B&S 17.5 HP

[hank5459]

The tractor would not start, so I checked the fuel line. It was clogged but got it cleared out. The tractor started and I got 1/2 the yard done. Then it quit while in idle and when it quit blew out a bit of blue smoke. I checked the oil and although it was a little low, not out. I put a little oil in and tried to start it. The engine turned but did not turn over. Sounds like it's getting spark, has oil and gas and gas line is flowing fine. I let it set for about half hour. Now it will not turn at all but the starter is working. Once in a while it will turn a few times and then stop with a thud. I let it set a few hours. Now it's not turning at all as if the engine is 'locked up.'

 

[ILENGINE]

Carb needle valve leaking causing it to fill the cylinder with gas, and hydrolocking the piston. Remove the spark plug and see if gas runs out.

 

[hank5459]

That makes sense because it acted like it was flooded. Thanx.

 

[bertsmobile1]

Try to riotate the engine with the plug removed as the "thud" could also be a rock or twig stuck inside the flywheel.
If this is the case it will stop with a thud at almost the same place in both directions