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Greetings,

Curious, anyone ever see a Briggs Stratton 26HP Intek just stop with nothing and no noise, no locked engine, just no piston movement, but valves work fine on both heads. One piston at top and the other at bottom. How is it possible for both roda to let go at same time with no lock up of engine or any interference indications. Engine was running great before and now just cranks freely?

Thanks,

If both pistons are not moving you will have to open the engine up to diagnose the problem.

Same thing happened to my neighbours B&S 23 hp twin (only one piston). In process of acquiring a new engine.

Rivets said:

If both pistons are not moving you will have to open the engine up to diagnose the problem.

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Thanks, I figured this was obvious, but to pull engine and take apart to see issue and find it is not worth fixing was my question, it just seemed totally strange to have both rods go and no lock up or noises. Was just deciding to part out or repair, so thanks.

Skippydiesel said:

Same thing happened to my neighbours B&S 23 hp twin (only one piston). In process of acquiring a new engine.

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Thanks, I agree, one rod going is common, but both at same time just seemed to odd to me and I was just curious if anyone ever saw this happen before. I didn't want to remove motor and open up until I had an idea if this was even possible. I bought it with seller just telling me it wouldn't start, turned over, so I thought it was the typical carb clog issue. Didn't want to waste time so will part it out.

This is one time I would be taking it apart to find the cause. Never to old to learn something new, because this is so rare and haven’t seen it before.

Rivets said:

This is one time I would be taking it apart to find the cause. Never to old to learn something new, because this is so rare and haven’t seen it before.

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My suspicions are that it failed from lack of lube and when one rod broke it interferred and broke the second rod. Or they both broke from lack of lube and both seized and broke about the same time.

I’m wondering if one broke, it was running for a while on one cylinder, then the other one broke. I’ve seen more than on engine running on one cylinder and the customer didn’t even notice it.

Rivets said:

I’m wondering if one broke, it was running for a while on one cylinder, then the other one broke. I’ve seen more than on engine running on one cylinder and the customer didn’t even notice it.

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Very possible.

Rivets said:

This is one time I would be taking it apart to find the cause. Never to old to learn something new, because this is so rare and haven’t seen it before.

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An engine autopsy is in order here. Seeing the damage is sometimes worth the effort for a learning experience.

ILENGINE said:

My suspicions are that it failed from lack of lube and when one rod broke it interferred and broke the second rod. Or they both broke from lack of lube and both seized and broke about the same time.

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Thanks, that would be normal, and why this is so strange is there is no interference, no noise, just spins freely. I had purchased another Intek years ago and it would not turn over by hand it would hit a lock point, and was rod, and it jammed up flywheel, as in, normally what happens when a rod let got. It was an overheat issue, clogged up cooling fins to the max, never cleaned, but this one was clean, strange. It also had full crank with oil and valves all working, so cam is OK, so was just curious if anyone else ever came across this before I decide to unload it to someone who wants to rebuild.

Tiger Small Engine said:

An engine autopsy is in order here. Seeing the damage is sometimes worth the effort for a learning experience.

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Thanks, no doubt opening it up is the only way to know for sure, but I was just curious as I would never have expected both rods letting go at same time with zero interference as engine spins freely and cam is OK as all valves open and shut. Just not sure I want to know what or how this happened, so deciding to sell it off to someone who is able to rebuild engine.

A sheared flywheel key with a slightly loose bolt / nut will allow the flywheel to turn on the shaft but the shaft not turn in the engine
So get under the mower and try turning the drive pulley by pulling on the belt .

0NPASSIVE said:

Greetings,

Curious, anyone ever see a Briggs Stratton 26HP Intek just stop with nothing and no noise, no locked engine, just no piston movement, but valves work fine on both heads. One piston at top and the other at bottom. How is it possible for both roda to let go at same time with no lock up of engine or any interference indications. Engine was running great before and now just cranks freely?

Thanks,

Click to expand...

Odd that both rods would break with no noise whatsoever, but it sounds like that is exactly what happened. Pistons not moving but valves are working pretty much says two failed rods. Worst case you need a short block. Best case is a less than proper fix (IMHO) of two rods and maybe cleaning up the crank journal.

0NPASSIVE said:

Greetings,

Curious, anyone ever see a Briggs Stratton 26HP Intek just stop with nothing and no noise, no locked engine, just no piston movement, but valves work fine on both heads. One piston at top and the other at bottom. How is it possible for both roda to let go at same time with no lock up of engine or any interference indications. Engine was running great before and now just cranks freely?

Thanks,

Click to expand...

believe that engine doesn’t want to live anymore

0NPASSIVE said:

Greetings,

Curious, anyone ever see a Briggs Stratton 26HP Intek just stop with nothing and no noise, no locked engine, just no piston movement, but valves work fine on both heads. One piston at top and the other at bottom. How is it possible for both roda to let go at same time with no lock up of engine or any interference indications. Engine was running great before and now just cranks freely?

Thanks,

Click to expand...

My first thought was maybe the crankshaft snapped but I am not sure. Disassembly is the key to finding out what went wrong.

0NPASSIVE said:

Thanks, I figured this was obvious, but to pull engine and take apart to see issue and find it is not worth fixing was my question, it just seemed totally strange to have both rods go and no lock up or noises. Was just deciding to part out or repair, so thanks.

Click to expand...

Almost sounds like a broken crank! It sounds like this may be a common issue with this engine and maybe worth a call to B&S to speak with their Tech! Complete engines are EXPENSIVE these days, so may be worth a couple hundred to fix it - IF they will warranty the engine after repair.

Air4Dave said:

Almost sounds like a broken crank! It sounds like this may be a common issue with this engine and maybe worth a call to B&S to speak with their Tech! Complete engines are EXPENSIVE these days, so may be worth a couple hundred to fix it - IF they will warranty the engine after repair.

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The only issue with that is the valves are moving, and since the camshaft is driven off the pto end of the crankshaft, the crank from the flywheel to at least the timing gear would have to be intact which would include the rod bearing area of the crankshaft.

This is odd. If it was mine, I'd have to take the time to tear into the engine just to see what happened and why it happened. But that's just me.

Firstly, I'm not familiar with type of engine on your mower. You say the valves are working. Now, if the cam lobes are above the crank, then it's possible the crank shaft broke just above the crank throw (between it and the part of the shaft that the cam lobes are located).
That happened on a Kinner five cylinder radial engine. The story is long and the description is very complicated.
That engine is not in any way similar to a lawn mower engine. I only mention it to point out that a broken crank shaft is possible.
If any one wants to read the story, contact me at jimbir@yahoo.com. Just put "Kinner crank shaft" in the subject line. Don't be in a hurry for a reply. It's going take quite a while for me to compose the thing in my spare time.

Can you access both ends of the crank? Valves move because you are turning the crank at the end with the drive gear for the cam. I would guess that the other end of the crank does not turn when you turn the end that you are turning. I know nothing about lawn mower engines, but that is my theory after looking at the parts breakdown.
It also looks like there is only one throw on the crank. Do both pistons move up and down together?

Is the engine still on the mower?
Is the starter spinning the flywheel? (You seem to indicate that you can turn the flywheel?)
Does the PTO end of the crank turn when the flywheel turns? Was the engine running when it happened or did you just go to start the engine and failure?

Reason I ask is the crankshaft either broke above the first rod and below the flywheel or the flywheel came loose???

I've never seen either but as the other guys indicate it needs to be checked further.
It needs an autopsy and a colonoscopy.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

ILENGINE said:

The only issue with that is the valves are moving, and since the camshaft is driven off the pto end of the crankshaft, the crank from the flywheel to at least the timing gear would have to be intact which would include the rod bearing area of the crankshaft.

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I can see that happening. This appears - per the above discussions - that this is not an isolated issue! One that B&S should certainly be aware of and offer some kind of assistance! It could be an isolated bad batch of crankshafts or, more likely, connecting rods/bearings. Unfortunately, most manufacturers these days don't want to do the ethically correct thing and pay for part of the repairs.

Air4Dave said:

I can see that happening. This appears - per the above discussions - that this is not an isolated issue! One that B&S should certainly be aware of and offer some kind of assistance! It could be an isolated bad batch of crankshafts or, more likely, connecting rods/bearings. Unfortunately, most manufacturers these days don't want to do the ethically correct thing and pay for part of the repairs.

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There are more questions than answers and since the OP hasn't been here since May 25 we may never get those answers. With a little research I can't find a model LT 4500 but did find a YT 4500 which was made before 2014 so if that is true this engine is at least 10 years old. And the 26 hp engine that they list was the Kohler Courage 26 hp so may not even be a Briggs. So if what I found is true I am not going to blame the issue on a bad batch and crankshafts, or connecting rods/bearings. And I don't know of a single manufacturer of any brand that would pay for repairs or parts on a 10 year old engine.

ILENGINE said:

There are more questions than answers and since the OP hasn't been here since May 25 we may never get those answers. With a little research I can't find a model LT 4500 but did find a YT 4500 which was made before 2014 so if that is true this engine is at least 10 years old. And the 26 hp engine that they list was the Kohler Courage 26 hp so may not even be a Briggs. So if what I found is true I am not going to blame the issue on a bad batch and crankshafts, or connecting rods/bearings. And I don't know of a single manufacturer of any brand that would pay for repairs or parts on a 10 year old engine.

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Agree! Thanks for looking further into this. I didn't have any idea this engine is that old! I, too, have a T2400 w/the B&S engine but it runs just fine. It's also 10 years old and I just got it from my neighbor in a trade. It wasn't taken care of very well, as far as the blades, seat, lubrication, and steering, but I've replaced and/or fixed it back to good working order. Fortunately, he DID take care of the engine!

I like the way every one starts to jump to conclusions without recommending some simple tests , like turning the engine from the PTO shaft end and seeing if the pistons move
Consider this.
Engine seizes & flywheel spins on taper thus becoming loose
Starter spins flywheel but flywheel is not spinning the crank because the engine is locked up tight as a drum
This will happen if the oil is a bit low and the owner is driving along a slop with the oil pick up on the high side