I don’t think the oil was higher than it was when I changed it, do you think trying to find a genuine carb would be a good idea
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Cub 1440 Backfires and has oil everywhere
- Thread starter Cub1440
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Export threadbertsmobile1
Lawn Royalty
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You do not know anything is right till you check it TODAY
The carb is flooding because the float is not shutting off the fuel as it should.
The bowl has to have an air vent in it or fuel could not flow out and because of EPA laws that vent now is connected to the inlet tract so fuel vapours can not escape into the atmosphere.
The fuel from the defective carb runs down the inlet tract then fill up the cylinder , flows past the rings and dilutes the oil in the sump
The thinner oil does not lubricate the engine properly and bypasses the rings when running so the engine burns oil and smokes .
On top of that the oil level rises from the fuel that has leaked into it and running with the oil level too high will also cause oil to enter the combustion chamber.
And finally the crankcase fume is run back through the carb and if the crankcase oil is thin then that fume will have a lot of oil droplets and of course the fuel so you get even more oil in the cylinder plus the fuel so the "air" entering the carb will have both fuel & oil in it then gets more fuel added to it so it burns rich.
Thus you get oil , black smoke & white smoke all coming out the exhaust , engine misses , has low power output and will surge because the revs will be all over the place.
If there is enough raw fuel in the cylinder when the piston comes up to TDC it can bend the conrod or blow the head gasket
You see now why we are always banging on about buying cheap parts of ebay or amazon .
And the tell tale of an internally blown head gasket is to run the engine for a few minutes.
Turn it off
Count to 10
Take the dip stick out
If smoke rises from the dip stick tube then the gasket is gone
The carb is flooding because the float is not shutting off the fuel as it should.
The bowl has to have an air vent in it or fuel could not flow out and because of EPA laws that vent now is connected to the inlet tract so fuel vapours can not escape into the atmosphere.
The fuel from the defective carb runs down the inlet tract then fill up the cylinder , flows past the rings and dilutes the oil in the sump
The thinner oil does not lubricate the engine properly and bypasses the rings when running so the engine burns oil and smokes .
On top of that the oil level rises from the fuel that has leaked into it and running with the oil level too high will also cause oil to enter the combustion chamber.
And finally the crankcase fume is run back through the carb and if the crankcase oil is thin then that fume will have a lot of oil droplets and of course the fuel so you get even more oil in the cylinder plus the fuel so the "air" entering the carb will have both fuel & oil in it then gets more fuel added to it so it burns rich.
Thus you get oil , black smoke & white smoke all coming out the exhaust , engine misses , has low power output and will surge because the revs will be all over the place.
If there is enough raw fuel in the cylinder when the piston comes up to TDC it can bend the conrod or blow the head gasket
You see now why we are always banging on about buying cheap parts of ebay or amazon .
And the tell tale of an internally blown head gasket is to run the engine for a few minutes.
Turn it off
Count to 10
Take the dip stick out
If smoke rises from the dip stick tube then the gasket is gone
Last edited:
Gord Baker
Well-Known Member
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Drain the Fuel and Carb bowl. Check emulsion Tube holes if you can access them. There is often a very tiny hole on the jet at the bottom of the float bowl. A wire from a wire brush will handle that. Carefully remove Float and needle valve and allow fresh clean gas to wash through the seat area. Carefully reassemble. Do not use an Impact gun on Flywheel bolt.
Really hand tight is good enough. Check tightness on all head bolts and carb mount bolts. Replace Spark plugs with properly gapped and tested ones. If you are confident, check Valve lash. Have new gaskets on hand. Check that coils are wired correctly.
Really hand tight is good enough. Check tightness on all head bolts and carb mount bolts. Replace Spark plugs with properly gapped and tested ones. If you are confident, check Valve lash. Have new gaskets on hand. Check that coils are wired correctly.
sorry for not responding for a while, i ordered a genuine carb and put it on and that didn't solve it. turns out, the coils i had gotten were bad and when i put the original ones back on it ran perfectly.