4 strokes do run backwards.

[Mhannink]

well believe it or not but four stroke engines run backwards. my buddy and i where 4wheeling this weekend and my buddy was in 4 low 1st gear with 4. 10s and was trying to stall it. well the truck started to stall and he let off at that point and the truck started driving backwards. took us a second to figure it out but we then relized that the engine was indeed running backwards.

 

[n7gxz]

Yes I can say that they do. Had my Cat D2 do it to me when I was loading it on the trailer. Not a pretty sight when it starts running backwards and sending the exhaust back through an oil bath air cleaner.



Kevin

 

[OKish]

heck, most if not all engines will run backwards. especially if they are real hot and you shut them down at a high rpm. we had an old datsun pickup that would diesel backwards for about 30 seconds or so. was an interesting sight to say the least, i know the 6bt will run backwards to seen it in a bread truck.

 

[AH64ID]

I would say it depends on if the injector is in the cylinder or not... You couldn't get a carbed rig to do it... .

 

[Greenleaf]

John Deere had a problem with that. You'd pull the engine down and it would stop and restart the opposite direction.

 

[JLEONARD]

John Deere had a problem with that. You'd pull the engine down and it would stop and restart the opposite direction.

So after you backed thru the garage door did the wife buy that excuse???:-laf

 

[PToombs]

I did it with a Mack with a 237 once. Let the clutch out and it went backwards. Reset gear, same thing! I shut it off, restarted, and all was good! :-laf

 

[jwgary]

What kind of bearing damage does that do? I know that if our 8000 hp air compressor shuts down without being unloaded the pressurized air in the inter- and aftercoolers will cause the machines to run backwards. This causes all kind of problems since the oil flow for the bearings assumes that the shafts always turn in one direction. Turning the other way causes oil starvation and you can wipe out a bearing fairly quickly.

 

[Mhannink]

I would say it depends on if the injector is in the cylinder or not... You couldn't get a carbed rig to do it... .

well no gasseres are not prone to this problem the same way diesel is. becasue of carbs or the the injectors typicaly being outside the cylinder.

What kind of bearing damage does that do? I know that if our 8000 hp air compressor shuts down without being unloaded the pressurized air in the inter- and aftercoolers will cause the machines to run backwards. This causes all kind of problems since the oil flow for the bearings assumes that the shafts always turn in one direction. Turning the other way causes oil starvation and you can wipe out a bearing fairly quickly.

yes if it ran for some time it would do damage to the bearings however the oil film on the bearings will prevent any damage if only run for a few seconds as is the case in my situation

 

[OKish]

You couldn't get a carbed rig to do it... .

not true, happens all the time especially on carbed engines, shut them down hot and at a high idle... . shuts the ignition off, fuel still being pulled into cylinder and into hot exhaust manifold... runs backwards when it sucks the fuel vapor back through the exhaust manifold and diesels backwards.

 

[donnier]

Had a friend that snapped the crank shaft on his import truck.

When it started to "diesel" he thought it was fun to turn the key back on when it was running backwards.

He did it one afternoon and snapped the crank.

They will do it if the circumstances are right.

 

[Mhannink]

not true, happens all the time especially on carbed engines, shut them down hot and at a high idle... . shuts the ignition off, fuel still being pulled into cylinder and into hot exhaust manifold... runs backwards when it sucks the fuel vapor back through the exhaust manifold and diesels backwards.

yeah but it wont stay running such as a diesel and probably not very well. a diesel will run backwards rather well and as is such on the 2strokes run away on you

 

[AH64ID]

not true, happens all the time especially on carbed engines, shut them down hot and at a high idle... . shuts the ignition off, fuel still being pulled into cylinder and into hot exhaust manifold... runs backwards when it sucks the fuel vapor back through the exhaust manifold and diesels backwards.

Actually when a carbed rig diesels it still turn the correct direction, it doesn't fully shut off and typically some carbon in the cylinder is hot enough to aide in combustion.

 

[Dieselnut59]

I have stalled my '96 and had it run backwards before, right as I "gouged" on the accelerator, so it even revved up! HUGE plume of smoke through the air intake and out from under the hood! Truck took off backwards in first gear. Weird feeling!

I also have had my Polaris "kick back" and run backwards. Totally weird feeling on an ATV! I think it did damage the timing chain tensioner, as the chain broke a short while later and caused major damage.

I have stalled my Kubota lawnmower several times and it kicked back and began running backwards. It will not spin the blades in reverse and the hydro unit will not move it when oil is flowing the wrong way! LOL

 

[KDHannink]

meant to do it

I once had to load my hay truck with a hay squeeze made out of some odd ball forklift. To change direction you stepped on the other side of the throttle and the engine would stop, then run the other way. Was a pretty weird feeling, hard to get used to. That was years ago, I have no idea the make of the forklift, or if the engine was 2 or 4 stroke. A buddy says that old-school diesels in boats and ships would run backwards on purpose too. Those were 2 strokes I think though.

Saw a guy stall a 6v92 in a hay squeeze and got it running backwards, poured smoke from the air intake, had to put the forks into the ground in high range reverse to stop it. Was pretty scary in a dry hay barn!

 

[EKlem]

The boat engines you are referring to are known as direct reversing. They were pretty common in tugs and larger ships until reliable transmissions and controllable pitch propellers came out. The reason for them was that they had no way to reliable couple and decouple the propeller shaft from the engine so rather than doing that, they simply kept them coupled and had the engine change directions. They were big old air start engines that had an engineer to run them. The captain and engineer generally could not speak to each other so it was done through a system of bells. The captain and engineer would get to the point where they could anticipate each other really well. When the captain would ring for a change in direction, the engineer would shut off the fuel, wait for the engine to almost be stopped, throw a lever that was linked to everything that had to be reversed, then open up the starting air and it would start in the new direction.

 

[Dieselnut59]

I once had to load my hay truck with a hay squeeze made out of some odd ball forklift. To change direction you stepped on the other side of the throttle and the engine would stop, then run the other way. Was a pretty weird feeling, hard to get used to. That was years ago, I have no idea the make of the forklift, or if the engine was 2 or 4 stroke. A buddy says that old-school diesels in boats and ships would run backwards on purpose too. Those were 2 strokes I think though.

Saw a guy stall a 6v92 in a hay squeeze and got it running backwards, poured smoke from the air intake, had to put the forks into the ground in high range reverse to stop it. Was pretty scary in a dry hay barn!

Are you sure it was the engine changing directions on that lift?

Hyster forklifts use a "Monotrol" pedal with two arrows on it. You step on the arrow in the direction you want to go and mash the pedal down to accelerate. It is done through the transmission though.

Baker (now Linde) forklifts have hydrostat transmissions where you push down on a separate pedal to go forward or reverse.

On a forklift, I do not see how the engine could reverse, as the hydraulic pump (for lifting, tilting, etc) will only work in one direction.

 

[KDHannink]

I could be wrong, that was a few years ago. I just remember stepping on the other side of the pedal and it would slowly come to a stop then go the other way, without touching any levers. I guess the engine fan, water pump, hydraulics, and other accessories would have to be designed for that, unlikely they were.

 

[Cattletrkr]

I drove dump truck for a guy who warned me it was a possibility in one of his trucks. I think it had a CAT 3208.