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Hello All,
I came here hoping for some help. I have a Murray riding mower with an 11hp briggs engine that will not turn over. Not sure if it is seized. I bought it from a friend of my father in law back in September when we bought our house. It ran fine when we got it and I used it for a few hours one day trying to get used to it (never mowed a lawn before, never rode a mower, and wasnt sure how to navigate the hills, levels, and rocks in my yard). It was running fine and then I shut it off to refuel. When I went to start it, it let out some black smoke and died. I haven't been able to get it to run since. There is plenty of oil. (Edit: Is it possible that with out an oil pump the oil wasnt being circulated when I was on the hills and uneven parts of the yard?)

I shot some video of the no-start condition in the hopes that someone can help me diagnose and possibly repair. At this point, I do not want to buy a new engine for it as I am already $350 into it. Any more and I can just buy a new self propelled. It wont be as fun to use but will do the job for my yard. Video here: https://youtu.be/7T56P7QNNVQ.

Thank you all in advance!

Chris

I would say first remove the drive belts and isolate the engine or drive. If its the engine remove the head and see if anything is on top of the piston.

Thanks so much. Not to sound naive, but then drive belts would simply be the belt underneath that attaches to both the deck and the...transaxle(?), correct?

reynoldston said:

I would say first remove the drive belts and isolate the engine or drive. If its the engine remove the head and see if anything is on top of the piston.

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Should have 2 belts. Lower one drives the deck(deck belt). Upper one drives the rear end(drive belt).

I would take out plug and try turning by hand. Was black smoke from exhaust?

For starters , try to turn the engine over by hand by pushing down on the screen & turning your hand.
If it won't move. Remove the spark plug and try again.

If it turns around 2 full turns they it is not seized and if it does not make crunching or grinding noises then nothing major is likely to be broken.
It should make some wheezing type sounds as the gasses are sucked in & blown out.
Stamped into the cover near the spark plug should be some numbers, If you can find them and post them it will make things a lot easier.

Was there a big bang with the cloud of black smoke ?

Ok, Pulled plug , removed starter cover, and removed the mesh cover over the fly wheel (side note, did not realized that when I unbolted the oil fill neck, that it was basically held in place by that one bolt and that the slightest movement would unseat it and allow oil to leak out....). I can turn it by hand with force counter clockwise (standing in front of the mower and looking down). But not at all clockwise. Starter teeth are all good as well as teeth on the fly wheel that meet the starter.

What next should I try?

bertsmobile1 said:

For starters , try to turn the engine over by hand by pushing down on the screen & turning your hand.
If it won't move. Remove the spark plug and try again.

If it turns around 2 full turns they it is not seized and if it does not make crunching or grinding noises then nothing major is likely to be broken.
It should make some wheezing type sounds as the gasses are sucked in & blown out.
Stamped into the cover near the spark plug should be some numbers, If you can find them and post them it will make things a lot easier.

Was there a big bang with the cloud of black smoke ?

Click to expand...

Yes it was. This is from a previous reply: Ok, Pulled plug , removed starter cover, and removed the mesh cover over the fly wheel (side note, did not realized that when I unbolted the oil fill neck, that it was basically held in place by that one bolt and that the slightest movement would unseat it and allow oil to leak out....). I can turn it by hand with force counter clockwise (standing in front of the mower and looking down). But not at all clockwise. Starter teeth are all good as well as teeth on the fly wheel that meet the starter.

What next should I try?

Mikel1 said:

I would take out plug and try turning by hand. Was black smoke from exhaust?

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Going to have to dive deeper.

If oil comes out of the filler neck then there was too much in the crank case.
Oil level should be just below the hole in the crankcase once the rubber grommet that seals off the dip stick tube is removed.

Now you say the engine rotated counter clockwise but not clockwise ?
Or the starter motor rotates one way & not the other.

If the starter is not jambed into the flywheel the motor should turn in either direction with roughly the same effort.

The oil is mixed with gasoline I removed the filler neck completely and about half a gallon of oil/gas mixture came out.
The engine didn't rotate fully counter clockwise, just about 1 turn then stopped. Starter motor appears to be fine.

Thanks

bertsmobile1 said:

If oil comes out of the filler neck then there was too much in the crank case.
Oil level should be just below the hole in the crankcase once the rubber grommet that seals off the dip stick tube is removed.

Now you say the engine rotated counter clockwise but not clockwise ?
Or the starter motor rotates one way & not the other.

If the starter is not jambed into the flywheel the motor should turn in either direction with roughly the same effort.

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Well that is very sad news for your engine.
As the Queen of Hearts said to Alice
"OFF WITH YOU"

Me thinks you will find a bent / broken rod

So today I drained the oil. I cannot turn the flywheel by hand now. I took off the cylinder head because, hey, what have I got to lose at this point? Might as well try and learn. Smaller valve is stuck out and cannot be pushed in. Bigger valve is flush with block and will not move either. Piston was able to be pushed back with minimal effort.

I'm sure this is shot at this point.

bertsmobile1 said:

Well that is very sad news for your engine.
As the Queen of Hearts said to Alice
"OFF WITH YOU"

Me thinks you will find a bent / broken rod

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Well the stuck valve will prevent the engine from being turned over.
The engine may be economically recovered.
It will all come down to the state of the crank and the bore,
So flip it over and pull the sump