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Hello Everyone, this is my first post here, I've done some reading around these forums but can't find exactly what happened to me.

So I have a Bolens Self Propelled Mower w/ a Briggs 4.5hp that is probably 12-15 years old my father in law gave to me and I have a Craftsman Push Mower w/ a Briggs 5hp that was purchased 2 summers ago by a friend. He gave me this mower because he moved to a big house and got a riding mower.

1. Bolens mower, I tipped on the side towards the muffler while changing the oil. I believed this to be correct based on videos I had watched on changing mower oil. I completed the oil change and it will now not start. I noticed the carb seemed to become filled with oil and the air filter had oil on it too!

I cleaned the carb on it and replaced the filter and spark plug, but when I try to start it, black oily substance is spitting out of the muffler. It might start for 2-3 seconds then immediately die, even if it doesn't start it's spitting oily blackness from the muffler.

2. Craftsman mower hit a rock on the edge of a garden bed. I didn't know my wife had lined that particular area with rocks and one must have moved out of place and out into the grass. It bent the blade. Again I tipped that mower on it's side towards the muffler and changed the blade...

Now the SAME symptoms are happening to this mower. Spitting black oily substance out of muffler. Did same thing, cleaned carb, changed plug and gas. Issue persists.

Completely confused because i thought it was safe to tip these. I guess it's not and i will go ahead and use sawhorses and put my mowers up on top of these and work under it from here on out, but what should I try to do at this point with these mowers?

I'm more of a computer guy than a motor head but i am under no circumstances afraid to take something apart.

Thanks!

WELCOME to LMF...
When you tip any engine over, always tip so the carb is UP never down.

The oil you have in the muffler will be burned out once you get it running...
When you say you cleaned the carb, did you Remove it and give it a thorough cleaning using carb cleaner? all the passages need cleaned and then blown clear with compressed air.... Oil in the carb is heavy enough that it will block those small passages.

On the mower that hit a rock and bent the blade... that will likely have the same oil plugged carb problem.
PLUS it may also have sheared the flywheel key. You can quickly determine if that's the case... simply spray starting fluid (ether) OR gasoline into the carb, (without air filter installed)... if it fires at all, the key is okay. if not, I would check the flywheel key.

I would also do the spray, or gasoline into the other mower's carb... It may clear enough of the oil blockage to get fuel a passage.. That will save you the tear down and proper cleaning...

Post back with what you find... If you do need to remove, and clean the carbs, I will give you a step by step link to easily do that.. :smile:KennyV

Yes, I took the tank and carb off, cleaned it with carb cleaner, let it dry, and re-assembled it.

It's getting too cold now and I don't really want to buy any more fuel and i've run out and I don't need to mow again that i can tell so I guess I'll just let these mowers sit until next season and hope for the best.

Thanks for your response and the ideas.

As a service center and authorized briggs and stratton dealer let me explain what is going on. The crankcase breather is behind the muffler. When you tip the engine on its side with the muffler down the oil in the crankcase fills the breather and then if you don't allow time for it to drain back into the crankcase it will get drawn into the carb because the breather hose is connected to the carb. the purpose of the crankcase breather is to maintain a vacuum in the crankcase to help keep the oil in the crankcase.

In rare cases people filled the breather and then have it drawn into the carb and into the cylinder above the piston and causing what is call hydraulic lock. Since oil in non compressable it overstressed the rod and broke it.