Bent connecting rods?

[Sid Post]

My friend has an older Kubota UTV (think it's an RTV900) with a 23hp motor with about 500 hours total time. My friend was in low gear at a high RPM pulling a single section drag behind it on his gravel driveway. I have used the same drag with his UTV and find it pulls pretty easy so, not a really high load factor or stress on the motor.

He was smoothing his driveway when it came to a hard dead stop (totally locked up). Prior to that, there was no sign of any trouble or issues of any concern.

After taking it into the dealer for service, they pulled it apart and found two bent connecting rods! What causes this? Is it a known issue with the Kubota diesel engines? If the motor was out of time badly from a slipped or broken timing chain, I would expect bent or broken valves.

The good news is the block, cylinders, pistons, etc. are fine with no damage. Apparently the only damaged parts are the two of the connecting rods. I haven't spoken directly to the dealer working on his UTV so, it is possible something has been lost in a secondhand report but, I'm curious if there is anything I need to watch for with my two tractors that might be related to my friend's issue.

TIA,
Sid

 

[Roadworthy]

If the dealer will talk to you about it the thing to do would be get the information first hand from the mechanic who fixed it. I can probably also give you an idea what happened. I wouldn't rely on second hand information.

 

[hagrid]

Its a puzzler for sure but I think we can rule out timing chain slip/jump.

 

[SDT]

My friend has an older Kubota UTV (think it's an RTV900) with a 23hp motor with about 500 hours total time. My friend was in low gear at a high RPM pulling a single section drag behind it on his gravel driveway. I have used the same drag with his UTV and find it pulls pretty easy so, not a really high load factor or stress on the motor.

He was smoothing his driveway when it came to a hard dead stop (totally locked up). Prior to that, there was no sign of any trouble or issues of any concern.

After taking it into the dealer for service, they pulled it apart and found two bent connecting rods! What causes this? Is it a known issue with the Kubota diesel engines? If the motor was out of time badly from a slipped or broken timing chain, I would expect bent or broken valves.

The good news is the block, cylinders, pistons, etc. are fine with no damage. Apparently the only damaged parts are the two of the connecting rods. I haven't spoken directly to the dealer working on his UTV so, it is possible something has been lost in a secondhand report but, I'm curious if there is anything I need to watch for with my two tractors that might be related to my friend's issue.

TIA,
Sid

Probably more to this story.

Bent connecting rods on CUTS/SCUTs are usually caused by water ingestion.

SDT

 

[D2Cat]

Or using starting fluid!

 

[North Idaho Wolfman]

Something doesn't add up.
You would have to seize the engine with water , oil , diesel or some other foreign matter in order to bend rods while running.
You could bend the rods like D2cat stated use starting fluid on it.

I'm wondering if the seizing was not the motor at all and was some other component of the machine, like the drivetrain failing.
Owner takes it in, and when they pulled the motor down they could only find bent rods from previous unrelated damage.
I wouldn't be too surprised if he gets it back and there is some other issue affecting it.

 

[fruitcakesa]

Something doesn't add up.
You would have to seize the engine with water , oil , diesel or some other foreign matter in order to bend rods while running.
You could bend the rods like D2cat stated use starting fluid on it.

I'm wondering if the seizing was not the motor at all and was some other component of the machine, like the drivetrain failing.
Owner takes it in, and when they pulled the motor down they could only find bent rods from previous unrelated damage.
I wouldn't be too surprised if he gets it back and there is some other issue affecting it.

My 97 y.o. father was mowing his lawn on his Craftsman LT3000 when he ran up on a rock and stopped.
He tried to restart it but it would not crank at all, only a click.
He called me to help get it out.
I managed to wrestle it off the rock and out into his garage.
When I tried turn the motor over by hand, it only spun a few degrees and then stopped..
Dismantling showed that the conrod had broken into a dozen pieces.
My only thought was that he hit the rock with the drive pulley which stopped the motor instantly and shattered the rod.

 

[BigG]

I hope I get to p!ss off my son when I hit a rock with my mower at 97. You just gota love him.

 

[SidecarFlip]

Like Paul Harvey used to say.. There is more to the story.

 

[BruceP]

Using 'starting fluid' on a modern diesel engine often causes mechanical damage. The engine may not fail immediately... but the engine fails months or years later.

Infact, it has been said that a good mechanic, after tearing engine down. is able to visually see the damage on piston crowns and combustion chamber.

 

[kkk]

I just got mine back from the dealer.
07 ish RTV900

The problem with these machines is a .02 cent fix.
The sensor thats Supposed to turn the fan on is a POS.

If your working it slow and steady like pulling a drag or Aerator in my case ,they overheat.
Then the head gasket goes.

Brand new sensor and head gasket in mine with 600 hrs. First trip out ..No Fan.
Pull the wire off the sensor...its on top of engine towards the front..Ground It.
Now your fan is always on with the key......No more overheating.
I'm guessing His got water in it at some point hence the bent rods.

 

[fruitcakesa]

I hope I get to p!ss off my son when I hit a rock with my mower at 97. You just gota love him.

That Craftsman was about the sixth tractor he has either rolled and wrecked, destroyed the deck trying to cut rocks [he is near blind and deaf] or some other combination of perils.
I got my old T1400 hst from him after it quit and he replaced it with another tractor.
It had a bad magneto or the like. $150 later I had great little K lawn tractor.
Being the PO'd son occasionally has its perks

 

[Tx Jim]

Fruitcake you should be glad that your Dad is still alive & well at 97. My Dad passed when he was only 75.

 

[fruitcakesa]

Fruitcake you should be glad that your Dad is still alive & well at 97. My Dad passed when he was only 75.

I am glad he is still alive and kicking as is my 97 yo mother. They are both doing well for such advanced age too.

 

[Lil Foot]

You both should be glad, my Dad died at 41.

 

[SidecarFlip]

Plus 1. Both mine have passed long ago

 

[Sid Post]

Or using starting fluid!

Starting fluid is a hard no with a diesel if you want it to do something other than hand grenade. Even WD-40 hits pistons really hard.

 

[Sid Post]

Something doesn't add up.
You would have to seize the engine with water , oil , diesel or some other foreign matter in order to bend rods while running.
You could bend the rods like D2cat stated use starting fluid on it.

I'm wondering if the seizing was not the motor at all and was some other component of the machine, like the drivetrain failing.
Owner takes it in, and when they pulled the motor down they could only find bent rods from previous unrelated damage.
I wouldn't be too surprised if he gets it back and there is some other issue affecting it.

With the hydrostatic transmission, would it really lock up hard enough to bend connecting rods? I guess it is possible though with a brief pulse of high pressure for some reason.

 

[SDT]

With the hydrostatic transmission, would it really lock up hard enough to bend connecting rods? I guess it is possible though with a brief pulse of high pressure for some reason.

Not a chance.

SDT

 

[kkk]

Ran mine today......No load....Fan on full time.....gage still goes nearly halfway up to hot.

Do Not rely on the fan sensor...Bypass it.

My guess ..His was hot..May or may not have noticed...Shut it off...Puked water in 2 cyl. .
Hit starter and..Bingo...bent rods.

I'm thinking I need to have radiator gutted.....It was flushed with recent 1 hour ago Head gasket job but is clearly still acting up with fan full on.

Thermostat Perhaps...IDK...will put in a call to my Kubota tech.

This is a costly issue....I ain't made of money.