Loctite 620 (green) for example...not blue or red that are for threaded fasteners. Must use a product for bonding cylindrical pieces. Follow Loctite requirements for cleaning surfaces before applying and also curing time... typically 24 hours at ambient temperature.
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Briggs & Stratton 31C707 won’t start after flywheel magnet failure
- Thread starter Lixsán
- Start date
Is this the one?
Red Max 504793001 FLYWHEEL 698281 - Jacks Small Engines
https://share.google/U65675KhXte2C8qNZ
Red Max 504793001 FLYWHEEL 698281 - Jacks Small Engines
https://share.google/U65675KhXte2C8qNZ
If you can't return the new flywheel it can still be used by installing it without the key. Many on here will tell you you can't do that but they are simply wrong. I have installed dozens or flywheels on Briggs racing engines without keys, some that turn as high as 9500 RPMs, without failure. The flywheel is held in place by the taper, the key is there only to help you position it correctly. First install the old flywheel with the key in place You need not torque the nut to spec, just enough to hold it in position. Rotate the crank and align the edge of the magnet with the edge of one of the coil legs. If you have a way to hold the crank in position by all means do that, it is important to not have the crank move when torquing the nut. Remove the old flywheel and install the old one without the key. Orient the flywheel magnet to coil leg exactly the way you did with the old flywheel. Make sure you use a washer between the flywheel and the nut, a little bit of lube on both sides of the washer. Tighten the nut to spec with a torque wrench. You may be tempted to put some Loctite on the crank taper, DON'T (especially green!) if you ever want to get it off again.
Last edited:
farmerdave1954
Active Member
Wouldn't the missing flywheel key be just as much of an out-of-balance issue as the removed material from cutting an additional keyway?C
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 !
andrewslarge
Well-Known Member
No. I too have seen racing engines without a flywheel key and they used valve lapping paste to hold it to advance or ****** the timing.Wouldn't the missing flywheel key be just as much of an out-of-balance issue as the removed material from cutting an additional keyway?
Read post #43
The key is only for timing.
Make sure the crank taper and the flywheel taper are degreased.
Torque to specs and go mow.
This will also let you know immediately if the engine has other issues.
Them 31 series Briggs engines are wimpy made (Briggs should be ashamed of themselves) and about time you put some money and time into one it fails big time, so be aware and don't be surprised.
The key is only for timing.
Make sure the crank taper and the flywheel taper are degreased.
Torque to specs and go mow.
This will also let you know immediately if the engine has other issues.
Them 31 series Briggs engines are wimpy made (Briggs should be ashamed of themselves) and about time you put some money and time into one it fails big time, so be aware and don't be surprised.
Last edited:
farmerdave1954
Active Member
What I meant was that cutting a new keyway and filling it with a keyway, and abandoning the original keyway would not result in imbalance than abandoning the original keyway and leaving it empty. Maybe I misunderstood the comment. But, in any event I don't believe the amount of material removed for a new keyway, especially that close to the center of rotation would cause a significant balance. WIth no key at all, there's still going to be an empty keyway. It's one of those comments that I probably should have left unsaid.No. I too have seen racing engines without a flywheel key and they used valve lapping paste to hold it to advance or ****** the timing.
andrewslarge
Well-Known Member
I understand what you meant and you are correct. It’s possible to get this engine running now.
Personally, I’d find a good used flywheel that is correct for this engine that matches the correct keyway and call it a day. I’ve seen them available for as low as $60 and as high as $160 delivered. That is a bit cheaper than a replacement engine?
Personally, I’d find a good used flywheel that is correct for this engine that matches the correct keyway and call it a day. I’ve seen them available for as low as $60 and as high as $160 delivered. That is a bit cheaper than a replacement engine?