My cub cadet 682 has no compression when I crank over on it the Pistons arnt moving it is an 18 horse magnum with only 400 hours on it so I don't think it is blown but I don't know why the Pistons arnt moving it has twin cylinder and neither one are moving that's another reason why I don't think it's blown.
682 cub cadet no compression
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wsdrake
Well-known member
Weston,
Welcome to the forum!
If neither piston is moving, you have two thrown rods. If the block isn't busted, it is time for a rebuild.
Also, this should be on the main forum, as the 682 is a garden tractor, not a lawn tractor. Not trying to ride your case, just letting you know before Charlie gets to you.
Welcome again!
Welcome to the forum!
If neither piston is moving, you have two thrown rods. If the block isn't busted, it is time for a rebuild.
Also, this should be on the main forum, as the 682 is a garden tractor, not a lawn tractor. Not trying to ride your case, just letting you know before Charlie gets to you.
Welcome again!
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- Allen Schumacher
Bill, kind of dumb question, you sure the starter is engaged all the way??? How does one break both rods??
wsdrake
Well-known member
Allen,
No I'm not sure- Just going by what Weston is saying. Here is how I came to my conclusion:
1.) Weston states that the engine has no compression, while he cranks on it. Since the engine cranks, this tells me the starter is presumably functioning correctly.
2.) Weston also states that neither piston is moving up or down in the cylinder. If neither piston is moving up or down, that means that the connection between the piston and the crankshaft is broken.
3.) Taking into account all the evidence, one logically concludes that the connecting rods are broken.
I agree- dual thrown rods are rare. After some thought I am thinking Weston misdiagnosed his problem.
Weston,
How did you check compression? Did you use a compression checker? How do you know both pistons are not moving up and down? I would double check your diagnosis. Here is what I would do:
Take a pencil and stick it down the spark plug hole, after removing the plug. Slowly rotate the engine by hand and see if the pencil moves. If it does, then then you know the piston is moving up and down. If the pencil does not move, then you know it is not. Repeat this test for the other cylinder.
If neither piston moves, then it is either broken rods or a broken crank. If they do move, we will cross that bridge when we get there.
No I'm not sure- Just going by what Weston is saying. Here is how I came to my conclusion:
1.) Weston states that the engine has no compression, while he cranks on it. Since the engine cranks, this tells me the starter is presumably functioning correctly.
2.) Weston also states that neither piston is moving up or down in the cylinder. If neither piston is moving up or down, that means that the connection between the piston and the crankshaft is broken.
3.) Taking into account all the evidence, one logically concludes that the connecting rods are broken.
I agree- dual thrown rods are rare. After some thought I am thinking Weston misdiagnosed his problem.
Weston,
How did you check compression? Did you use a compression checker? How do you know both pistons are not moving up and down? I would double check your diagnosis. Here is what I would do:
Take a pencil and stick it down the spark plug hole, after removing the plug. Slowly rotate the engine by hand and see if the pencil moves. If it does, then then you know the piston is moving up and down. If the pencil does not move, then you know it is not. Repeat this test for the other cylinder.
If neither piston moves, then it is either broken rods or a broken crank. If they do move, we will cross that bridge when we get there.
There's no point in tell Weston to go to the main forum board when everyone answers the question here anyway.
wsdrake
Well-known member
Charlie-
I'm sorry. Had to tell him before it slipped my mind. I have a bad habit of forgetting things.
Best to move the conversation to the main forum- Charlie done yelled at me!
I'm sorry. Had to tell him before it slipped my mind. I have a bad habit of forgetting things.
Best to move the conversation to the main forum- Charlie done yelled at me!
I put a piece of wire in the spark plug hole and marked it at the top of the hole then cranked on the engine and it was in the same spot the starter is engaging all the way I have all the panels taken off so I can see it and I checked for compression by putting my finger over the spark plug hole and there is no compression
wsdrake
Well-known member
Hi Weston,
OK, let me see if I have this straight. You placed a piece of wire in each cylinder, and the wire didn't move, correct? I figured the starter was good still.
The compression test with your finger is fine- I've done it myself many times. If it doesn't have compression, and you are positive the pistons are NOT moving, then it is normally one of two things: broken crankshaft or broken rod(s). One thing you can check for is to make sure the flywheel key hasn't sheared (this is where I would start). If you can, spin the PTO side of the crankshaft, and watch the front of the engine; if the flywheel doesn't move, I would check the flywheel key, and if the flywheel does move, it essentially means your engine needs bottom end work. You could also spin the engine over with the key (or by hand) and watch the PTO side of the engine to make sure it is also rotating. Let us know how it goes!
OK, let me see if I have this straight. You placed a piece of wire in each cylinder, and the wire didn't move, correct? I figured the starter was good still.
The compression test with your finger is fine- I've done it myself many times. If it doesn't have compression, and you are positive the pistons are NOT moving, then it is normally one of two things: broken crankshaft or broken rod(s). One thing you can check for is to make sure the flywheel key hasn't sheared (this is where I would start). If you can, spin the PTO side of the crankshaft, and watch the front of the engine; if the flywheel doesn't move, I would check the flywheel key, and if the flywheel does move, it essentially means your engine needs bottom end work. You could also spin the engine over with the key (or by hand) and watch the PTO side of the engine to make sure it is also rotating. Let us know how it goes!
