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Helpful ReplyHot!Flywheel key keeps shearing on Briggs and Stratton 331877-3036-G5 engine

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chief sonny
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2019/03/25 06:39:20 (permalink)
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Flywheel key keeps shearing on Briggs and Stratton 331877-3036-G5 engine

So, the flywheel key keeps shearing on my 21 HP model Briggs and Stratton 331877-3036-G5 engine (on a Craftsman lawn tractor).  I am using a steel OEM key and torque to 110 foot pounds.  I'm at my wits end.  One thing I've noticed is that there is no washer on the bolt assembly, rather the bolt goes through the cover, plastic fin assembly, and then directly into the treads.    Any help would be appreciated.  Also, can someone recommend the best way to hold the flywheel in place during the torquing process?  I've been running a nylon rope in through the spark plug hole but maybe there is a better way?
 
Thanks,
Robert
AVB
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Re: Flywheel key keeps shearing on Briggs and Stratton 331877-3036-G5 engine 2019/03/25 09:33:53 (permalink)
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Running a rope into the cylinder is a good way to bend the valves and/or push rods. What I use is a pry bar with its flat tip (flat blade screw driver style) inserted into teeth of the ring gear and up against the coil mounting post. There are a couple other methods too. One is a modified piston rod for holding the lower crankshaft (PTO end) and another is a pipe wrench on PTO double stack pulley on engine that uses them.
 
There should no plastic between the bolt head and the flywheel. On 330000 models after datecode 120630xxxxxxx Briggs did add a washer under the bolt but this is along with a modified crankshaft and flywheel.
 
You need to read Briggs APSI 82 and 89.
Oliver Douglas
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Re: Flywheel key keeps shearing on Briggs and Stratton 331877-3036-G5 engine 2019/03/30 20:40:14 (permalink)
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The knotted rope method is as old as "L" head engines them selves. I have on hanging on the bench today. We use jute rope. Anything but plastic. Not for use in overhead engines (what you have). Using the coil stand is a dang good way to buy another block. The correct way is with a flywheel tool, sold at your local B&S (Jacks).
Dont tell anyone but we use a battery powered impact driver. We all also have 40 years of doing it this way. (air & plug in b4 batteries).
Get the right tool, for the job done right
AVB
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Re: Flywheel key keeps shearing on Briggs and Stratton 331877-3036-G5 engine 2019/03/31 00:08:54 (permalink)
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Well I have doing this for 10 yrs myself and have yet to break the coil posts. Matter of fact I just torqued a 126L02 flywheel using the method I stated. I would have nor recommend something that I knew would cause damage. Matter of fact Kohler actually recommends using a section of an old starter ring gear place in the flywheel ring teeth and up against the coil's mounting post and alternately the use of a old connecting rod with a heavy washer modified with a flat side to securely mount in the PTO end on the crankshaft key way.
 
Using anything other than a torque wrench to tighten can lead to under and over torqued flywheels. Over torquing flywheels on tapers can cause stuck and crack flywheels. Plus the newer light weight flywheels on the 08P and 09P can literally split in half if over torqued. With a little research on this end I can the picture of one that a DIYer brought in the he split in two and then attempt to pop rivet back together. Under torquing will lead to repeated flywheel key shears and eventually a damaged flywheel key way.
Carl Ellis
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Re: Flywheel key keeps shearing on Briggs and Stratton 331877-3036-G5 engine 2020/01/05 19:34:56 (permalink)
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Yeah, I know this thread is 9 months old, but I just found it.  I'm an old guy with home workshop experience only, so I'm struggling to understand how one
- "runs a nylon rope in through the spark plug hole" to hold the flywheel while torquing the nut, or
- "uses a modified piston rod for holding the lower crankshaft (PTO) end"
How does rope in through the spark hole fasten to anything?  If you tied a nail on it to make a Tee, I could see fishing it through the spark hole and then letting the nail hold against the head, but how easy would that be to fish the nail out?
And I just can't picture a rod holding the crank.  How's that work?
Roy
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Re: Flywheel key keeps shearing on Briggs and Stratton 331877-3036-G5 engine 2020/01/05 21:00:16 (permalink) ☄ Helpfulby Carl Ellis 2020/01/05 21:31:19
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Tie an overhand knot in the rope and feed it into th hole. Now rotate the crankshaft until the piston stops against the knot. Using a connecting rod without the cap bolt a flat washer to the mating surface, it will catch the pto keyway.
AVB
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Re: Flywheel key keeps shearing on Briggs and Stratton 331877-3036-G5 engine 2020/01/06 13:39:56 (permalink)
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Don't put anything metal the cylinder area, just the rope. Just note that with this being an OHV engine valve damage can occur even with the rope if open is open at the time piston reaches the top of the stroke with the rope in place.
 
As the rod tool for holding the crankshaft here is an image of how one is setup.

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