Craftsman push lawnmower wobble after hitting rocks won't start

[James H.]

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! :)

See details here: Direct Link:

Link: Player:

[ransley]

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.

[m6onz5a]

[m6onz5a]

First check for a bent blade. If you replace the blade & it still shakes/wobbles you bent the crank.

[mkirsch1]

No.

What's important is to tell others that engine work is too complicated for morons who didn't pay attention in 7th grade physical science class.

[James H.]

Hi Ransley,

I updated the pictures to show the flywheel holes.

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:

1. It's definitely not the manufacture's documented method
2. It's not for someone with zero experience (such as I am).

This video shows the (wrong) traditional method:

So, I'm posting here to help the next homeowner. The proper way to remove THIS Briggs & Stratton flywheel is:

1. Tap the two pre-drilled holes (1/4 x 20)
2. 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:

This is the $7.50 flywheel puller (Briggs & Stratton P/N: BS 19069): Briggs & Stratton FAQs say to use the flywheel puller: This says it's dangerous (to the equipment) to smack the crankshaft. This says the same thing: This also says to use the flywheel puller: 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.

Thansk everyone! I hope this helps others.

[James H.]

Thanks for that advice. I don't see a wobble in the blade but I did order a new blade and I'll report back whether or not the crankshaft is bent.

I'll measure the distance from the blade to the ground in the East-West position and then in the North-South position.

If it's off, I'll buy a new crankshaft and put it in if I can. That would be a whole new set of pictures! :)

[James H.]

While using the brute-force method of removing a flywheel works:

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:

The Briggs & Stratton FAQ says to tap the holes with a 1/4 x 20 tap: Other articles say to tap the holes and use the flywheel puller: This is the $7.50 flywheel puller (Briggs & Stratton P/N: BS 19069): The owners manual (page 38 & 39) show this as Sears P/N: 19069: Net result:

1. Do not pry and bang
2. You must tap and pull

[Oren]

Caution: Replacing the crankshaft may require the judicial use of a pry bar and a hammer. You have been warned.

If you bent the crank, go buy a new mower for 200 bucks.

[Bob F]

That would be "you", not me.

[Brent]

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."

TITLE:

"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."

[Brent]

Ops. I forgot to list the reference for the first quote comparing the methods and concluding the special tool was the preferred method.

The second quote came from here. Both compared the two methods and concluded the special tool was safer.

Do you know of any reference that compares both methods yet still recommends the hammer and screwdriver method over the puller method?

[Oren]

Golly gee. We all know the hammer is last resort. Some flywheels don't have holes for a puller. Using the wrong "special tool" as the OP -- you can fracture the flywheel. He bent his flywheel... he saw it "bend".

Tradition, I say!

My best reference was my grandfather. I was knee-high to a grass hopper. Off the frame, he picked the engine up by the flywheel (nut positioned at the top). Not far from the ground he smacked the crank... remove nut and go to work.

Sorry I didn't keep a journal

[jim]

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.

-jim

[Oren]

No but looking at the shear key under the nut will not tell you if the key fractured midway in the crank key way.

Some keys don't snap or look obvious. The engine will misfire.

[Harry K]

Yep, BTDT and have the t-shirt. Took me a full day fooling with it before I finally pulled the flywheel and saw the half-sheared key.

Harry K

[jim]

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.

-jim