L3400 running backwards !

   / L3400 running backwards ! #1  

Chilly807

Elite Member
Joined
Sep 13, 2009
Messages
3,225
Location
Nova Scotia
Tractor
Kubota L3400DT
Some of you are going to find this hard to believe, but it happened.

Today I was using a log winch to pull some alders out, roots and all. The tractor (09 L3400) was idling with the PTO engaged running the winch. It doesn't usually take a lot of power to pull alders. One bunch was harder than the rest to pull, ended up getting lodged between 2 trees. By the time I noticed, it had dragged the rpm down to just about the stall point before I let the winch rope go to unload the engine. It stayed running, although the idle sounded slightly lower than normal.

Being stubborn, I pulled the winch rope to re-engage the winch and try pulling the alders again, figuring they might have loosened the first time. This time, the winch did nothing, the cable didn't even move. Thinking that was odd, since there had been no expensive-sounding crunch or snap, I looked to be sure the PTO was still engaged and turning, which it was. I didn't realize it was turning the wrong way. I pulled the winch rope again, still nothing.

By this time, I was scratching my head, saying "What the hel* is going on here??" I looked at the tach to see what the rpm was, since it still sounded slow. It was low all right, it was reading zero. Nada. Nothing... then I noticed that the oil pressure warning light was on, and the light bulb in my head went on too.. No rpm showing, winch didn't work, no oil pressure... "The **** thing is running backwards!" The crank must have stopped for a split second, then compression pushed it back the other way and it fired in the wrong rotation, just like an old make-and-break engine.

Luckily, the key shut it off right away, total run time (backwards) was probably about 30 seconds. No big deal at idle, likely little to no bearing damage. I restarted the engine, everything acted normal. Shut it down, pulled the air filter, which although smelling distinctly like exhaust since it had been acting like a muffler, was clean and not damaged.

The bird's nest in the winch took me about an hour to get untangled (never turn one of those the wrong way, trust me on this!)

I called my dealer and told them what happened, just for their information. They said they'd heard of some older Deere's doing the same thing, but this was the first Kubota they'd ever heard of doing it. Leave it to me to be the one to discover it was possible!

Lucky I didn't walk back to free up the alder clump and leave the engine idling, no oil pressure for 5-10 minutes would have been enough to do serious damage.

Other than the slow idle and the oil pressure light, there were no indications of a problem, no rattling or poor idle, it was smooth but slow.

Interesting day, but not one I'd recommend trying at home!

Next time I'll run the engine at a higher speed, more pulling power and more room to drop before it gets to the stall point.

Sean
 
   / L3400 running backwards ! #2  
Your right the engine ran out of power and compression kicked it back and made it run backwards.

I know a guy who had that happen on a New Holland. He is one of those people that use a rough cut at 1200 rpms. He was mowing a steep hill that a goat would not climb and ran it out of power and the engine ran backwards.
 
   / L3400 running backwards ! #3  
running backwards is not a big deal.you just bumped the heack out of the motor pulling that log thus causing the motor to run backwards.an it ran fine when you cranked it again.
 
   / L3400 running backwards ! #5  
im a bit amazed. Im trying to think of what type of fuel injection system would let this happen?
 
   / L3400 running backwards ! #6  
Wow, Sean, that is a first that I have heard of for a 'bota. Man, that can't be a "good thing", bound to have put a few "hours" on the bearings and other lubricated parts.

James K0UA
 
   / L3400 running backwards ! #7  
I don't do anything at idle. It's just not a place the engine was designed to operate at while doing work.
 
   / L3400 running backwards ! #9  
"im a bit amazed. Im trying to think of what type of fuel injection system would let this happen?"

Mechanical.

With EFI the crankshaft position sensor would be going the wrong way so the CPU could shut off the fuel.
 

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