Was it running good the last time?
Did you store it by hanging on the handle so the mower were on the front two wheels?

My first guess is you did not store the mower in level position and the oil creep through the rings and into the combussion chamber.

If the mower was work good last season and this jus happened. I would just run it until the smoke clear.

THis sound just about the same as the Honda 4 cycle trimmer sat in wrong position and smoke. But of cause, if it blow up, I don't know you!!! It's your decision!!!

It should stop after about 10 minutes. Don't worry about it unless it continues for more than that.

If there is signs that the airfilter is contaminated w/oil or that oil is being pumped through the breather hose, that will need to be addressed. Verify that the oil level reads full and not overfull due to fuel entering the engine.

'I tried to start it yesterday, but the engine barely turned over'

The cylinder had oil in it.

'It sputtered quite a big, and grey-blue smoke came out the little vent holes on my left.'

Yes, it was burning the oil and the smoke was coming out of the muffler.

Never tilt the mower up with the carburetor or cylinder head down. Check the oil and adjust the level as needed - do not overfill at all - its better to be a tad under than over. Check the air filter - if its a pleated paper filter, it should not be oily. If oily, replace it. Start mower and use it until it stops smoking - the muffler got oil in it too and it'll take a few minutes to clear out.

Thank you, everyone! I really appreciate the advice.

The mower is stored on the bumpy but level dirt floor of a shed. The only time it's ever tilted is when I lift up the right side to free jammed grass clippings from the discharge. Would that have caused the problem?

I'll try running it again tomorrow if it doesn't rain.

Thanks again!

Susan--

IIRC, Toro Recyclers made from 2002-2007 had Tecumseh engines. If so, then the carburetor is on the left side of the engine, so tilting the mower's right side up would cause oil to enter the carburetor, which could've contributed to your problem. However, I don't know if it also would cause oil to enter the cylinder, which was your main problem.

Hope this helps.

'However, I don't know if it also would cause oil to enter the cylinder, which was your main problem.'

Yes, it could, via the intake valve. I've even seen it happen on larger engines like a 13 HP Honda. Really, on any 4-cycle OPE engine (except the tiny ones that can run in any attitude).

I hope the commercial engines are better!! How do you mow a slanted lawn?

I did not expect oil can get in unless it is sitting for a while!!! Wonder what kind of engineer design this!!!!

Mr. Yungman: IMight i suggest you sit down on a box, and look at a normal, vertical, crank-shaft engine, and then write in and tell us how the oil can get in the cylinder, enough to stop piston movement!
Unless the owner has put too much oil in the crank-case, it will not seep into the cylinder. Not even when sitting & not running!
How do you mow a slanted lawn?
By the time the engine has been running for 60 seconds, the oil will be splashing around in the engine, getting hot and thin, making it into a fog instead of how it comes out of a quart oil can. And that is how the engine gets its lubrication when mowing a slanted lawn! Low oil in the crank-case will cause problems, so it is always advisable to check the oil when starting up the first time.
I have seen photos of lawn mowers hung up by the handle, for storage in a small garage or shed. If the engine is old or worn, this will allow oil to seep past the rings, and fill up the cylinder, causing starting problems later on. Read and heed what saxman said. He's got the right idea as to what caused the problem.

This is getting weird. When a mower is tilted with the carburetor side down at a steep angle, oil can travel back through the breather tube and enter the carburetor. Once in the carb, it can soak the air filter and even make its way into the cylinder via the valves, one of which is usually open. This happens many times a day across the country and has been frequently posted here. When the engine is running, you're not likely to have this happen except on severe slopes that are too steep to be mowing anyway. Oil in the carb will then be indicated by large amounts of oil smoke, which tells you to quit whatever it is you're doing to the mower.

It looks like it's my turn for thick blue smoke. Just got a Lawnboy 2 stroke where the fuel tank emptied into the crankcase. Any hints for the procedure to empty all the fuel out of it?

baymee--

You're kidding, right?

rustyj14, How to lock a mower with oil.
1)Tilt mower with the cylinder down for a long period of time.
2)Oil runs into the cylinder and seeps past the ring end gaps and fill the combustion chamber.
3) Engine on compression stroke with combustion chamber full of oil=locked engine.
This happened to one of my Detroit 6/71s. Engine was way over full of oil and it seeped past the piston rings and filled a combustion chamber. This resulted in a bent rod and cracked cylinder head.

No, not kidding. I know there's no oil in there, but I've never had a Lawnboy apart. Somewhere there's alot of gas mix in there.

Judging by all the grass dust in the tank and on the jet screen inside the bowl, there is no filter in the tank. Most likely, dirt prevented the float from seating the needle.

Removing all the contraptions connected to the carb and trying to get it all back together again reminds me of how much I hate working on these little demons called Lawnboy.

baymee--

Unless this Lawn-Boy has a DuraForce engine (identifiable by the above-deck muffler), the only way I can think of to remove the fuel from the crankcase (other than letting the engine burn it out) is to remove the muffler and let the fuel drain out of the exhaust ports. For a DuraForce engine, you can either remove the exhaust transfer tube to let the fuel drain out of the exhaust port, or you can remove the cylinder head and lift up the back wheels.

The air vane governor on these machines (i.e., "the contraption connected to the carb") does make carb removal an exercise in patience.

Hope this helps.

It was a Dura Forco and I removed the plug and lifted the rear wheels and the gas came out the plug hole. After I was all done, it started right up and purred away.

Sounds good! Now all you need is a replacement fuel tank. (Unfortunately, IIRC, the filter can't be removed by itself on DuraForce fuel tanks---the entire tank has to be replaced.)

Turning the mower on-end is one way to remove gas. Another way is to remove the plug and just pull the starter rope as rapidly as possible several times with the mower on a flat surface. The gas will blow out the spark plug hole. Another way is to use an air hose with a rubber tipped nozzle. Place the nozzle in the spark plug hole with the piston just slightly after top dead center and then pull the trigger on the nozzle. This will spin the engine over rapidly blowing all the gas out the muffler.

I also pulled the starter rope. I know on motorcycle two-strokes, there is place for the gas to collect below the piston if the float fails, but I didn't know physically if there is a place for fuel to collect on a vertical shaft Lawnboy. Everything worked out well and I put an inline mesh filter (Briggs type) in the gas line.