Oil clogging the air filter

[Cogitosus]

Hi folks, I'd appreciate some advice

I have a 2-year old Florabest mower, which is a Briggs & Stratton model made for Lidl with the 450e motor. It ran perfectly until last week, when I noticed it was quite smoky on start-up. That cleared when the engine had warmed up, so I assumed that it might have been tilted over by my son to clean the underside of the deck, but it also seemed a little low on power and would stall out more easily than usual.

As I was putting it away, I noticed that oil was dripping from the air cleaner. I opened it up, squeezed out the foam and cleaned it up. The oil was clean and there still seemed to be enough in the sump.

This week it was very reluctant to start. We only got it to run by continually squeezing the primer bulb. It was very smoky and would stall out if we didn't keep pumping. I removed the plug and it seemed to have a thin mixture of oil and fuel on it. Similarly, the air filter element was again contaminated at the bottom of the foam, this time with a mix of fuel and clean oil. I cleaned it out and we eventually got it to start by priming it until it was hot and running smoothly. Once the motor was running smoothly there was no oil smoke, but again it was low on power.

Does this sound like ring failure? I'm all-too-familiar with the signs and sounds of ring failure on a car, but not on a mower. I should add that it's theoretically under warranty, but the odds of my finding the receipt after this time are not good.

All advice appreciated

 

[Rivets]

First thing you need to do is check your oil level. Willing to bet you will find it over full and smells like petrol. If I’m right your carb float needle is not closing properly, allowing fuel to run straight through the carb, into the engine. Repair is to rebuild the carb and changing the oil.

 

[Cogitosus]

Thanks Rivets, that would explain a lot of the symptoms

Soooo... you figure the bowl is overflowing into the sump, raising the oil level until it enters the combustion chamber and simultaneously spills out through the air intake?

That would certainly explain why I'm burning oil and why the spillage all seems to be a fuel-oil mixture. It would also explain why, despite the oil I'm burning, the level on the dipstick is not dropping.

Thank you!

Carb strip-down tomorrow, if the forecast downpour holds off.

 

[bertsmobile1]

EPA regulations outlaw any fuel leaving the engine direct to the atmosphere.
Thus the overflow that you would see and take action about before an ounce or two had dripped out is now inside the carb , usually at the inlet manifold
From there it will dribble inside the manifold and into the cylinder where if you are really lucky it will hydro lock, bend the can rod or blow the head gasket when your try to start the engine.
From the combustion chamber it drips past the rings and fills the sump .
Thus now anything up to 2 gallons of unburned fuel ( depending upon the mower ) will fill up the crankcase , dilute the oil and evntually be removed .
It will overfill your drain container because you were only expecting 2 cups the usually sit in an oil pan where much of the fuel will evaporate off into the air .
Or if the oil goes off for reprocessing will be distilled off & burned in a flare stack thus quadrupeling the amount of pollution.
Isn't it good to have these people looking after our planet ?

 

[Cogitosus]

Fortunately it seems there isn't enough to lock up the cylinder. I suspect that the level of the inlet is such that it can never fill even halfway before flowing out through the intake.

I had planned to drain down the sump through the bung, as I was concerned that I might find ring fragments, but if Rivets is correct - and I think he is - then I can cheat and pump it out through the dipstick hole. I'll update the thread with the results

 

[bertsmobile1]

You have it flowing up hill
It goes in through the intake and out past the piston rings ,
When you crank the engine the oil fuel mix sloshes out of the breather tube.
If you take the breather tube off and crank the engine you will see it spewing out .

 

[tom3]

I'd look for that purchase receipt first. But then a of today's warranties are pretty much garbage unless purchased from an actual lawn mower shop, spend hours on emails and phone calls, lucky to talk to a person, even luckier to get any action.