Kohler 27hp. Running rough, Gas in oil

[mcat2197]

Hi All, this is my first thread. I have a 27 hp Kohler cv740. It runs rough and blows some blue smoke at start but then small amount of black smoke.. Plugs are black as could be. There seems to be excessive amount of blow by come out the oil tube. It's getting spark. I checked the needle and seat. Checked the Fuel cutoff solenoid. all seems ok. Someone said it looks like the carb is dumping gas into motor causing wash down of cylinders but would that explain the blow by ????? Is there anything else I should check before I open her up and change the head gaskets?

 

[Scrubcadet10]

it could either be the needle failed and is not controlling flow into the carburetor bowl or if it has a vacuum operated fuel pump that could also be allowing fuel into the crankcase through the vacuum line. But you saying the plugs as black as they are im willing to bet the needle isn't sealing, or you have a hole in the float.
and just to add ,the fuel cutoff solenoid will not prevent excess fuel from entering the engine when the needle fails as some falsely say.

 

[mcat2197]

Thanks for your response. I'm concerned about the increased blow by? Could too much fuel actually stop the rings from working and be letting fuel and compression pass the piston? Let me also clarify something..... the oil has fuel in it..... but the oil level was actually on the low end. Wouldn't the carb or the pump letting fuel in raise the oil level?

 

[Scrubcadet10]

It is not unusually for air to be pumping out of the dipstick on a small engine as whenever the piston is moving up and down, that's creating more area in the crankcase and air has to fill that space, and when the piston is traveling back down, it pushes that air out.

 

[mcat2197]

All righty then. I'll be rebuilding the carb first and then the fuel pump if it's not the carb. Two relatively inexpensive fixes. Thanks!

 

[slydog]

Hi All, this is my first thread. I have a 27 hp Kohler cv740. It runs rough and blows some blue smoke at start but then small amount of black smoke.. Plugs are black as could be. There seems to be excessive amount of blow by come out the oil tube. It's getting spark. I checked the needle and seat. Checked the Fuel cutoff solenoid. all seems ok. Someone said it looks like the carb is dumping gas into motor causing wash down of cylinders but would that explain the blow by ????? Is there anything else I should check before I open her up and change the head gaskets?

I see in your question mention of fuel in oil. Sounds like your pulse fuel pump is defective and allowing fuel to enter crankcase. Depending how long the pump is bad you could have considerable breakdown of oil viscosity which would cause the symptoms you've described. The pressure you observed at fill tube will also be present when filler cap is removed. This is normal, and is where the fuel pump gets it's positive and negative pulses to function.

 

[ILENGINE]

@slydog Just for a heads up, The threads that you are answering are old and in the case of this thread almost 2 years old the the OP hasn't logged in since Feb 9, 2021