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ofranzen


Joined: Dec 26, 2005
Points: 19

Sheared a second flywheel key on my Tecumseh HS50
Original Message   Jan 25, 2006 3:28 pm
I'm continuing my quest in a new thread now that I have a more specific question. Old thread is http://www.abbysguide.com/ope/discussions/19249-0-1.html

I got a new flywheel key as the old turned out to be broken. The new one broke after about three pulls and one ignition...

The new key looks like a dud though. The sheared surface looks dimpled as if the metal had bubbles in it. The old one looked solid and the sheared surface is smooth.

Could I have been so unlucky that I got a bad new key or is a second broken key a sign on some other problem? If I remove the spark plug and turn the flywheel, it seems to run smooth.

/Ola

Replies: 1 - 7 of 7View as Outline
70chevrolet


Location: Mansfield, MA
Joined: Dec 6, 2005
Points: 120

Re: Sheared a second flywheel key on my Tecumseh HS50
Reply #1   Jan 25, 2006 4:06 pm
Once I sheared 3 in a row on my 70 Vespa Sprint.. Turns out I wasnt tightening the flywheel down with a torque wrench and it wasnt tight enough... I learned that one the hard way. Havent sheared on since.
ofranzen


Joined: Dec 26, 2005
Points: 19

Re: Sheared a second flywheel key on my Tecumseh HS50
Reply #2   Jan 25, 2006 4:30 pm
Good call! I'll make sure I tighten the nut more next time. I was a bit surprised at how easy it was to get the nut off the first time so maybe that's why the first broke.

Thanks for the tip.

spottedpony


Joined: Aug 23, 2004
Points: 301

Re: Sheared a second flywheel key on my Tecumseh HS50
Reply #3   Jan 26, 2006 12:50 am
70chevrolet wrote:
Turns out I wasnt tightening the flywheel down with a torque wrench and it wasnt tight enough

Right on the money i think. If you look inside the flywheel at the center hub it should be etcentric....the cam lobe in the flywheel is what opens and closes the points on a point type ignition, or triggers the sensor for electronic ignition. All the key does is keeps the ignition in time.  The end of the crankshaft is tapered matching the configuration in the flywheel, & actually is held by pressure from the bolt pulling the flywheel onto the tapered shaft,  so torque on the bolt is critical, too loose & the flywheel can turn thus shearing the key,
ofranzen


Joined: Dec 26, 2005
Points: 19

Re: Sheared a second flywheel key on my Tecumseh HS50
Reply #4   Jan 26, 2006 5:45 pm
Success!

I got me a decent torque wrench and cleaned the surfaces properly before assembling this time. No problems at all and the engine started on the second pull :)

Thanks

/Ola

jubol


Location: Dover, De
Joined: Oct 3, 2003
Points: 1558

Re: Sheared a second flywheel key on my Tecumseh HS50
Reply #5   Jan 26, 2006 5:52 pm
OFR,

Congrats!!

                         Fred

Husqvarna STE927(11.5HP) snowblower,  MTD Pro Series 18/42 Lawnmower, MTD 6.5 HP  Self Prop Lawn Mower,  Weedeater 1500 Blower, Web Gensis  2000 
hirschallan


If it aint broke don't fix it !!


Location: Northern Hills of NY
Joined: Aug 25, 2005
Points: 309

Re: Sheared a second flywheel key on my Tecumseh HS50
Reply #6   Jan 26, 2006 6:00 pm
ofranzen wrote:
Success!

I got me a decent torque wrench and cleaned the surfaces properly before assembling this time. No problems at all and the engine started on the second pull :)

Thanks

/Ola



OFR,

What was the setting on the torque wrench ?

ofranzen


Joined: Dec 26, 2005
Points: 19

Re: Sheared a second flywheel key on my Tecumseh HS50
Reply #7   Jan 26, 2006 6:27 pm
I set it to 62Nm/46ft. lbs. as the repair manual I have said.

Now I'll make some final ajdustments on the carburetor, change the oil and get a new belt for the blower fan and all should be in top shape. Feels good but I'm sure we will get *no* more snow this season.

Replies: 1 - 7 of 7View as Outline
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