I've got a Toro mower (Model 20016) with a 4 cycle Tecumseh engine
that is trying to hurt me.

When I try to start it, the start cable will pull out about half-way,
under normal starting tension, and then it feels like the compression
of the engine trys to yank it back in. It will violently pull my arm
back towards the mower.

When it eventually does start, there are 3 - 4 loud knocks (*not*
backfires) and then the mower runs fairly normally. I say "fairly
normally" because it no longer runs as smooth and quiet as it used
too.

The mower is at least 4 years old. Should I be looking at the fall
sales flyers?

"DerbyDad03" wrote in message
oups.com...
I've got a Toro mower (Model 20016) with a 4 cycle Tecumseh engine
that is trying to hurt me.

When I try to start it, the start cable will pull out about half-way,
under normal starting tension, and then it feels like the compression
of the engine trys to yank it back in. It will violently pull my arm
back towards the mower.

When it eventually does start, there are 3 - 4 loud knocks (*not*
backfires) and then the mower runs fairly normally. I say "fairly
normally" because it no longer runs as smooth and quiet as it used
too.

The mower is at least 4 years old. Should I be looking at the fall
sales flyers?

Either the blade is loose, or the flywheel key is sheared, causing the timing to
be off.

Bob

On Sep 15, 11:32 am, "Bob F" wrote:
"DerbyDad03" wrote in message

oups.com...

I've got a Toro mower (Model 20016) with a 4 cycle Tecumseh engine
that is trying to hurt me.

When I try to start it, the start cable will pull out about half-way,
under normal starting tension, and then it feels like the compression
of the engine trys to yank it back in. It will violently pull my arm
back towards the mower.

When it eventually does start, there are 3 - 4 loud knocks (*not*
backfires) and then the mower runs fairly normally. I say "fairly
normally" because it no longer runs as smooth and quiet as it used
too.

The mower is at least 4 years old. Should I be looking at the fall
sales flyers?

Either the blade is loose, or the flywheel key is sheared, causing the timing to
be off.

Bob

Blade is tight...one of the first things I checked.

DerbyDad03 wrote:
On Sep 15, 11:32 am, "Bob F" wrote:

"DerbyDad03" wrote in message

groups.com...


I've got a Toro mower (Model 20016) with a 4 cycle Tecumseh engine
that is trying to hurt me.

When I try to start it, the start cable will pull out about half-way,
under normal starting tension, and then it feels like the compression
of the engine trys to yank it back in. It will violently pull my arm
back towards the mower.

When it eventually does start, there are 3 - 4 loud knocks (*not*
backfires) and then the mower runs fairly normally. I say "fairly
normally" because it no longer runs as smooth and quiet as it used
too.

The mower is at least 4 years old. Should I be looking at the fall
sales flyers?

Either the blade is loose, or the flywheel key is sheared, causing the timing to
be off.

Bob


Blade is tight...one of the first things I checked.

Then, as the prvious poster indicated, the blade may have struck
something solid, stopping the engine shaft suddendly, and the inertial
energy in the flywheel made it want to keep turning so the flywheel key
sheared. Now the flywheel is a little "forward" of where it needs to be,
causing the spark to occur too soon.

Pull the engine cover and the flywheel and if you find the key fully or
partially sheared, replace it. The key itself costs next to nothing.

HTH,

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.98*10^14 fathoms per fortnight.

On 15 Sep, 14:05, Jeff Wisnia wrote:
DerbyDad03 wrote:
On Sep 15, 11:32 am, "Bob F" wrote:

"DerbyDad03" wrote in message

groups.com...

I've got a Toro mower (Model 20016) with a 4 cycle Tecumseh engine
that is trying to hurt me.

When I try to start it, the start cable will pull out about half-way,
under normal starting tension, and then it feels like the compression
of the engine trys to yank it back in. It will violently pull my arm
back towards the mower.

When it eventually does start, there are 3 - 4 loud knocks (*not*
backfires) and then the mower runs fairly normally. I say "fairly
normally" because it no longer runs as smooth and quiet as it used
too.

The mower is at least 4 years old. Should I be looking at the fall
sales flyers?

Either the blade is loose, or the flywheel key is sheared, causing the timing to
be off.

Bob

Blade is tight...one of the first things I checked.

Then, as the prvious poster indicated, the blade may have struck
something solid, stopping the engine shaft suddendly, and the inertial
energy in the flywheel made it want to keep turning so the flywheel key
sheared. Now the flywheel is a little "forward" of where it needs to be,
causing the spark to occur too soon.

Pull the engine cover and the flywheel and if you find the key fully or
partially sheared, replace it. The key itself costs next to nothing.

HTH,

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.98*10^14 fathoms per fortnight.- Hide quoted text -

- Show quoted text -

Thanks!

Will I be able to/have to move the flywheel back to where it should
be? Will it be obvious how to do that once I pull the cover?

"DerbyDad03" wrote in message
oups.com...

Thanks!

Will I be able to/have to move the flywheel back to where it should
be? Will it be obvious how to do that once I pull the cover?


It will be obvious. In fact you may be able to tell if the key is partially
sheared without even removing the flywheel. just look at the shaft/flywheel
contact area. If there's a square aluminum 'key' there and it's still
square, it's not the problem. But, most likely you'll have to remove the
flywheel to find out for sure.

On Sat, 15 Sep 2007 14:01:28 -0600, "Bob M." wrote:


"DerbyDad03" wrote in message
roups.com...

Thanks!

Will I be able to/have to move the flywheel back to where it should
be? Will it be obvious how to do that once I pull the cover?


It will be obvious. In fact you may be able to tell if the key is partially
sheared without even removing the flywheel. just look at the shaft/flywheel
contact area. If there's a square aluminum 'key' there and it's still
square, it's not the problem. But, most likely you'll have to remove the
flywheel to find out for sure.

I don't recall seeing the key being obvious; until I removed the
retaining nut from the flywheel.

You can test for movement in the flywheel (FW). Remove the plug wire
for safety. With some help, hold the blade steady and rotate the FW to
observe for any movement back and forth. It is not totally accurate,
but a seriously damaged shear key will be obvious. YMMV.

Small fractures in the key will not be obvious, as well!

About the hammering on the shaft. I use a block of wood to deaden the
blow AND I always leave the loosened nut on the shaft. It prevents
damaged to the thread.

--
Oren

"I don't have anything against work. I just figure, why deprive somebody who really loves it."

On Sat, 15 Sep 2007 15:34:19 -0400, Meat Plow
wrote:

The key ensures the
proper position of the flywheel so there is no guesswork.

They can be a booger now and then; when placing the FW on. The key
might slip a tad. I use a tiny bit a grease to help hold the key in
the crank slot - if I ever have to do it again.


--
Oren

"Well, it doesn't happen all the time, but when it happens, it happens constantly."

It does sound like the timing has advanced. And the only way for that to
happen is for the key in the flywheel to shear and the flywheel slip on the
crank. I'd check that first.

s

OR you have some really **** poor gas. G


"DerbyDad03" wrote in message
oups.com...
I've got a Toro mower (Model 20016) with a 4 cycle Tecumseh engine
that is trying to hurt me.

When I try to start it, the start cable will pull out about half-way,
under normal starting tension, and then it feels like the compression
of the engine trys to yank it back in. It will violently pull my arm
back towards the mower.

When it eventually does start, there are 3 - 4 loud knocks (*not*
backfires) and then the mower runs fairly normally. I say "fairly
normally" because it no longer runs as smooth and quiet as it used
too.

The mower is at least 4 years old. Should I be looking at the fall
sales flyers?

On Sep 15, 6:10 pm, Oren wrote:
On Sat, 15 Sep 2007 15:34:19 -0400, Meat Plow
wrote:

The key ensures the
proper position of the flywheel so there is no guesswork.

They can be a booger now and then; when placing the FW on. The key
might slip a tad. I use a tiny bit a grease to help hold the key in
the crank slot - if I ever have to do it again.

--
Oren

"Well, it doesn't happen all the time, but when it happens, it happens constantly."

Assuming the FW key is the problem, how bad is it for the mower to run
like this? It's September in Upstate NY, so I only have a few more
mows before I'd be putting it up for the winter anyway. I'd just as
soon wait until the season's over before my first foray into small
engine repair.

If the timing is advanced too far, it will burn a hole in the piston or
detonate it self to death.

steve


"DerbyDad03" wrote in message
ps.com...
Assuming the FW key is the problem, how bad is it for the mower to run
like this? It's September in Upstate NY, so I only have a few more
mows before I'd be putting it up for the winter anyway. I'd just as
soon wait until the season's over before my first foray into small
engine repair.

On Sep 15, 8:01 pm, "Steve Barker LT"
wrote:
If the timing is advanced too far, it will burn a hole in the piston or
detonate it self to death.

steve

"DerbyDad03" wrote in message

ps.com...



Assuming the FW key is the problem, how bad is it for the mower to run
like this? It's September in Upstate NY, so I only have a few more
mows before I'd be putting it up for the winter anyway. I'd just as
soon wait until the season's over before my first foray into small
engine repair.- Hide quoted text -

- Show quoted text -

- If the timing is advanced too far, it will burn a hole in the piston
or detonate it self to death.

THEN do I get to buy a new one? ;-)

"DerbyDad03" wrote in message
ups.com...
On Sep 15, 8:01 pm, "Steve Barker LT"
wrote:
If the timing is advanced too far, it will burn a hole in the piston or
detonate it self to death.

steve

"DerbyDad03" wrote in message

ps.com...



Assuming the FW key is the problem, how bad is it for the mower to run
like this? It's September in Upstate NY, so I only have a few more
mows before I'd be putting it up for the winter anyway. I'd just as
soon wait until the season's over before my first foray into small
engine repair.- Hide quoted text -

- Show quoted text -

- If the timing is advanced too far, it will burn a hole in the piston
or detonate it self to death.

THEN do I get to buy a new one? ;-)

You could buy a new one now.

I agree with Steve, you could do some serious damage by running it without
fixing it first. My next door neighboor tried to "get a few more mowings"
out of a motor that need to be on full choke to run. Totally messed up the
valves. He got to buy a new one.

"Steve Barker LT" wrote in message
...
It does sound like the timing has advanced. And the only way for that to
happen is for the key in the flywheel to shear and the flywheel slip on
the crank. I'd check that first.

s

OR you have some really **** poor gas. G


Gasoline contaminated with kerosene can have the same effect.

Don Young

"DerbyDad03" wrote in message
oups.com...
I've got a Toro mower (Model 20016) with a 4 cycle Tecumseh engine
that is trying to hurt me.

When I try to start it, the start cable will pull out about half-way,
under normal starting tension, and then it feels like the compression
of the engine trys to yank it back in. It will violently pull my arm
back towards the mower.

When it eventually does start, there are 3 - 4 loud knocks (*not*
backfires) and then the mower runs fairly normally. I say "fairly
normally" because it no longer runs as smooth and quiet as it used
too.

The mower is at least 4 years old. Should I be looking at the fall
sales flyers?

On Sep 15, 5:29 pm, DerbyDad03 wrote:
On Sep 15, 8:01 pm, "Steve Barker LT"
wrote:





If the timing is advanced too far, it will burn a hole in the piston or
detonate it self to death.

steve

"DerbyDad03" wrote in message

ups.com...

Assuming the FW key is the problem, how bad is it for the mower to run
like this? It's September in Upstate NY, so I only have a few more
mows before I'd be putting it up for the winter anyway. I'd just as
soon wait until the season's over before my first foray into small
engine repair.- Hide quoted text -

- Show quoted text -

- If the timing is advanced too far, it will burn a hole in the piston
or detonate it self to death.

THEN do I get to buy a new one? ;-)- Hide quoted text -

- Show quoted text -

Be sure to get the correct key, it will be made of softer metal, not
steel. They are designed to shear if the blade hits something solid
so that the motor itself is not wrecked by a sudden stop. It probably
is not sheared completely, even a slight 'nick' will throw the timing
off.

Harry K

Harry K

sure. If you've got money to blow and are wasteful. go for it. Hell, put
it in the dumpster now and buy a new one. Why wait? No need to make a
simple repair when you can have new new new stuff and outshine your
neighbor.


s


"DerbyDad03" wrote in message
ups.com...

THEN do I get to buy a new one? ;-)

Oren wrote:

snipped



About the hammering on the shaft. I use a block of wood to deaden the
blow AND I always leave the loosened nut on the shaft. It prevents
damaged to the thread.

And it keeps the flywheel from flying off if you're pulling up on it
real hard, and whacking you in the forehead. (DAMHIKT)

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.98*10^14 fathoms per fortnight.

DerbyDad03 wrote:

Assuming the FW key is the problem, how bad is it for the mower to run
like this? It's September in Upstate NY, so I only have a few more
mows before I'd be putting it up for the winter anyway. I'd just as
soon wait until the season's over before my first foray into small
engine repair.

Your choice. It'll take less time to fix than to buy a new one.

On 17 Sep, 09:18, "Stormin Mormon"
wrote:
The last time I had one do that, the blade was loose from the crank shaft.
Flip the mower on its side, and see if the blade is tight.

The other person's suggestion about flywheel out of time, that's also very
possible.

--
.
Christopher A. Young
Learn more about Jesus
http://www.lds.org/portal/site/LDSOrg
http://www.mormon.org/mormonorg/eng/
."DerbyDad03" wrote in message

oups.com...
: I've got a Toro mower (Model 20016) with a 4 cycle Tecumseh engine
: that is trying to hurt me.
:
: When I try to start it, the start cable will pull out about half-way,
: under normal starting tension, and then it feels like the compression
: of the engine trys to yank it back in. It will violently pull my arm
: back towards the mower.
:
: When it eventually does start, there are 3 - 4 loud knocks (*not*
: backfires) and then the mower runs fairly normally. I say "fairly
: normally" because it no longer runs as smooth and quiet as it used
: too.
:
: The mower is at least 4 years old. Should I be looking at the fall
: sales flyers?
:

Thank you for ignoring the 3rd reply in this thread. :-)

On Sun, 16 Sep 2007 12:32:14 -0400, Jeff Wisnia
wrote:

Oren wrote:

snipped

About the hammering on the shaft. I use a block of wood to deaden the
blow AND I always leave the loosened nut on the shaft. It prevents
damaged to the thread.

And it keeps the flywheel from flying off if you're pulling up on it
real hard, and whacking you in the forehead. (DAMHIKT)

How _old_ is your T-shirt? :-/

--
Oren

...through the use of electrical or duct tape, achieve the configuration in the photo..

"DerbyDad03" wrote in message
ps.com...
On Sep 15, 6:10 pm, Oren wrote:
On Sat, 15 Sep 2007 15:34:19 -0400, Meat Plow
wrote:

The key ensures the
proper position of the flywheel so there is no guesswork.

They can be a booger now and then; when placing the FW on. The key
might slip a tad. I use a tiny bit a grease to help hold the key in
the crank slot - if I ever have to do it again.

--
Oren

"Well, it doesn't happen all the time, but when it happens, it happens
constantly."

Assuming the FW key is the problem, how bad is it for the mower to run
like this? It's September in Upstate NY, so I only have a few more
mows before I'd be putting it up for the winter anyway. I'd just as
soon wait until the season's over before my first foray into small
engine repair.


The next time you start it, the rope will break. Then you'll need to fix that
too.

It's not that big of a deal to fix. Get brave and give it a try.

http://repairfaq.ece.drexel.edu/sam/lmfaq.htm

Bob

On 17 Sep, 21:26, "Bob F" wrote:
"DerbyDad03" wrote in message

ps.com...





On Sep 15, 6:10 pm, Oren wrote:
On Sat, 15 Sep 2007 15:34:19 -0400, Meat Plow
wrote:

The key ensures the
proper position of the flywheel so there is no guesswork.

They can be a booger now and then; when placing the FW on. The key
might slip a tad. I use a tiny bit a grease to help hold the key in
the crank slot - if I ever have to do it again.

--
Oren

"Well, it doesn't happen all the time, but when it happens, it happens
constantly."

Assuming the FW key is the problem, how bad is it for the mower to run
like this? It's September in Upstate NY, so I only have a few more
mows before I'd be putting it up for the winter anyway. I'd just as
soon wait until the season's over before my first foray into small
engine repair.

The next time you start it, the rope will break. Then you'll need to fix that
too.

It's not that big of a deal to fix. Get brave and give it a try.

http://repairfaq.ece.drexel.edu/sam/lmfaq.htm

Bob- Hide quoted text -

- Show quoted text -

A note of thanks to all who offered help...

So I finally decided to attack the mower last weekend - I mowed
Saturday morning and had no problems other than the hard starts and
knocking, same symptoms as before.

Later that day my son tried to start the mower and found that the
blade was extremely loose, which was not the case during earlier
inspections. He tightened the blade, tried to start it again and the
blade loosened up immediately. It turned out that in addition to the
starting problems, the welds on the driver-blade assembly had broken
free. This is the part that not only secures the blade to the shaft,
but also has the pully that powers the front-wheel drive.

Now I have to either fix or trash the mower. I pulled the engine cover
and shroud to find (as many you suggested) that the flywheel key was
broken and the flywheel had shifted significantly. Now I had to figure
out how to get the flywheel off. A quick Google search found this page
which shows a home made tool for pulling the flywheel on Tucumseh
engine:

http://repairfaq.ece.drexel.edu/sam/lmfaq.htm#lmflyrml

Coincidentally, that's located at the same repair site that Bob
suggested.

Anyway, 15 minutes later I had the flywheel off and was on my way to
the mower repair shop. $70 dollars later I had a flywheel key, a
driver-blade assembly, a drive belt and a new mulching blade. Since
the mower absolutely needed a blade anyway, I figure the repair cost
was really only $50.

The mower now starts with no more than 2 pulls when cold, half a pull
when warm.

Thanks again!

On Oct 17, 6:34 am, DerbyDad03 wrote:
On 17 Sep, 21:26, "Bob F" wrote:





"DerbyDad03" wrote in message

ups.com...

On Sep 15, 6:10 pm, Oren wrote:
On Sat, 15 Sep 2007 15:34:19 -0400, Meat Plow
wrote:

The key ensures the
proper position of the flywheel so there is no guesswork.

They can be a booger now and then; when placing the FW on. The key
might slip a tad. I use a tiny bit a grease to help hold the key in
the crank slot - if I ever have to do it again.

--
Oren

"Well, it doesn't happen all the time, but when it happens, it happens
constantly."

Assuming the FW key is the problem, how bad is it for the mower to run
like this? It's September in Upstate NY, so I only have a few more
mows before I'd be putting it up for the winter anyway. I'd just as
soon wait until the season's over before my first foray into small
engine repair.

The next time you start it, the rope will break. Then you'll need to fix that
too.

It's not that big of a deal to fix. Get brave and give it a try.

http://repairfaq.ece.drexel.edu/sam/lmfaq.htm

Bob- Hide quoted text -

- Show quoted text -

A note of thanks to all who offered help...

So I finally decided to attack the mower last weekend - I mowed
Saturday morning and had no problems other than the hard starts and
knocking, same symptoms as before.

Later that day my son tried to start the mower and found that the
blade was extremely loose, which was not the case during earlier
inspections. He tightened the blade, tried to start it again and the
blade loosened up immediately. It turned out that in addition to the
starting problems, the welds on the driver-blade assembly had broken
free. This is the part that not only secures the blade to the shaft,
but also has the pully that powers the front-wheel drive.

Now I have to either fix or trash the mower. I pulled the engine cover
and shroud to find (as many you suggested) that the flywheel key was
broken and the flywheel had shifted significantly. Now I had to figure
out how to get the flywheel off. A quick Google search found this page
which shows a home made tool for pulling the flywheel on Tucumseh
engine:

http://repairfaq.ece.drexel.edu/sam/lmfaq.htm#lmflyrml

Coincidentally, that's located at the same repair site that Bob
suggested.

Anyway, 15 minutes later I had the flywheel off and was on my way to
the mower repair shop. $70 dollars later I had a flywheel key, a
driver-blade assembly, a drive belt and a new mulching blade. Since
the mower absolutely needed a blade anyway, I figure the repair cost
was really only $50.

The mower now starts with no more than 2 pulls when cold, half a pull
when warm.

Thanks again!- Hide quoted text -

- Show quoted text -

Thanks for the update.

Harry K

"DerbyDad03" wrote in message
It's not that big of a deal to fix. Get brave and give it a try.

http://repairfaq.ece.drexel.edu/sam/lmfaq.htm

Bob- Hide quoted text -

- Show quoted text -

A note of thanks to all who offered help...

So I finally decided to attack the mower last weekend - I mowed
Saturday morning and had no problems other than the hard starts and
knocking, same symptoms as before.

Later that day my son tried to start the mower and found that the
blade was extremely loose, which was not the case during earlier
inspections. He tightened the blade, tried to start it again and the
blade loosened up immediately. It turned out that in addition to the
starting problems, the welds on the driver-blade assembly had broken
free. This is the part that not only secures the blade to the shaft,
but also has the pully that powers the front-wheel drive.

Now I have to either fix or trash the mower. I pulled the engine cover
and shroud to find (as many you suggested) that the flywheel key was
broken and the flywheel had shifted significantly. Now I had to figure
out how to get the flywheel off. A quick Google search found this page
which shows a home made tool for pulling the flywheel on Tucumseh
engine:

http://repairfaq.ece.drexel.edu/sam/lmfaq.htm#lmflyrml

Coincidentally, that's located at the same repair site that Bob
suggested.

Anyway, 15 minutes later I had the flywheel off and was on my way to
the mower repair shop. $70 dollars later I had a flywheel key, a
driver-blade assembly, a drive belt and a new mulching blade. Since
the mower absolutely needed a blade anyway, I figure the repair cost
was really only $50.

The mower now starts with no more than 2 pulls when cold, half a pull
when warm.

And the next time, you can answer this question.

Bob