When is Reverse Forward?

[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.