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Hi,

I was trying to start my mower for the first time of the season. I was pulling the cord and it was working correctly, but wasn't starting at all. I then checked the oil and it was off the stick. I filled it with oil, but now the handle won't pull at all. If I turn the blade by hand it goes about 330 degrees around, but on each way of turning seems to hit something. I've inspected it pretty well and it's not hitting anything underneath for sure. I took off the shrouds or covers on the top and can't see anything it's hitting there either. I also read about hydraulic lock resulting from tipping it the wrong way (which is a good possibility) so I pulled the plug and moved it back and forth a bunch of times, but nothing changed. The shaft doesn't seem bent or wobbly or loose. Any ideas? If it seized (which to me seems unlikely because it never actually started), would I still be able to turn the blade?

Thanks,

Andy

Two things come to mind. One the rod is broken, which can be checked by looking through the spark plug hole while turning the blade, and see if the piston moves up and down. The other thing is a piece of carbon or something is on top of the piston preventing it from reaching top dead center.

ILENGINE said:

Two things come to mind. One the rod is broken, which can be checked by looking through the spark plug hole while turning the blade, and see if the piston moves up and down. The other thing is a piece of carbon or something is on top of the piston preventing it from reaching top dead center.

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I looked through the hole, but don't see anything moving. I take it the next step is to pull the head? Or would it hurt to give it a couple love taps to see if I can get it past the point it stops? Thanks for you help by the way. -Andy

First I would make sure the ignition module isn't actually hitting the flywheel magnet. then barring that I would pull the head and see what it looks like in there.

fairbs said:

I looked through the hole, but don't see anything moving. I take it the next step is to pull the head? Or would it hurt to give it a couple love taps to see if I can get it past the point it stops? Thanks for you help by the way. -Andy

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And no you will not hit it with a hammer.
If it won't rotate then something is wrong all smacking it with a hammer till do is bend or brek whatever is cusing the problem so the bekt part can then go through the cases and total the engine.

You said with spark plug out you could not see anything moving, with plug out take a screw driver that will fit thru hole and push it in till it is against the piston, while holding pressure on screw driver turn the blade with other hand and if the piston doesn't move then you have a broken rod.
If that is the case you have a major internal problem, it will need to be opened up to see what the damage is, if piston moves you can take head off and see if a piece of carbon or a screw was sucked thru carburetor.
Let us know what you find, Good Luck !

ILENGINE said:

First I would make sure the ignition module isn't actually hitting the flywheel magnet. then barring that I would pull the head and see what it looks like in there.

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I pulled what I think is the head. I now know why I couldn't see anything moving because the piston is away from where the spark plug attaches. I've also found why the blade wouldn't turn all the way around. There was a small sliver of the top of the piston chipped off and that was stopping it from reaching its highpoint. With the head off, I can now rotate the blade fully and the piston moves up and down. So now the big questions are: is it worth fixing? does the piston need replacing? I was pulling it apart quickly before work, but I could provide a picture if that would help assess the damage.

Please post picture of piston and the head so we can see what damage you have, also take your hand with piston all the way up and try to move it side to side and tell us how much movement, it would also be good to have picture of cylinder wall with piston all the way down.

Usually a "sliver off the top" will be chunk from the ring grove to the crown.
This means the top ring will not be able to seal properly and the engine will be some where between a little smokey to a moving smoke screen.
If the bore is OK , which is why you were adviced to not to force it you will get away with a new piston or piston & rod which are not very expensive.
Again we will need the pickies.

Look closely at the piston top as something caused that lump to break off.
Very early you do get a piston cracked from new but mostly it is because something got into the cylinder that should not have been there, screws from the carb are a prime example.

Tecumseh engine and no oil showing on the dip stick.

Buy a new engine at minimum or buy a new mower.

SeniorCitizen said:

Tecumseh engine and no oil showing on the dip stick.

Buy a new engine at minimum or buy a new mower.

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OK went back to the start.
No oil on the dip stick so we will assume it ended the season with no oil and now has a broken piston, I will have to agree with the diagnosis of Dr S Citizen.
Patient is terminal and a cemetary plot is in order.

bertsmobile1 said:

Usually a "sliver off the top" will be chunk from the ring grove to the crown.
This means the top ring will not be able to seal properly and the engine will be some where between a little smokey to a moving smoke screen.
If the bore is OK , which is why you were adviced to not to force it you will get away with a new piston or piston & rod which are not very expensive.
Again we will need the pickies.

Look closely at the piston top as something caused that lump to break off.
Very early you do get a piston cracked from new but mostly it is because something got into the cylinder that should not have been there, screws from the carb are a prime example.

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I wasn't able to get the pictures last night, but I will tonight including the cylinder wall and I'll investigate closely as well. Thanks for the advice.

bertsmobile1 said:

Usually a "sliver off the top" will be chunk from the ring grove to the crown.
This means the top ring will not be able to seal properly and the engine will be some where between a little smokey to a moving smoke screen.
If the bore is OK , which is why you were adviced to not to force it you will get away with a new piston or piston & rod which are not very expensive.
Again we will need the pickies.

Look closely at the piston top as something caused that lump to break off.
Very early you do get a piston cracked from new but mostly it is because something got into the cylinder that should not have been there, screws from the carb are a prime example.

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Not sure how these will look...





The sliver is about 2.5cm long. On the picture with the rule, there is a little, lets call it a burr, that sticks out (by the 6 on the ruler) from the sliver itself. That's scratched the cylinder wall some mostly near the top which you can kind of see in the other picture. I didn't find any screws or loose metal in the cylinder other than a couple of other very small chips which I believe came from where the sliver once lived.

The engine is scrap metal.
not repairable.
If the mower is good then look for a replacement engine

I would have said that the piston was full of oil from the mower being tilted...ran past intake valve into cylinder.
Did you try and pull the cord with the spark plug out and no compression?

Turn the blade with the spark plug out?

shiftsuper175607 said:

I would have said that the piston was full of oil from the mower being tilted...ran past intake valve into cylinder.
Did you try and pull the cord with the spark plug out and no compression?

Turn the blade with the spark plug out?

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I did try to turn it and it would make a wheezing noise, but stop at a certain point. I'm guessing at somewhere during my futzing, the sliver found its way to a point where the piston couldn't make a full revolution because when I first pulled the mower out, I was able to pull the cord fine, but it just wouldn't start.

Thanks everyone for the help. I've learned a lot. It looks like I need to decide on whether to buy a new engine or new mower. The old mower got at least a decade of use so it had a decent life. Unfortunately, every year something would go wrong where it wouldn't start up on the first outing and that usually meant digging into the carb either a little or a lot. So in some ways, it won't be all that missed as long as the new one isn't worse.