Loader Flipped my L48 Kubota

[ultrarunner]

A lot of the old car events now require a fire extinguisher...

 

[Soundguy]

Agree it's time for the new head. I missed it (somewhere in this thread probably) but how on earth does flipping a machine over result in a new water path internal to the head on the engine !!?? I don't understand the mode of failure.

Lets break down a couple possibilities....do you understand hydrolock?

Both valves for a cyl closed water ( fluid, oil, etc.. ) in cylinder, piston goes up.. er.. or tries to, and can't, because water is essentially uncompressable ( at these temps and pressures ).

So it's the old irresistable force meeting the immovable object.

many times you get bent connecting rods, damaged cranks, broken blocks, etc.. in this case, my bet is the webbing in the head over the combustion chamber had a spot that was a hair weaker than anything else in that pressure cylinder. Who knows, might have sucked up oil on one stroke and popped it on another then started drinking water.

headbolts might have stretched and let fluids in, then let it water hammer it.

lots of possibilities for these modes of failure.

 

[ovrszd]

do you understand hydrolock?

Both valves for a cyl closed water in cylinder, piston goes up.. er.. or tries to, and can't, because water is essentially uncompressable ( at these temps and pressures ).

So it's the old irresistable force meeting the immovable object.

many times you get bent connecting rods, damaged cranks, broken blocks, etc.. in this case, my bet is the webbing in the head over the combustion chamber had a spot that was a hair weaker than anything else in that pressure cylinder. Who knows, might have sucked up oil on one stroke and popped it on another then started drinking water.

headbolts might have stretched and let fluids in, then let it water hammer it.

lots of possibilities for these modes of failure.

Well explained.

The bold part clearly explains "a chain is only as strong as it's weakest link" theory.

 

[DrivewayMan]

Ordered a new head from Kumar Bros. Complete head with vales and gasket $799.99. It was $751 for the head, and they let me have the gasket for $49. Should have it in a couple days. I will keep you posted.

 

[ultrarunner]

Here's hoping for success...

 

[JWR]

The original post described a severe over-revving event with likely destructive combustion pressures and mechanical overload. The engine was stopped before multiple failures happened. But at one spot in the head combustion pressure broke an internal web to a water passage. The tough thing is that there could be other parts that got over-stressed and may not hold up after this. No real way to tell without putting it back together and running it.

Rbargeron -- I hear you and no doubt you are far more experienced than I with overrevving diesels. All evidence indicates that nothing touched that head other than compressed gases and antifreeze solution. I would be absolutely astounded that compressed gas ever broke through a partition in a cast metal head. [Have you actually known of a case of that happening for sure?] Surely the head gaskets would give long before that wouldn't they ? The rods too. What do think about maybe a mechanical impact crack of some sort ... but that would have left destructive marks surely. I'm just puzzled.

 

[Soundguy]

You can have gas cutting from excessive temps, and you can have detonation for various reasons. I know for sure those can set back ir blow ring lands off or hole pistons.

I'd be wanting to check the connecting rod, piston, piston wrist, crank bearing, and journal on that cyl that obviously hydrolocked. 7xx$ would be hard to choke down if a new crankcase vent opened in the block on that cyl after some load and rpms hit it.

 

[rbargeron]

......I would be absolutely astounded that compressed gas ever broke through a partition in a cast metal head....Surely the head gaskets would give long before that wouldn't they ? The rods too....

Soundguy covered several of the likely explanation(s) - one of the internal webs was the weak spot, and hydrolocking might have finished it off. Internal combustion engines can malfunction if conditions aren't normal (interesting reading here). It can happen in diesels if temps go way up. Detonation and/or pre-ignition describe extreme pressure pulses that can be destructive. The damage can be severe, leaving only wreckage to study. Other times many parts take the extreme load and only one is visibly broken. Others can have hidden cracks or slight buckling that show up later - or may not.

It's a lot of wrenching to get the engine out of an L48. A complete tear-down now for inspection is hard to justify. Maybe best to put a head on it so it at least runs and then keep close tabs on how it sounds & acts. An L48 is a lot of tractor and is worth replacing the block. A step at a time makes sense.

 

[IH3444]

Most likely has a bend, torqued, or twisted rod. Installing a head without a complete inspection of rods straightness, crank straightness, rod-main journal diameter measurements and surface inspections is just asking for additional major problems. Sound guy is right on the money. I still can't tell what caused the L48 to turn over on it's side, and no reason has been offer. It looks to be operating on very level ground, and parking lot space. The absolute best of luck with just the head installation. I hope it works out for the best. Even just a slightly bend in any internal engine parts will wreck havoc. bearing may have been flatten also.

 

[Oldpath05]

Is this thread is a good selling point for gas powered tractors, not to mention gas motors are a lot quieter, just thinking out loud.