I think I cooked my mower

[Freybird]

11hp Briggs and Stratton in a 38inch cut riding mower.....got it last summer for a song. I have no clue as to the maintenance history.
Spring comes around and thus I change the oil(10w-30 as recommended) and inspect the plug. Fuel tank is almost dry so I fill it up with what I now realize was 93 octane. Starts after a little coaxing but she's about 10 years old so I figure no biggie. Almost complete my acre of lawn and it begins to struggle. I open the throttle some and a slight-rough RPM increase is noticed as it dies. Attempt to restart and I hear the report from the starter engaging but no starter revs. After allowing the motor to cool (the following day)
- I remove the cover to observe the starter and flywheel, OK
- Turn the key and starter again engages but never turns the motor
- Remove spark plug and inspect, OK (never reinstalled the plug)
- Remove the starter and turn key; torque of motor is realized as the motor jumps from my hand, seems good to me!
- Attempts to rotate the flywheel by hand are futile
- Place 15inch pry bar into flywheel's cooling fins and the flywheel does spin full 360degrees with good effort

I suppose I should be glad that this mower has served me well last season and reflect on the old "you get what ya pay for" axiom. But, it'd be really nice to get another season out of it.

Any ideas on what has happened? Could it have been the 93 octane?
Happy Summer and thanks for your input.

[pwd72s]

I doubt the 93 octane had a thing to do with it. I don't know about the 11 horse engine, but the smaller Briggs engines use a "splash" lube system...no oil pump. I suspect your "frozen" engine the result of poor lube, somewhere or other...(edit)...well, poor lube system combined with many hours of use, that is...

[yellowline]

Flathead or OHV?

I worked with Briggs horizontal motors a lot as a kid. The general consensus on them: the only way to kill the old-style ones is to run them out of oil. Maybe it partially seized? I doubt running 93 would kill it, as I ran a tankful of diesel once.

Drain your oil and see how much you get. The large horizontal motors take about 1.5 quarts, I'd think a large vertical shaft engine would be similar.

One other thing: You need proper cooling if it's a flathead. I'd run it at 3/4 or greater throttle whenever you're actively using the tractor.

[fastpat]

Originally posted by Freybird
11hp Briggs and Stratton in a 38inch cut riding mower.....got it last summer for a song. I have no clue as to the maintenance history.
Spring comes around and thus I change the oil(10w-30 as recommended) and inspect the plug. Fuel tank is almost dry so I fill it up with what I now realize was 93 octane. Starts after a little coaxing but she's about 10 years old so I figure no biggie. Almost complete my acre of lawn and it begins to struggle. I open the throttle some and a slight-rough RPM increase is noticed as it dies. Attempt to restart and I hear the report from the starter engaging but no starter revs. After allowing the motor to cool (the following day)
- I remove the cover to observe the starter and flywheel, OK
- Turn the key and starter again engages but never turns the motor
- Remove spark plug and inspect, OK (never reinstalled the plug)
- Remove the starter and turn key; torque of motor is realized as the motor jumps from my hand, seems good to me!
- Attempts to rotate the flywheel by hand are futile
- Place 15inch pry bar into flywheel's cooling fins and the flywheel does spin full 360degrees with good effort

I suppose I should be glad that this mower has served me well last season and reflect on the old "you get what ya pay for" axiom. But, it'd be really nice to get another season out of it.

Any ideas on what has happened? Could it have been the 93 octane?
Happy Summer and thanks for your input.

93 octane runs cooler than 87 octane, so if the engine gave up the ghost, it wasn't octane related.

Go get your self a nice John Deere mower.

[Shuie]

Ah, 'tis the season for weekly Yard Jihad.

I smoked a Lowes Yard Machines with a Briggs & Stratoon in it last year. I knew the motor was going so I just kept on mowing hoping I could finish the yard. It looked like I was spraying for mosquitos when it seized, smoke everywhere. Wife tells me a little later than my Father in law had changed the oil for me the weekend before because I had let it go too long. Motor seized because it had no oil in it. I was really surprised that it ran for a good 15-20 minutes before it puked.

Surpsingly, rebuild kits for the Briggs & Stratton engines are not cheap. I gave the entire mower away to a small engine repair shop and I now pay someone else to cut the grass and to mow over the wife's randomly placed landscaping projects.