Rolled my kubota 7800... Now it wont turn over. Please HELP

[dodge man]

I've been wondering about this post also.

 

[My Hoe]

I've been wondering about this post also.

Me three....

 

[Yzordderrex]

and wooden wrenches?

 

[junkyardwarrior]

A couple of thoughts-- Unless a cylinder fired when you first turned it over the rod is probably not bent. I don't think a starter ever bends a connecting rod. If the rod were bent (and you say it runs but at about 75% power level) it would make a heck of a noise.
Do let us know the outcome.

Starters will bend rods, and quite easily. As mentioned if the piston is at or near BDC, and has oil in it (even a small amount on these tiny little engines), and the operator hits the key, the inertia of the crank, rods, pistons, flywheel, everything....will help "keep it rotating" in such a way that it'll easily, and almost effortlessly, bend rod(s). I have done it, on this exact same tractor, and another (M5040HD), both times I didn't even know it. The symptoms were low power, fuel smoke, and if you kill the fuel (remove wire from stop solenoid) and crank it, you'll hear one cylinder compressing less than the others, unless all 3 or 4 are bent, and if that's the case usually it will not run at all. No other noises, no knocking, nothing. Just a little smoke and low power. The 5040 even cleared the smoke up after it got hot. Had just enough compression to run, but only when hot.

Only time I've seen one make noise with a bent rod was on an RTV1100 that had one rod bent so severely that it was contacting the cylinder wall. And yes, it was quite noisy.

Keep in mind that Kubota uses a gear reduction starter, then the large gear reduction between the starter's gear and the flywheel. So there is a LOT of torque. Most engines built within the last 10-15 years are gear reduction starters. Gone are the days when direct driven starters were around, they were weak enough that if fluid was on top of the pistons normally it didn't generate enough torque to bend the connecting rod.

 

[JWR]

OK, I take your word for all that. My experience with bent connecting rods is a Chevy V-8 and it made one heck of a noise. Also with starters that were not reduction geared. In some ways all starters (cars at least) are geared down quite a bit in that they have a tiny starter motor drive gear engaged with a large flywheel perimeter gear. We still haven't heard back from this fellow since 8/25/15 so we are kind of humming a tune to each other -- be nice if he would let us know what happened.

 

[tombodett]

OK guys sorry I kept you in suspense for so long. I ran the tractor for approximately 20 hours on three cylinders because I didn't have time to put it in the shop. I started it up on the morning I was going to take it in to the shop. I left it idling while I went and hooked up to the trailer. when I came back it had dumped a bunch of fuel into the oil pan and puked a bunch of fuel/oil out of the exhaust. I winched her on the trailer got it to the shop took all the injectors out and went and had them tested. One was stuck closed. I suspected I blew some rings so I bought a compression tester and none of the fittings wood fit in the glow plug or injector holes. So I took the head off took the oil pan off and pulled all the Pistons no broke rings. Put it all back together got it started and it ran for 10 minutes and then got a bunch of fuel in the oil in the pan again. The kubota service man said it was most likely the fuel pump was letting fuel passed into the oil. Spent another hundred dollars on a new pump after spending close to 700 on rings connecting rod bearings and a head gasket got the new pump put on tonight. I got it started up and it did the same thing. The Kubota man said The only possibility left is The injector pump. Any help would be greatly appreciated.

 

[kevin37b]

You need a new Kubota man !

 

[Leejohn]

He is right with the injector pump. You started your trouble shooting from the wrong end. You want to do the easy stuff first, send the pump out and have it rebuilt don't buy a new one.

 

[JWR]

You need a new Kubota man !

I agree. Get a second opinion ! I do not understand how a fuel pump puts fuel in an oil pan no matter what is wrong with it. My advice is do not do anything with the injection pump until someone gives you a credible explanation as to how it could put fuel in your oil pan.

 

[Leejohn]

A manual fuel pump has a diaphragm and it springs a leak fuel goes into the crankcase, also the injection pump has seals and if one goes bad the same thing.