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Ranwell1, Small Engine Technician
Category: Small Engine
Satisfied Customers: 10304
Experience:  I Own a Lawn Mower Sales and service business (37years). Have 2-cycle and 4-cycle certification.
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I'm looking on a Koehler cv16s that is burning oil (white smoke out of exhau

Customer Question

I'm looking for help on a Koehler cv16s that is burning oil (white smoke out of exhaust), and dumping gas into the crank case (oil smell on dipstick). I've been through several steps: Cleaned Carburetor, Replaced Head Gasket and Crankcase Relief Reed Valve, Replaced Valve Cover, Replaced Carburetor and Fuel Shut Off Solenoid. I also replaced the oil and oil filter before running the engine after each of the above steps. Even after all those steps the symptoms mentioned did not change. The mower will not stall out once the oil starts burning, as it did in the passed. However I shut it down quickly once it did. The oil does not start burning immediately. Instead the mower runs without issue for about 1 minute before the smoking starts. Any suggestions?
Submitted: 2 years ago.
Category: Small Engine
Customer: replied 2 years ago.
I forgot to add that I replaced the fuel filter when I cleaned the carburetor. I also replaced the cap on the gas tank after I noticed the seal was dry rotting. I pulled the tank off and flushed it to get the rubber out of it. I also blew out the gas tank vent line at that time.
Expert:  Ranwell1 replied 2 years ago.
GAs getting into the oil is one of 2 things.1. The float needle valve in the carburetor is bad and needs replaced or the deat is bad and it will need a new carburetor or the float has a hole in it letting gas into the float. Just cleaning the carburetor without using a complete carburetor repair kit will not fix these problems.2. THe fuel pump diaphram is bad and has a hole in it letting fuel past the diaphram into the crankcase. THis would mean you need a new fuel pump.There is also a chance that you have a blown head gasket causing compression to enter the valve chamber and pressurizing the crankcase causing the smoke to happen.In this case you would need to replace the head gasket. You actually can have BOTH of these problems ad one problem can cause the other to appear.LEt me know what you find out.Please give me a good rating as this is the only way that this site pays me for my time.Feel free to contact me further if you need additional information.
Customer: replied 2 years ago.
I used the kit when I cleaned the Carb. Regardless I replaced the entire Carb with a brand new one since cleaning the old one. The new one could still be bad, but unlikely.I already replaced the head gasket, but I will check compression tonight to ensure it is at a proper level. Maybe it blew again through my many tests up to this point.I did forget to mention the mower is gravity fed. There is no fuel pump to cause trouble.Is there any other possible scenario that could cause this issue?Thanks for your time and help.
Expert:  Ranwell1 replied 2 years ago.
NO , that is about all I can think of at this time.
The fuel in the gas has to come from the carburetor somewhere. IT is the only place that fuel comes from since you do not have a fuel pump.
the head gasket can blow if the fuel is in the cylinder,
Make sure that you get the head bolts tight so it won't blow again if you take it off again.
If you take the head off again, you will have to replace the head gasket again. NEVER us a used head gasket.
You could be blowing compression past the valves and into the carburetor and this might be causing the problem.