What is the typical thing to look for that broke when my lawnmower hit a
> stationary object?
Thanks to all your help, you guys enabled me to figure out what the problem was.
As you all said, it was the flywheel key.
Here are pictures of the job. I learned a lot. What's important to tell others is that the "traditional" brute-force method of removing a flywheel is only for experts and even then, only for people working on other people's mowers! :)
Flywheels are balanced, I have one balanced with a weight on a boat motor, I hope it runs ok because drilling it changed the balance. I had a flywheel on a boat motor that was so tough to remove it took days and ruined - bent, one puller. I can see how it could be hard to remove but it takes practice and maybe a special tool since it had no holes.
I updated the pictures to show the flywheel holes.
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I hope tapping them didn't change the balance as that's all that is required. Do you think merely tapping the two holes changes the balance?
It's the proper way to remove this flywheel (I now know).
Once cleaned (and chalked), you can see in the pictures the Briggs and Stratton flywheel says "TO REMOVE, USE WHEEL PULLER HOLES", and then it has two big arrows pointing to the two untapped holes.
So, the instructions I was given to bang and pry were wrong, at least they're wrong in two ways:
It's definitely not the manufacture's documented method
It's not for someone with zero experience (such as I am).
This video shows the (wrong) traditional method:
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So, I'm posting here to help the next homeowner. The proper way to remove THIS Briggs & Stratton flywheel is:
Tap the two pre-drilled holes (1/4 x 20)
Pull up with a BS 19069 flywheel puller (available as a harmonic balancer puller at any auto parts store)
The owners manual (page 38 & 39) show this as Sears P/N: 19069:
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This is the $7.50 flywheel puller (Briggs & Stratton P/N: BS 19069):
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Briggs & Stratton FAQs say to use the flywheel puller:
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This says it's dangerous (to the equipment) to smack the crankshaft.
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This says the same thing:
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This also says to use the flywheel puller:
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So, I now know the answer but I want the next guy who runs across this advice to get the right advice; otherwise they'll end up breaking more than they repair just as I did by using the wrong method and the wrong tools in the wrong way to remove a Briggs & Stratton flywheel.
While using the brute-force method of removing a flywheel works:
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The proper way to remove this type of Briggs & Stratton flywheel is to tap the holes and use a Briggs & Stratton BS 19069 flywheel puller (also available as a harmonic balancer puller at any auto parts store).
You can see the words saying so right on the flywheel (once cleaned & chalked) in these photos of the job (and destruction) I took:
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The Briggs & Stratton FAQ says to tap the holes with a 1/4 x 20 tap:
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Other articles say to tap the holes and use the flywheel puller:
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This is the $7.50 flywheel puller (Briggs & Stratton P/N: BS 19069):
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The owners manual (page 38 & 39) show this as Sears P/N: 19069:
I have a little conical shape tool which sits on a pointy metal rod, the rod is mounted on a round metal base.The tool is used for checking the balance of lawn mower blades after sharpening them.If a blade is too much out of balance, the blade can cause too much vibration and cause the bottom oil seal to start leaking oil.Those balancer tools are inexpensive.You can buy one at lawn mower shops and some stores such as Lowe's and Home Depot stores.Sears and some hardware stores might have them too. cuhulin
I have an old mower which might have the same problem.
I read some of the references and noticed the ones that compared the two methods always suggested the contraption to pull the flywheel up.
Does anyone know of a reference that actually compares the two methods and still recommends the sharp tap with a hammer over the use of the special tool?
TITLE: Flywheel Removal - The Right Way and Several Wrong Ways QUOTE: "The best technique requires a special tool - a flywheel puller; the least preferred method requires nothing more than a hammer and a screwdriver, but can easily result in serious damage to the flywheel and or crankshaft."
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QUOTE: "There are several approaches to flywheel removal. The best way by far is to use a special puller designed for your particular engine. Briggs & Stratton and Tecumseh flywheels usually have 2 or 3 holes placed around the center of the flywheel which are used with special puller blocks. These have self tapping bolts which you thread into the holes and then tighten down nuts to pop the flywheel off of the crankshaft."
You don't have to take the flywheel off to determine if the key is sheared. Just remove the retaining nut and look at the key. If it isn't sheared no need to take off the flywheel.
Back in the late 1960's or early 1970's my lawnmower hit a brick and sheared the key.I don't remember exactly how I removed the flywheel, but I got it off.That old lawnmower got so old, the fuel tank started vibrating to pieces.One time I tried patching it up with fiberglass. cuhulin
If you can't tell if the flywheel and shaft keyways are aligned, then maybe a visit to the optometrist will help.
I don't even use a key. Just line up the two key slots and tighten the nut. Eliminating the jammed key makes it easier to remove if you hit something, also.
I was thinking about rigging up a lawnmower ''Trick'' Two of my garden hoses connected together with a leak proof plug between the two hoses and my nozzle on one end of the hose.Put a little bit of gas in there.When my lawnmower runs out of gas, I put the nozzle in the tank and turn on the water faucet.But, only gas goes into my lawnmower when I squeeze the nozzle. Make the neighbors think my lawn mower runs on water. cuhulin
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