out of it and check for corrosion on the connector and screw. Also check BOTH coils at the wire connectors AND mounting screws for corrosion.


    [​IMG]
     
  9. Bill Kapaun

    Bill Kapaun LawnSite Senior Member
    Posts: 911

    "the air comes out the ather cyclinder,by the sound comes from the area of the push rods and rockers."
    That's typically where the head gaskets blow.
    There is only a very thin gasket area between the cylinder and the push rod galley.

    Here's a link to the service manual if you don't have it-

    http://www.kohlerengines.com/common/resources/tp_2450_b.pdf
     
  10. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    Guy's,

    When a leak-down test is performed a certain amount of air passes the rings into the crankcase. Once the crankcase is full of air a certain amount of air will bleed out through the breather system and the oil return passages in the head.

    This would account for hearing air around the push-rod area on the opposite cylinder being tested.
     

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