Craftsman push lawnmower wobble after hitting rocks won't start

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On Fri, 9 Jul 2010 20:39:40 -0400, Stormin Mormon wrote:

I don't understand the "knock off tool". I bought one. But for two reasons, I will return it.
The first reason isn't the tool's fault (it was the wrong size); but even so, how does banging on the crankshaft (and lifting underneath with a pry bar) magically free up the flywheel?
Of course, lifting up on the flywheel with a prybar, is applying force to free it up; but how is whacking the crankshaft applying ANY force whatsoever in the direction we want the flywheel to go (which is up)?
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The knock off tool allows you to move the crank shaft down. Which is the same as moving the flywheel up. Mostly just shears the friction fit from the flywheel to the crankshaft. Try it... worked for many men on many occasions.
--
Christopher A. Young
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On Jul 10, 8:36 am, "Stormin Mormon"
but how is whacking the crankshaft applying ANY force

Pretty much the same way an impact driver works. Also, if you have loosened any bolts/nuts, you know that just pulling on a wrench is much harder than hitting the wrench slightly with your palm is much easier and less busted knuckels. Basically the same principle.
I could explain the physics if needed, but I think you get the point.
Hank <~~~too lazy to write a dissertation
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What Eric said but to explain it a bit more: Lever pressure on the screwdriver and smack the NUT on the crankshaft. That nut needs to be loose with no crankshaft threads showing above it.
I am a member in the church of "a BFH will fix most anything"
Give it a try on your junker.
Harry K
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On Thu, 8 Jul 2010 18:24:09 -0700, "James H."

Did you pry up or down with the screwdriver?

No. What Eric and Harry K said is correct. Growing up, tinkering with mowers I never used (or knew) a puller..
Loosen the nut up to the top of the crank -- do not remove it and make sure the threads are below the nut. Never hit the crank with a hammer, with the nut completely removed. That will cause thread damage and you cannot thread the nut back on.
Position the screwdriver under the flywheel 180° opposite the flywheel key way, pry up with the screwdriver and smack the nut with the hammer. It may pop the first time or need a couple more smacks. Even adding a penetrating oil around the key way/crank will help.

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Sounds like the shear key on the flywheel may have sheared.. This will put the timing off. Also check for damed blade . After this we are talking crankshaft damage... I this is the case it is not worth fixing.
Jimmie
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On Thu, 8 Jul 2010 19:46:57 -0700 (PDT), JIMMIE wrote:

That's exactly what happened. The flywheel "pin" was shaped like a Z (side view) instead of a rectangle (I bought six new Briggs and Stratton flywheel keys from Ace hardware and none look like a Z from the side.)
The hard part wasn't getting the flywheel off; it was figuring HOW to get the flywheel off. Banging on the crankshaft and prying up on the flywheel only served to break the plastic intake manifold in half, bending one of its bolts and breaking the other one in half.
Success only came to me after I totally gave up on this crazy bang-on-the-crankshaft-and-pry-the-flywheel method. When I finally realized there were two untapped holes for a harmonic balancer puller, I simply tapped them with a 1/4 x 20 tap, and voila! The flywheel pulled off with ease using the flywheel puller.
Now I have to order a new plastic intake manifold, and pick up a set of screw extractors to extract the broken intake-manifold bolt.
In hind sight, if you have a Briggs and Stratton engine (specifically the Briggs and Stratton 123K02-0444-E1 engine), DO NOT pry up on the flywheel and bang down on the crankshaft (what's that gonna do anyway, beside break stuff). There's NOWHERE to pry except soft aluminum and plastic anyway.
Just use a harmonic balancer puller (after tapping the holes in the flywheel left for this purpose). I wish I knew that when I started this thread! :)
I do THANK EVERYONE for all your help; it was my first lawnmower repair in my life! When the parts come in for the broken intake manifold, I hope it will work again!
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On Fri, 9 Jul 2010 22:09:17 -0700, James H. wrote:

I ordered a new intake manifold, busted when I followed the errant advice to bang on the crankshaft and pry up on the flywheel.
Don't bang and pry!
Nothing is gonna happen except aluminum and plastic stuff under the engine will break. The plastic part that broke is #50 (intake manifold, Sears PN 497465) and #54 (intake manifold screw) on page 36 of this 40-page pdf. http://www.managemylife.com/mmh/lis_pdf/OWNM/L0505023.pdf http://www.hammerwall.com/Download_Manual/14875 / http://tinyurl.com/32mzm2n
If you ever have to remove a flywheel like the one in my Craftsman 21" push mower 917.388853 with a Briggs and Stratton 6.5HP 123K02-0444-E1 engine, simply tap the two holes in the flywheel with a 1/4 x 20 tap, and use a harmonic balancer puller and voila, the flywheel will come off.
Resist the tempatation to pry (you'll only break stuff) and bang on the crankshaft (what's that gonna do anyway; the crankshaft isn't going to move down?????).
When I pick up a screw extractor set, I'll remove the broken bolt; and when the new intake manifold arrives, we'll put it all back together (with the new crankshaft pin) and cross our fingers.
Thanks for all your advice; you guys are wonderful!
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Worked for me many times, over the years. Sounds like you need a mentor to show you the technique.
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Christopher A. Young
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Only a hammer mechanic uses that method.
Maybe you can patent it and call it the "Budweiser method".
On Sat, 10 Jul 2010 08:37:57 -0400, "Stormin Mormon"

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The method has been in operation so long that tools are made, and speciality items are sold. And the process is reccomended by folks who know.
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Christopher A. Young
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I can do a steering wheel on a car with one hit. A mower flywheel is childs play. Jr.
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On Sun, 11 Jul 2010 02:35:08 -0400, Jerry - OHIO wrote:

In the end, the flywheel was easy to get off once I 1/4x20 tapped the two holes drilled for that purpose but never tapped by the manufacturer and then used a harmonic balancer puller which lifted it right off in seconds.
One thing I just don't understand though.
How is hitting DOWN on the CRANKSHAFT supposed to free the flywheel in the bang-and-lift method?
Can someone explain the logic of banging on the crankshaft to remove the flywheel?
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I'll try (sigh) There is some end play in the crank whether you can feel it or not. The lift with the prybar / screwdriver, takes that up, the hammer blow drives the crankshaft down, while the lift holds the flywheel up causing the crankshaft to move through the flywheel. The hammer blow needs to be quick rather than hard.
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On 7/11/2010 6:01 PM, James H. wrote:

what you do is stick a pry bar UNDER the flywheel, then with the nut started on the crankshaft (to protect the threads) you sharply rap the crank and the flywheel will pop right off. Basically, you are using the (very small) amount of crankshaft end play as your movement. Those holes were not tapped, because that is not what they are for.
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Steve Barker
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http://www.youtube.com/watch?v=Plktb3a_-MI
Around 4.01 he taps it off, he doesn't even bother with the prybar.
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On Sat, 10 Jul 2010 12:08:38 -0700 (PDT), Eric in North TX

Apparently you've never taken a flywheel off.
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Based on what? I've never seen one put up that little fight, but am open to the possibility. Perhaps that Canuk has talent. Tapers are as much VooDoo as skill, I've seen really capable people walk up and drop a tie-rod or ball joint & even a small engine flywheel with a flick of the wrist, that someone else has been slaving over for hours.
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On Sat, 10 Jul 2010 13:11:55 -0700 (PDT), Eric in North TX

IME, it came off easy, because it is a horizontal crank _and_ the shear key was not sheared (you can still see in the crank key way). When the key shears it binds the flywheel and crank shaft. IOW, harder to get off for those without a "puller". It can be done.
Once I popped a flywheel on a vertical shaft: placed a 2 ba fer on the nut and whacked it with a hammer.
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On Sat, 10 Jul 2010 12:08:38 -0700 (PDT), Eric in North TX

At 4:02 he points out that there are no holes for a "puller".
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