Oil & Fuel Diesel running backwards

[Dan_Ives]

Has anyone heard of a diesel motor running backwards? My John Deere 4700 HST. Has done it four times with only 30 hrs. on the clock. Just before the motor stalls out, it will start running backwards. The drive pedals do not work,oil light comes on & the engine smokes like crazy. Then I shut the key off & restart it & it runs fine. When the oil light comes on..that's the part that worries me. Has one else had this problem or heard of this? I'll be talking to my dealer about this.

Dan

 

[Caretaker]

Dan,

I'd definitely talk to the dealer about that problem - It's my understanding that modern diesels generally won't run backwards. I'd suggest also that when it does that, you shut it down asap to prevent any damage that might occur.

 

[Anonymous Poster]

yes i have heard of it,and its hapend to me.you did stall ti but relived the load just in time for compretion to force piston down in a revese motion and fire the fuel.macks can do this quite easy.the injection pump will still deliver fuel even backwards. No oil presser because oil pump is runing backwards also. the tractor is fine you just have to stop lugging it to the stall point. The only diesiel that might not run backwards is electronic injection,and i'm not sure of that. Smoke out the air cleaner,diffrent sound, and no oil pressure are all signs to shut down imeditley.But it's best just not to lugg the tractor to that point,because lugging it that far is not doing it any favors.

 

[Kubbruce]

Dan,
It is possible for a mechanical injection pump to run backwards. It is best to change the air filter afterwards before restarting it because the inside of the air filter is full of exhaust. Upon restart it all gets sucked through your cylinders. This is full of soot which is not good for the rings and cylinders.
Hope that helps....Bruce

 

[Dan_Ives]

Thanks for the input on my problem of motor running backwards. I think why I'm stalling it so much is when it starts lugging down and I let off the forward pedal the tractor want's to keep going for another cupple feet. It only does it in middle and low range. High range whin I let off the peddal it stops right now. I have a John Deere 4700 HST and it's going bact to the dealer Monday. The dealer called John Deere and they said they have had some problems with this and they were going to try something different with my tractor.When and if they get this fixed I will post it in case anybody else has had this problem.

Dan

 

[jdkid]

Hi ya
yep i have heard of it and seen it happen i have also heard of tractors catching fire from it happing (backfire in to the aircleaner)i have also heard years ago (many many years ago) the lanz bulldog only had forward gears and to back back ya stoped it and on the last bang ya opened the fuel up spining the motor backwards
catch ya
JD Kid

 

[JATO_RaT]

My New Holland 2120 did it to me twice. Very little power, exhaust sucks and intake blows. It happens as you describe , just prior to stall out.

 

[Dan_Ives]

I have had two kubotas a 245 DT and L2550 for a total of 19 years and never had one run backwards. The new John Deere 4700 HST has 30 hours on it and has done it 4 times. The thing that worries me is the oil light is on. One time for over one minute. When I start lugging the motor a little and let off the fwd drive pedal it still wants to keep going for a couple more feet. Just enough to stall the motor or get it running in reverse. I wish I would have bought the PowrReverser trans

Dan

 

[jinman]

Dan, You surely have my sympathy /w3tcompact/icons/frown.gif and thanks for bringing this problem up. I had no idea this was a consideration for diesel tractors./w3tcompact/icons/shocked.gif I have a NH TC45D and its foot-pedal action is the same as you describe (It continues to lug down to stall after you get to a certain point.). I just think that is the nature of the mechanics of a hydro transmission. However, I have never had my engine run backwards. You'd think that there would be a reverse rotation detector which would shut off the fuel the same as when you cut off the ignition. Oh well.../w3tcompact/icons/crazy.gif. Anyhow, I figure you have more to worry about on the intake side of your engine rather than worry about the oil pressure. Not being under load, these engines could run a long time without doing any damage to the bearing surfaces. Hot exhaust coming out the intake is another thing completely./w3tcompact/icons/shocked.gif. Those plastic parts are not designed for exhaust heat. Of course, the reverse rotation of the gear train is also questionable as to its <font color=green>benefit</font color=green>. Good luck with getting this problem fixed. I'd hate to think you had to give up the good things about hydros to solve this problem./w3tcompact/icons/mad.gif

JimI

 

[JATO_RaT]

I'm a little confused here. Why would you let it continue to run? Its obvious right away its running backwards, no power, odd sounding etc. Why not just shut it off and restart, that is what I did both times on my New Holland machine. By the way the NH 2120 was a gear 12F/12R transmission. On my tractor it happens only when I lug it down almost to the point of stalling. It is probably inherent in the particular diesel design, in this case of the JD, it would be Yanmar, with my New Holland, it was the Shiburahehe diesel (kinda weak diesel for the size of the tractor I might add). It did not concern me since it only happened twice and if I wanted to duplicate it I could not. Its more likely a coincidence in your case and you may go many hours before it happens again. At any rate, the solution is very easy, keep the RPM's up and when, if it does it again, turn it off and restart, pretty simple. Rat...