When is Reverse Forward?

[ctpres]

Pushed my Bota a little to hard and managed to leave a little brown spot on her wrinkled seat. Same old process, dig hole around tree-cut roots with axe-push tree down with Bota-fill hole and burn tree. Seems I was pushing her a bit to hard and maybe didn't have RPM's up enough. Anyhow when pushing tree down ,motor seemed to stall and stated making BAD sounds and smoke was comining from under hood. Pushed on reverse peddle and she went forward?? Couildn't go forward-tree in the way. Tried forward and she backed up?? Shut her down looked under hood, not real sure what I"m looking for while thoughts of hugh repair bill were running thru my head. Finally got up enough nerve to try starting again and guess what happened? A little smoke starting and everything OK. Finally figured out that there was enough spring tension in tree from pushing so that when motor stalled tree pushed Bota backwards and viola, a reverse running engine.

 

[groundcover]

I saw that happen once with a 40hp Bota with a farmi tree winch,he was flogging it hard and next thing you know it was running backwards,shut it down and 'rebooted',all was well, Note to self,don't buy tractor from that kid!

 

[jinman]

Lucky you! Nice story and demonstration of how it can happen.

 

[john_bud]

CHANGE THE OIL ---> NOW.

You stalled the engine by pushing too hard, then the compression in the cylinders spun the engine BACKWARDS and it continued to run. BACKWARDS.

What's the big deal? The OIL PUMP was also running BACKWARDS ! No oil to the crankshaft, no oil to the rods, no oil to lifters, no oil to the rocker arms, etc. No oil = big issues. $$$

What else is wrong? The HST pump was spinning backwards and sucked un-filtered oil, and had pressure where suction was expected and vice versa. Probably not a huge issue as the HST's are tough.

Any thing else? Well, since you mentioned it, yes. The exhaust manifold is the intake and the intake is the exhaust when you run backwards. You know all those plastic and rubber pieces starting with the air cleaner and going to the cast manifold? They may be melted. Check that closely. I would take them off and wipe the insides clean and feel for any burns.

That it? Uh, no. The fuel injection pump was also starved of lubricant and was also put at risk of catastrophic failure. They are generally fairly delicate devices.

Ever watch NASCAR when they spin around and go backwards? The engine is going backwards for that 1/2 second to 3 seconds. The engine is pretty much toast after that and usually billows smoke about 5 seconds after shutting down and restarting. Hopefully, you won't have ruined your engine, but you could. If you even suspect you are running backwards --> SHUT DOWN THE ENGINE. In the worst case you could wind up needing a rebuilt injection pump, engine and transmission. Seriously. It can cost you a LOT of money and it only takes a few seconds.

Cross your fingers and hope you shut down quick enough.

jb

 

[hanson1999]

i'll agree with your oil not getting where it should, but the intake/exhaust does not change, how was it running backwards with no fuel if the exhaust was changed to the intake???

 

[Billy_S]

how was it running backwards with no fuel if the exhaust was changed to the intake???

And wouldn't the fuel tank have eventually overflowed?

 

[john_bud]

i'll agree with your oil not getting where it should, but the intake/exhaust does not change, how was it running backwards with no fuel if the exhaust was changed to the intake???

Go out to your shop where you have a spare engine and rotate it by hand backwards (or use your imagination) and determine which valve is open just after the spark plug sparks. The physical orientation does not change between the camshaft and the distributor any more than it does between the camshaft and the fuel injection pump. Diesel fuel injected, piston compresses, fuel burns, open INTAKE VALVE. Guess where the hot gas goes next as that valve opens?

No, they don't run well backwards as the valve timing is all goofy. They don't normally run at all backwards.

 

[Wheatland KB]

And wouldn't the fuel tank have eventually overflowed?

We should all get some old engines and run them backwards to produce fuel. Great idea

On the serious side, Thanks for the input John Bud. Had this happened to me I doubt if these points would have crossed my mind right away.

 

[AKfish]

This is a new one for me... never expected such a thing! Interesting bit about the NASCAR cars, too.

I've heard about snow-machines with engines that will run either in forward or reverse orientation. Engine actually stops forward operation whenever you shift transmission into reverse and runs in reverse.

AKfish

 

[powerstroke444e]

lots of older 2cycle golf carts are made to run backwards in reverse.

 

[hanson1999]

my polaris sled runs backwards for reverse, hit the button, sled almost dies, then fires in reverse. of course it is a two stroke, but i never have had exhaust comin out the airbox,,,,,,,haha

maybe we have found somethin here,,,,fillin the fuel tank for free??!!!!!!

 

[john_bud]

maybe we have found somethin here,,,,fillin the fuel tank for free??!!!!!!

When you get it perfected, sign me up!

jb

Did a quick google search for some examples of backwards running engines....

"Yes a non-electronically controled diesel will run backwards. Heard of it happenening on a Mack truck when rolling back into a loading dock and the driver popped the clutch. Had it happen to me a couple times. I was a mechanic for a Caterpilliar truck engine dealership. Sometimes when you used the Jake brake quickly when there was no load on the engine it would cause the engine to run backwards on the 3406B's and C's. With a mechanical injection pump it didn't make any difference which way the enine turned it still pumped fuel. You would have no oil pressure and exhaust smoke would come out the air intake. The electronic engines have a way to tell which way the engine is spinning and will not give fuel if it is backwards."


Some other "damage" areas listed were timing belt popping off from the tensioner on the "wrong" side, and water pump not working well.

jb

 

[DanD78]

This is real easy to do on the older Detroit Diesel engines. Lug it down till it's last breath and dump the clutch. The old Putt Putt cars they used on the rail road had a reversable engine. You some how moved the timing and the engine would run in reverse.

Dan

 

[silverdollar6]

Now does he have to cut that tree down again?

 

[Stimw]

I used to drive a GMC Semi with a Detroit Diesel. It would stop and run backwards when trying to back under a heavily loaded semi trailer.
I've also seen other drivers have this happen with Detroits. It's funny when they try to back up again and it goes forward. And they thought I was crazy when I told them what happened.

 

[MJPetersen]

The old detroits did run backwards, but they are also 2 stroke diesels, but they have valves, 4 of them per cylinder, all exhaust. They do not run well backwards though, wrong injection timing, too late--ATC, and the blower is sucking air out instead of plowing it in.

I agree with John too, an oil change is in order and soon. It is not good for them to run the opposite of the intended. But now you know.

Mike

 

[MJPetersen]

i'll agree with your oil not getting where it should, but the intake/exhaust does not change, how was it running backwards with no fuel if the exhaust was changed to the intake???

On a diesel your fuel is not mixed with the air it is injected usually between 30 and 20 degrees before TDC. So, when it is spinning backwards the power stroke becomes the compression, and the compression the power, the intake and exhaust are also reversed. "The smoke was coming from under the hood"--the exhaust was coming out of the air filter housing, putting the heat of combustion into the airfilter is not good, besides as John stated, the air intake usually has lots of rubber and plastic parts.

Mike

 

[DanD78]

There is a dump truck contractor that bought two running Detroit engines out of a large boat. He needed a starter for another Detroit engine so he took one off one of the boat engines. When he fired it up the engine was running backword. Come to find out he bought a left hand and a right hand rotation enginie. I guess that was common to keep the engine torque equal?

Dan

 

[john_bud]

There is a dump truck contractor that bought two running Detroit engines out of a large boat. He needed a starter for another Detroit engine so he took one off one of the boat engines. When he fired it up the engine was running backword. Come to find out he bought a left hand and a right hand rotation enginie. I guess that was common to keep the engine torque equal?

Dan

That, but also to keep the boat going straight. If both props are going in the same direction, there is a lot of sideways force that will kick the back of the boat over. You then have to steer to offset. That wastes energy. Having counter rotating props allows them to cancel that sideways force and you steer straight.

jb

 

[carpenter383]

I've always been a gear head and have never heard of any engine running backwards. I guess you learn something new every day! The tree must have had ALOT of pressure to push the tractor backwards against the hydrostat, In my experience they will usually slide the tires before it would turn the motor.