What was wrong with this mower?

[slomo]

What was the problem?

A log stuck between the deck and the blade. Or the deck was packed up with clippings.

 

[slomo]

I had an issue with a fix that seemed uninituitive enough to me that it might have some value here. Anyone interested in venturing a guess on what was wrong? Let me emphasize that I have fixed the issue, so the thread is more along the lines of entertainment/education vs. helping someone desperate to get something working.

I was cutting very high grass with essentially your basic 21-inch push mower with no self propel. It was powered by a 190 cc B&S L-head engine. While going through the grass, the mower hit a hidden piece of wood and stalled. After that it would not start. There was a bit of an attempt by the mower to run when the recoil was pulled, but it would not stay running no matter how hard I pulled. I took the spark plug out and saw a typical small-engine spark when I held the body of the plug against the head and pulled the recoil. I also did a compression test and measured a respectable 86 PSI reading. I will also mention that the flywheel key was undamaged. What was the problem?

So another he has fuel, compression, air and spark and it doesn't run.

 

[jdtm]

Usually the fly wheel shears the timing key and rotates a few degrees

That would be the first place to look since it probably is the most common problem when a mower hits something it should not, and hopefully the crankshaft does not get bent. I would not have started the thread for a ho-hum problem like that. I had mentioned in the initial post that the flywheel key was OK.

 

[jdtm]

You say you fixed it. Was an external repair, or did you have to get inside the engine to fix it?

The engine internals were all OK. There was no damage to the timing gears, piston, valvetrain, crankshaft, or connecting rod.

 

[jdtm]

A log stuck between the deck and the blade. Or the deck was packed up with clippings.

The recently-sharpened blade tried to split the log for me but did not have enough power behind it to do the job, similar to my experience below, although that was different piece of wood and the mower was OK after I was able to retrieve the blade.

 

[Scrubcadet10]

so you had fuel, spark, and compression. that only leaves spark at the correct time?

 

[PTmowerMech]

Ok, I give. What was it?

 

[jdtm]

Ok, I give. What was it?

I will give the answer tonight (assuming nobody guesses correctly before then) in case anyone else wants to venture a guess or ask diagnostic questions before then.

 

[jdtm]

so you had fuel, spark, and compression. that only leaves spark at the correct time?

HINT: You are drawing more conclusions from the tests I described than they gave.

Regarding ignition timing, there was no internal damage, change in the timing gear alignment, or damage to the flywheel key, so ignition timing did not change after the mower met the log.

 

[scoyote]

was your issue with the blade or the blade adaptor ?