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Last fall I got a deal on a used Snapper rear-engine rider that was manufactured around 2010. It has a Briggs & Stratton Intek 12.5 HP OHV engine on it. I didn't start it, just brought it home & parked it in the garage for the winter. Now I'm trying to get it in shape for the season, but I can't get it started. I've been troubleshooting & trying diff. things, but no luck so far. My research has led me to believe that the flywheel key may be the problem, so I removed everything necessary to have a look. The key hasn't been sheared off, but it *does* look a little off to me. Just wanted to get some opinions of those more knowledgeable & experienced than a beginner like me. Could this flywheel key be causing (or at least be part of) the problem, or does it look OK? Is it worth going to the trouble to replace it or not?

Looks like its sheared to me. I'm not certain but looks like the key way could be bad in the crank. You need to pull the flywheel and have a better look.

Yes it needs to be replaced.

It looks to me like someone installed a steel keyway and they damage the crankshaft. Remove the flywheel and take a look.

I would say that it needs replaced but I wouldn't say it would cause a non start issue.

pugaltitude said:

I would say that it needs replaced but I wouldn't say it would cause a non start issue.

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Don't agree, very much a non start issue. I find if timing is off by very little on small engines it can be a starting issue. Very simple and cheap repair if all it needs is a key to find out if its a non start issue. Fuel, spark, compression and TIMING and it will run and you know timing is off.

reynoldston said:

Don't agree, very much a non start issue. I find if timing is off by very little on small engines it can be a starting issue. Very simple and cheap repair if all it needs is a key to find out if its a non start issue. Fuel, spark, compression and TIMING and it will run and you know timing is off.

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But I don't think timing is off enough to cause a non start. You get some movement when you tighten the bolt on the flywheel which makes it look as though its sheared. Also its only got a pulley on end of crankshaft so belt would usually break before shearing key but it can happen.

I assume its a model 21,28 with the look of the flywheel so guessing valve, head gasket or carb issue.

It doesn't take very many thousands off on the flywheel key to make a big difference in the timing.

ILENGINE said:

It doesn't take very many thousands off on the flywheel key to make a big difference in the timing.

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Now this I do agree on and think it would be where to start to get this engine running again. Valves and head gasket, check the compression. Carburetor, spray some starting fluid in it and see if it fires. Test for spark and a new spark plug. All cheap and easy things to try.

Thanks for all the replies; I appreciate the input. Tonight I got the flywheel off. The key was not broken, but it *does* look like it was at least stressed significantly, b/c it was gouged on 2 opposite sides. There was also a TON of caked-on dirt packed inside the flywheel & under it all over the coil & the top of the engine that I scraped off, blasted off w/ a can of compressed air, & also vacuumed off. I wonder if all that crud interfered w/ the functioning of the magnets & coil. Tomorrow I'll put everything back together & try to start it again. Fingers crossed.

Progress Report: Put in new flywheel key & put everything back together. Tried to start it w/ the key & just got a click. Pulled rope, & it seemed like I had a compression problem like I had before. Maybe pulling & turning the flywheel threw something off; I don't know. So I adjusted the valves again, then pulled the rope. No start, but the compression problem seemed to be solved. Sprayed some starting fluid into the air intake, pulled again, & it started! ? Only ran for a few secs. before it died, but that's definitely progress. Sprayed some more starting fluid, pulled again, & it started again. Same thing as before, though: only ran for a few secs. So I guess now it's something to do w/ the carb., maybe. Guess I need a new battery, too.

A small bit of advanced timing should not cause an issue with starting, however having run it like that would cause the engine to run hotter than it was supposed to. Good call to replace it. Good luck.

Remember to change the fuel line before you fix everything. You can suck same stuff right back into the carb. Clean the fuel tank as well.

Feeling a little dumb, but had the fuel valve right under the gas tank turned the wrong way. Just started & ran it for about a minute. It does seem unlikely that a flywheel key that was only stressed & not sheared off would keep an engine from starting. Maybe that plus all the crud caked under the flywheel, all over the magnets & coil, were enough together to kill it.

MonkeyCam said:

Feeling a little dumb, but had the fuel valve right under the gas tank turned the wrong way. Just started & ran it for about a minute. It does seem unlikely that a flywheel key that was only stressed & not sheared off would keep an engine from starting. Maybe that plus all the crud caked under the flywheel, all over the magnets & coil, were enough together to kill it.

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Unless they were iron filings it will make no difference, clean , dirty, rusty.
Magnetic flux passes through all of it virtually unaffected.

Correct. We used to run Briggs offset flywheel keys when setting up for racing. Not that were racing here but you get the idea. I've also done away with the key and just loctited the flywheel on to get precise timing. Loctite and let dry.

Matt )