Mower engine won't turn

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Copied text: "After the 2nd pull I realized that my allergies and headache had the better of me and I was not pulling the rope very hard. So I tried again. The rope came out as usual, the engine didn't start, and the rope went back in. So I grapped it again and when I pulled I found that the rope would not come out. Turns out it won't budge."
Sure looks to me like the engine locked up between the second and third pulls. If someone else killed the engine, it woulda been locked up before the first pull, you think?
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Christopher A. Young
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Does it really make much differance in how hard the rope is pulled on the small gas engines ? I have a 5 kw generator and it will take two or 3 pulls to start every time. If I just pull it slow or as hard as I can. Maybe the hard pulls went out when the easy start/low compression came out.
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Ralph Mowery wrote:

With some engines a hard pull works better. Ignition and carburetion may work better with a hard pull.
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With compression release, now days. It's supposed to make it easier to pull the engine. I'm sure it does. Two or three pulls to start, that's about the right number. My seldom used generator, I've had to spray some ether on the paper air filter to get it going. Runs for a few seconds, and then dies. Repeat, until it runs.
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Christopher A. Young
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Agreed.
Remove the engine brake completely Keep spark plug out Carefully check to be sure that there is nothing packed under or around the blade. Clean well around crankshaft. Squirt some penetrating oil at base of crankshaft (where it exits engine block)
Now, Try to turn blade
CY: That's a thought. Locked up where the crank shaft comes out. My best guess is the engine brake isn't really releasing.
Note: Does this mower have a built in generator (for lights or charging battery if it has one)? If there is a generator coil, one winding may have come loose and bound up against flywheel. Check for that if there is a generator. (I had that happen once).
CY: That musta been some years ago. I've not seen generator except on riding mowers. And the OP did say it was pull start.
If it still dont turn, the engine is siezed. Could be the cylinder wall was so dry that just pulling it, caused a piston ring to score the cylinder wall.
CY: He did say the oil was slightly overfull. But that doesn't prevent engine siezing. Especially if the oil hadn't been changed in a long time.
If this happened, flip the engine upsidedown for a few seconds to get crankcase oil into lower part of cylinder. Then when it's upright again, pour some kerosene (or diesel fuel) and motor oil mixed half an half into the cylinder. Leave it sit for a few hours, and try to turn blade again. Use a wooden mallet if needed against the rear (dull side) of the blade, and tap it.
CY: That's a thought. Might be piston siezed.
If none of this works, remove the cylinder head. Take a block of wood like a 8 inch piece of 2x2 or chunk of tree branch. Place wood against top of piston and whack the wood with a hammer. If there is a bit of scoring on the cyl wall, this should free it up. Otherwise you likely have a bent or broken connecting rod, crankshaft, or valve. If thats the case, it's time to tear down the whole engine.
CY: Or, at that point, to pitch in the scrap and go find another mower.
I know a guy who drained the engine oil from a mower in fall, and started it in spring without oil. The piston siezed against the cyl wall. It actually peeled up a small bit of the aluminum cyl wall. He had me look at it. I removed the head and found this. I poured oil all around the piston, let it sit, and whacked the piston with wood block and hammer. It came loose. With the piston all the way down, I used some emery paper and carefully smoothed out the score in the cylinder wall. Then I spun the engine with the blade until it moved freely.
I put on a new head gasket, put the head back on, and it fired right up. However, it did smoke quite a bit from oil leaking past rings at that gouge in the cyl wall. He bought a new mower a few weeks later and gave me that old one. I used that old mower for probably 10 years after. The smoke ceased to be real bad after the rings smoothed out that gouge. I also added some of that STP oil treatment to the oil to help lubricate better.
CY: I'm the same way. I'll spend an hour or two trying to restore an old mower, rather than pitch it and buy a new one.
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Stormin Mormon wrote:

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Is the blade tight?

Have you checked to see if the ignition coil is out of adjustment and jammed against the flywheel?

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I don't think anyone has suggested this yet but please disconect the spark plug before trying to turn the motor with the blade. You will need your fingers for the future. This is not a fix for your problem, but a safety issue.

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Some very good ideas.
LM, thanks for the good post. I'm looking forward to trying this when I get a chance in the next couple days.
There are no lights/battery/generator, so that part is ruled out.

Also, no one else ran the mower since I have. No one but me has access to the power equipment.
I can remove the flywheel brake and see if that helps. I ruled the brake out because it is a pad brake (not a strap brake) and I can see the pad move completely away from the flywheel. If I end up needing to remove the flywheel itself at some point, I'll need to get a flywheel puller and holder. They don't seem to carry those at the local home & garden store.
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That happened to me and when I pulled the sparkplug the tip of it was missing. I followed up by pulling the head and found the tip was wedged between the piston and cylinder wall. Figuring I had nothing to lose at tjis ponit I placed a block of wood against the piston and hit it with a hammer. This drove the piston down just enough for the tip of the sparkplug to free up. I got 4 or 5 more years use out of that engine. I would pull the head and take a look.
Jimmie
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