Craftsman LT 4500 26HP Briggs Stratton Intek Both Pistons not moving

[0NPASSIVE]

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.

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.

 

[0NPASSIVE]

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

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.

 

[bertsmobile1]

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 .

 

[VegetiveSteam]

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,

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.

 

[semimechanicman]

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,

believe that engine doesn’t want to live anymore

 

[The Maintenance Guy]

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,

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

 

[Air4Dave]

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.

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.

 

[ILENGINE]

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.

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.

 

[rutbuster1]

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.

 

[jimbir]

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 [email protected]. 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.