Lawn Mower Problem

Page 1 of 2  
We have a rear bagger mulching push mower. I accidentally ran over a very thick tree route and it literally knocked the blade right off. I was able to put the blade back on and when I manually turn it it freely spins around but when I try to start the mower it won't start, it makes a loud clunking sound and the pull rope sometimes only comes out about half way and abruptly stops. Anyone have any conjecture as to the nature of the repair and whether it would be less costly to just get a new mower for a couple hundred bucks?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I would bet that you have broken internal parts and that could be very costly.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

It seems very likely that you broke the "shear pin" that holds the flywheel to the crankshaft and keeps it in place. You need a puller to remove the flywheel. Don't pound on it with a hammer or you might break it or damage the magnet. Once you get the flywheel off you may find, as someone else pointed out, that it has other damage too. New shear pins are usually available at hardware stores in the lawn mower parts section.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I was thinking flywheel key. But, also, bent crank shaft. I'd try replacing the flywheel key. But if it's still not running, or runs but shakes violently, might be beyond simple repair.
--
Christopher A. Young
Learn more about Jesus
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Ulysses wrote:

shear pin, (which they don't have) won't keep it from turning.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Shear key then. Do they have those?
A misaligned ignition module could keep it from turning.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 11 May 2009 21:29:45 -0500, Steve Barker

ignition on a challenge. (spark occurs with the piston just over half way up - yank the cord right out of your hand
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@snyder.on.ca wrote:

agreed, this is a common failure with Tecumseh engines. I had a handful of Tecumseh flywheel keys on a shelf in my garage when I lived in Michigan. My neighbor/landlord was always bringing his mower over for me to fix and it was always the same failure, I guess they were hard on mowers/never picked up all the rocks in their yard/mowed right over roots and stumps. Inevitably it was the flywheel key (a soft metal key on those, not a pin) the reason it won't start is because the trigger for the ignition is on the flywheel, once the flywheel spins on the crank the engine is out of time. Starts running bad the first time you hit something and if you hit another something it'll knock it so far out that it won't start anymore... symptoms exactly like the OP's. Kicks back when you start, etc. (because the timing is too far advanced for the engine to run)
The fact that I could "fix" lawnmowers and was able to repair a busted window and "restore" (really just strip off years of sloppy painting and re-clear) the old brass door hardware got me loads of brownie points. I think I also tarred the cracks in the sidewalk so the weeds wouldn't grow up through, edged the walk, weeded the flower beds (actually I usually just threw my grass clippings in them and then only pulled up the weeds that managed to get through all that,) and did a couple other little things and my landlord was just blown away. Makes you wonder what the average tenant was like...?
nate
--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Wow! You must have one of those nifty press-on blades
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Jeffy3 wrote:

FUBAR!
Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat \'57 EE)
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The only way to be sure is to look at it, since I can't, I'll offer a couple suggestions.
After putting the blade back on, tie down the auto stop and remove the spark plug (so it doesn't start) and turn the blade around. Does it wobble? Is the blade bent? Is the crank bent? If everything looks straight and true, then pull the flywheel cover off and spin it aroound to see if it wobbles or the crank wobbles.
If the crank is wobbling, throw it in the trash. If the crank doesn't wobble, remove the blade and the flywheel and turn it to make sure it isn't the crank and the "sounds" you hear aren't coming from the blade or flywheel. If you still hear sounds, you more than likely have serious problems. Trash it.
Hank
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Thank you all for your responses. I did leave out one detail but have no idea if it's relevant or would change anyone's opinion. At one point when I was trying to start the mower, I realized I had forgotten to connect the spark plug. When the spark plug isn't attached, the pull rope operates fine. As soon as the spark plug is connected, the pull rope acts up and the clanking sound starts
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Sounds like the shear pin, and the timing is off. Pull the plug out to examine if the piston is moving through the four strokes. (have a compression tester?)
The rope will jerk your arm back when the timing is off and the plug is connected.
Does the noise exist when the plug is out and you yank the cord 5 times?
btw, I've never seen a mower blade "knocked" off.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

He doesn't need a compression tester for a lawn mower that was working well a little while ago.
Since it's a one cylinder engine, you don't need to disable the other cylinders, so just take out the one spark plug and put your thumb over the hole. If you feel pressure pushing your thumb off every so often, you have compression. That is, at least one valve is opening (but probably both) and then they are both closing, and the piston is moving up in the cylinder. If you have any compression, I'm sure you have adequate compression, give that you hit a route, or root. :)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
mm wrote:

HE SAID the som bitch turns then stops! It's broke! duh!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 11 May 2009 23:00:14 -0500, Steve Barker

If one plans to fix it, it should eventually have compression, duh.
And my post was a general statemnt about the need for a compression tester on a lawnmower that was recently running well.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Jeffy3 wrote:

If the blade is tight, this clinches it. The flywheel key is sheared. The timing is way off, causing the engine to missfire, thus the clunk. A loose blade can cause similar symptoms on some engines.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

I would check the gizmo that stops the engine when you release the handle. See if that's stopping the engine from turning. If so, it's fixable. If not, start shopping.
Oh yeah, I always follow engine repair tips from guys who call key parts gizmos...
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.