How to tell if a riding lawn mower engine is seized

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Riding lawn mowers can be super convenient but when they experience technical issues, it’s no laughing matter. Here’s how to tell if the engine has seized on your mower.

What happens when you turn the key?

First, you can try turning the engine key to see if the lawn mower starts. If it doesn’t and instead you hear a grinding or ticking noise, you could have a seized engine to deal with.

Try starting it without the spark plugs

Start by taking out the spark plugs and then trying to start the mower. If the engine starts, then you might need to replace the mower’s valves. However, if the engine doesn’t turn over, then it’s seized.

Check the piston

You can also take a look at the piston to determine if the engine is really seized. Use a flywheel puller to remove the crankshaft and push the piston out to see if it has sustained any damage. A defective or damaged piston usually points to engine troubles.

Try turning the engine pulley

If you reach underneath and try to turn the pulley but it’s stuck or becomes very difficult to turn, then it’s probable that the engine has seized.

Along the same lines, it could be that you disassembled the engine and didn’t put it back together properly. This could lead to issues with the recoil system, which could hurt the mower’s engine. You can try taking off the shroud and trying to turn the engine. If it’s tough to turn, then the engine is seized.

Keep in mind that even small adjustments can make a huge difference in how your riding lawn mower responds and operates. It might not be that the engine is seized but instead the valves or drain plugs are loose. When in doubt, take it to a lawn mower mechanic or repair shop.

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  1. I have a briggs and stratton it turns over fine,put gas in spark plug hole (small amount) grab starter rope,might pull over a couple times then motor ties up.pull spark plug, still won’t pull over,tight as a drum.take head off don’t see a problem motor frees up try again same thing.motor pulls like normal. Do again same result

  2. I have a craftsman riding mower and my wife was mowing … it was working fine. She parked it to eat. She went back out and it would just hum. Gas was leaking like crazy around the carb. I put it in neutral and pushed it in the shade. Got up all the gas and now the rear end is locked. Wheels won’t turn in neutral. Any ideas ?

  3. Not to nit pick, but one of the response on telling if the engine on a riding mower is seized up? I would like to point out that the section on trying to start it without spark plugs. The part where it states with the spark plugs removed you try to start the engine. If it starts then you have a valve issue. I’ve worked on Alfa Romeo cars for years and have yet to find any engine that will start and run without spark plugs. You should probably change that to. If the engine turns over then you might have a valve issue. If it doesn’t turn over then it might be seized. Or the teeth on the flywheel may be stripped off.

  4. my b/s 16hp engine had a pop while mowing,now will not turn over, lock up. pulled spark plug it was destoyed.

  5. Cub cadet 2554, engine just stopped while cutting in low grass, it smoked a little at first, I checked it out seen nothing, put parking brake on, it started up, as soon as I took parking brake off it smoked more and shut off, tryed to start again and I heard starter click and nothing.

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