# Flywheel won't turn more that 1 rotation



## MarkC (Jan 15, 2012)

After using my trusty old 1970s Ariens w/ 7hp Tecumseh for about 1/2 hr., it shut down (made and abrupt but slowing internal friction sound). I could not pull the cord by hand so I tried to turn the flywheel with a socket wrench. I was able to turn it, but not much more 1 full turn in each direction. When I turn on the electric start, the started motor just hums. I did recently rebuild carb, but it has run a twice since then for extended periods. The blower does burn oil and I was probably about 1/2 way down on oil when it happened. Any idea what's wrong? Or what to look at next? I have drained the oil and refilled. I also removed the spark plug and sprayed a little bit of WD40 in there.


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## td5771 (Feb 21, 2011)

same problem with a 5 hp ariens. it was too low on oil.

pull the plug, look down into the plug hole. you will see the intake and exhaust valves. turn the motor to try to get both valves in the down position.


looking in the hole the piston is off to the side. pour some oil in (you want it in the cylinder not on top of the valves) and let is sit a few minutes. then rotate engine as far as it will go the back the other way. do this for a while and it might free up.

there is some internal piston/cylinder damage but it may free up and run ok, mine did.

starter motor hums because it doesnt have enough power to spin the semi stuck motor. dont use it until it is fixed, you will just burn out the starter.

if it frees up all the way. pull the rope for a while to blow out excess oil, then a new plug gapped right, ensure oil level is right( some may leak down making it too high) and when it starts let it run at an idle or low throttle. if you have to start it at high throttle fine but back it off as soon as you can.


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## Shryp (Jan 1, 2011)

Also remove the belt first just to rule out any problems in places besides the engine.


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## HCBPH (Mar 8, 2011)

*Engine problems*

Will the engine turn more than a complete rotation or not? If not and it gets stuck in the same general area, I would suppect it connecting rod related. See if you can look in the plug hole with a light and while attempting to rotate the crank, does the piston actually move or not?

Need more diagnostics first before a real answer is found. Good luck


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## MarkC (Jan 15, 2012)

HCBPH - sorry the thread title made it a a little confusing. I can turn the flywheel about 1-1/4 rotations. After that it won't budge.


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## Talon1189 (Nov 30, 2011)

Pull the spark plug out of the hole and place a plastic drinking straw in the hole. Rotate the crankshaft......does the straw go up and down? If not you probably have a broken piston connecting rod and the motor will either need to be rebuilt or replaced...


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## twofishy4u (Dec 6, 2011)

sounds like you may have broke the piston rod.


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## Talon1189 (Nov 30, 2011)

I drag race 4 cylinder 2.0 liter turbo charged motors ........I have blown up a few of those over the years. A 1 cylinder motor is similar in theory ..... It is either blown or NOT........No in between. Good luck with all that you decide


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## MarkC (Jan 15, 2012)

Well i got a chance to really look thru the plug opening. The valves appear to be operating properly, but the the piston head kind of flops unevenly. Sometimes there's a little restistance but the flywheel will continue turning after a little force. Never more than 1-1/4 turns though. I guess a broken piston rod makes sense. You guys agree?


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## HCBPH (Mar 8, 2011)

*Rod*



MarkC said:


> Well i got a chance to really look thru the plug opening. The valves appear to be operating properly, but the the piston head kind of flops unevenly. Sometimes there's a little restistance but the flywheel will continue turning after a little force. Never more than 1-1/4 turns though. I guess a broken piston rod makes sense. You guys agree?


I wonder if the entire bottom end of the connecting rod broke or not - based on the comments. If in fact the piston is moving up and down, it may only be one side is broke of the bottom end of the rod. If the piston isn't moving at all, then the whole thing is likely broken.

Regardless, it sounds like it's time to tear it apart and find out what's wrong. There are a number of videos on Youtube showing teardown and rod issues. Look for those by Donyboy73, he has a number of videos out there and overall, very good. Here's one example on replacing a broken rod:


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## twofishy4u (Dec 6, 2011)

in my experience the rod breaks and something usually bangs the cylinder and puts a crack in it. So usually unfixable. Worth looking into though as rods are normally only $30 or so and gasket sets can be had for less than that.


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