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Briggs & Stratton 31C707 won’t start after flywheel magnet failure
- Thread starter Lixsán
- Start date
Look at the casting numbers ....original is -200 or -700 hard to tell, the new one is -100.How do you know you have the “correct” replacement flywheel?
It seems your trouble shooting skills are excellent and IF everything is correct it SHOULD run perfectly.
I’m thinking the flywheel is incorrect. It could be the magnets are oriented differently North South instead of South North. It could be the keyway is different. If you have the old flywheel you might be able to find out
Others have given you guidance on the big 3: fuel, compression, and spark at the correct time. I think you have an issue with the latter.
Please let us know your findings?
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Magnet orientation N-S makes zero difference....all that is required is a flux in the coils from the passing magnetic field.How do you know you have the “correct” replacement flywheel?
It seems your trouble shooting skills are excellent and IF everything is correct it SHOULD run perfectly.
I’m thinking the flywheel is incorrect. It could be the magnets are oriented differently North South instead of South North. It could be the keyway is different. If you have the old flywheel you might be able to find out
Others have given you guidance on the big 3: fuel, compression, and spark at the correct time. I think you have an issue with the latter.
Please let us know your findings?
Last edited:
Yes...even when they're broken. The keyway alignment and the spark timing magnet on the outside will always be correct if in the same alignment. The alternator magnets are on the inside. You can rip ALL the alternator magnets out and still know which is the correct flywheel.not when they are broken
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698281 Superseded to 7049776YP view new partI saw that one and a couple like it but the top is completely different than 698281. All the sold ones labeled 698281 have the same top as his. I am concerned that it may be for a different engine.
698281 is No Longer Available
No.Cutting a new keyway seems best. Be sure to use the Aluminum Keys, not steel.
Stevie Wonder and Ray Charles approve.....Ronnie Milsap can see those flywheels are not the same.
CHi everyone,
I’m looking for some advice on a Briggs & Stratton 31C707 Type 3346 G5 engine.
The problem started when the flywheel magnets came loose and struck the stator while I was cranking the engine with the starter motor, causing the engine to lock up.
Since then I have:
- Installed a new flywheel.
- Installed a new stator (alternator).
- Installed a new flywheel key.
- Verified strong blue spark.
- Confirmed the spark plug gets wet with fuel after cranking.
- Confirmed the engine has compression.
- Verified the valves are moving normally.
- Found an air leak at the crankcase breather cover because the cover was warped. I flattened the cover on glass, cleaned both mating surfaces thoroughly, and resealed it with Permatex Black RTV. I’m currently waiting for the sealant to cure before testing again.
The engine still cranks but will not fire or even attempt to start.
My question is: Could something inside the engine have been damaged when the flywheel magnets came loose and the engine locked up during cranking? What would you check next?
Briggs & Stratton, 31C707, no start, flywheel
Could the ignition timing still be incorrect even with a new flywheel and flywheel key?
Any advice would be greatly appreciated. Thank you!
698281 is correct flywheel used before code 12071800. Options are to find used one. New old stock from somewhere in the World. Replace engine with new for about $1000...such as 33s877-0019-g1. That engine is for a tractor with manual engagement mower deck...9 amp stator. As far as having the 591749 keyway cut to another location...that can be done...BUT, the flywheel must be balanced. A out of norm fix could be to fit the 591759 to your engine without a flywheel key. The crank end should have a slight taper, as should the flywheel. As much as lapping valves with lapping compound, you could lap the flywheel to the crank... basically you are ever so slightly roughing the surface for more of a friction fit to work with the tight taper fit. Use the original flywheel for alignment. The keyway on the 591759 won't be close to the crank keyway. Remember you are eliminating the key. Try it dry, it will start if you get it aligned exactly. Once you have it to that point, mark it's position with the crank, remove and use Loctite stud & bearing mount to "glue" the flywheel and crank together. This is a high strength adhesive that will require a puller & 500 degrees of heat to disassemble. Install nut and torque to 110 foot pounds. Another option would be to skip the Loctite and just torque the nut...it might stay in position forever or need to be redone in the future. Good luck !Hi everyone,
I’m looking for some advice on a Briggs & Stratton 31C707 Type 3346 G5 engine.
The problem started when the flywheel magnets came loose and struck the stator while I was cranking the engine with the starter motor, causing the engine to lock up.
Since then I have:
- Installed a new flywheel.
- Installed a new stator (alternator).
- Installed a new flywheel key.
- Verified strong blue spark.
- Confirmed the spark plug gets wet with fuel after cranking.
- Confirmed the engine has compression.
- Verified the valves are moving normally.
- Found an air leak at the crankcase breather cover because the cover was warped. I flattened the cover on glass, cleaned both mating surfaces thoroughly, and resealed it with Permatex Black RTV. I’m currently waiting for the sealant to cure before testing again.
The engine still cranks but will not fire or even attempt to start.
My question is: Could something inside the engine have been damaged when the flywheel magnets came loose and the engine locked up during cranking? What would you check next?
Briggs & Stratton, 31C707, no start, flywheel
Could the ignition timing still be incorrect even with a new flywheel and flywheel key?
Any advice would be greatly appreciated. Thank you!
Flywheel has to be in balance. Cutting a new keyway throws off that balance.
Cutting a new keyway throws it off balance.yes. The timing is off with the new flywheel. Not just off but way off.
The simplest solution until you can find one, and there are none on ebay that I could find. New is NLA and no one is posting a superceded number. You can pull the rest of the magnets off, use a rotary sander to remove the epoxy that held them on, and run it without charging. The other alternative until you can find a replacement is to take both to a machine shop, have them measure and weigh the two to be sure they are similar in size and weight, then have a new key way cut in the right location. Neither may be optimal and frankly, all bets are off as to whether a new keyway would eventually cause a crack on the old key way, or the new one. Finding a shop that can cut a key may be hard, and even then getting the timing right may not work.
A mower bone yard may have one. There is one on ebay but it is probably as much $$ as a new one.
Hi everyone,
I’m looking for some advice on a Briggs & Stratton 31C707 Type 3346 G5 engine.
The problem started when the flywheel magnets came loose and struck the stator while I was cranking the engine with the starter motor, causing the engine to lock up.
Since then I have:
- Installed a new flywheel.
- Installed a new stator (alternator).
- Installed a new flywheel key.
- Verified strong blue spark.
- Confirmed the spark plug gets wet with fuel after cranking.
- Confirmed the engine has compression.
- Verified the valves are moving normally.
- Found an air leak at the crankcase breather cover because the cover was warped. I flattened the cover on glass, cleaned both mating surfaces thoroughly, and resealed it with Permatex Black RTV. I’m currently waiting for the sealant to cure before testing again.
The engine still cranks but will not fire or even attempt to start.
My question is: Could something inside the engine have been damaged when the flywheel magnets came loose and the engine locked up during cranking? What would you check next?
Briggs & Stratton, 31C707, no start, flywheel
Could the ignition timing still be incorrect even with a new flywheel and flywheel key?
Any advice would be greatly appreciated. Thank you!