The LDT-465 that ran backwards

Cleveland Iron · Aug 10, 2010

Grey Shadow and I were maneuvering our deuce in a tight area. He pulled forward and wacked a tree in first gear (compound low). The truck stalled and restarted.

Shadow started exclaiming that the gate was gone; he couldn't find reverse. The truck would only go forward in that gear.

In the mean time there was lots of smoke around the truck's hood. I was getting concerned. I pulled the air intake cap and got a face full of multifuel exhaust. Then I remembered a story about a deuce that had run backwards...

I climbed to the tip of the "J" pipe and felt it sucking in air. Confirmed, the engine was running backwards!

I yelled to shut it down. Grey Shadow complied immediately killing the engine. Then he restarted it, we checked things out and all seemed OK. No damage. *whew*

The reason engine had been running in reverse was the bounce back from the tree with the truck still in first gear compound low. It had stalled and restarted the engine backwards. So it CAN happen.

rorybellows · Aug 10, 2010

oh yeah it happens. not really good for it. hope he didnt damage anything. if he didnt he got lucky. kinda neat though

4trans · Aug 10, 2010

My dad did it in the army(at aberdeen doing testing on all the new goodies) and the engineers said its impossible, and he had one do it by accident. Then he figured out how to get it to do it and he proved to them that it was possible to do on purpose. The engineers also said the trailer would never flip but they were not the ones that had to unravel safety chains from around pintle by hand when it rolled multiple times

steelandcanvas · Aug 10, 2010

There has been another thread on this, if fact it happened to me in Germany on my assigned vehicle. Weird to see exhaust coming out the air intake bonnet. It is entirely possible.

rlwm211 · Aug 11, 2010

Definitely not good and the oiling system is not functional unless I am mistaken about that.

This is definitely a thing that makes one think a bit!!!!!!

I will stow that one away in the memory bank.,...hope I can find it when I need it!
:mrgreen:

RL

Floridianson · Aug 11, 2010

rlwm211 said:
Definitely not good and the oiling system is not functional unless I am mistaken about that.

This is definitely a thing that makes one think a bit!!!!!!

I will stow that one away in the memory bank.,...hope I can find it when I need it!

RL

NOT MISTAKEN Get the motor stoped as fast as you can one way or the outher.

Floridianson · Aug 11, 2010

[QUOTE and all seemed OK. No damage. *whew*.[/QUOTE]

How did the bearings look!
No oil pressure at gage, Tac not working and goes forward in reverse. You did not have to get out of the truck?

wsucougarx · Aug 11, 2010

Yikes, didn't know this could happen...now I do

Varyag · Aug 11, 2010

I have heard of M60 tanks doing this too.

ncpamlicoboy · Aug 11, 2010

I am new to this sight and have learned amazing amounts about the old iron we all love. Also am not at all familiar with deuce engines so correct me if I am wrong but from a theoretical stand point this is not possible because just a few reasons as follows: first the injection pump. “Is the injection pump on a deuce gear driven?” If that is the case even if you could get the engine spinning in reverse you would not be pumping fuel with your injection pump. Spinning the pump the wrong way would not inject fuel in to the engine. Second even if the injection pump some how could pump fuel to the injectors it would start injecting fuel on the engines (squeeze stroke also know as compression) the fuel injection would stop close to top dead center you would have had detonation way before this thus trying to push the piston back down spinning the crank the right direction again. I have heard of engines burping (back fire) but if the engine starts again it will be running in the right direction all of the smoke was probably from your burning air filter. Third if the truck is a turbo equipped truck the turbo will not work backwards the way the volute is designed it used velocity and expansion to make pressure. If exhaust went into the volute it might spin the blades but unlikely and it wouldn’t make any pressure with the turbine thus running as an N/A engine. It would be like trying to run a turbo equipped engine with out the boost pipe installed good luck blew some boots of sled pulling trucks and they never restarted (to much fuel not enough air). Again I am not trying to call anyone a liar I just feel that this is a lot of “my wife’s sisters uncles grandfather twice removed…the story get slightly bent as it gets told” if this really did happen that is amazing and it would be a very important for everyone to know. As rlwm211 said “your oiling system would be nonexistent” and that with detonation going on one would destroy there engine very fast I am a marine engineer and currently work on a ship in the Gulf of Mexico with 16,000hp. This just goes against everything I have ever learned just my 2 cents thanks for a great sight guys it is all of us banding together to keep the hobby alive.

Floridianson · Aug 11, 2010

ncpamlicoboy said:
I am new to this sight and have learned amazing

Stick around and learn more. The intank pump is running cause it's electric and supplying the IP.
Don't need turbo to run.
You a engineer or just a oiler/wiper?

mudguppy · Aug 11, 2010

it also seems to go against the principles of suck-squeeze-bang-blow. on a 4-cycle, i have a hard time understanding how this is possible.

i'll let the injection pump go, because i'm not sure how it is designed. i do know that a simple plunger/barrel system will inject fuel when run backwards.

at first thought, even if fuel is injected, it is injected after the exhaust cycle and there would be no compression stroke. however, upon closer analysis, this is not the case. rather, the compression cycle would now be the power cycle. the injection event would occur and you could have a new power cycle on the old compression cycle.

timing would have to be pretty close to TDC (mild) and/or compression would have to be very high to retain enough heat to cause combustion - the MF has both of these characteristics. obviously, timing would now be quite retarded and it is likely that the intake valve would open early, prematurely ending the power cycle.

i believe this is not possible on most 4-cycle engines because the compression ratio and injection timing would not be conducive to swapping the compression and power cycles. howver, for the MF the theory is sound.

oh, and you can run a turbo backwards - the compressor can act like a turbine and vice-versa. that's what a turbo is, anyway.

Wildchild467 · Aug 11, 2010

rlwm211 said:
Definitely not good and the oiling system is not functional unless I am mistaken about that.

I agree... oil pumps dont work backwards...and how long did they run backwards and the bearings were still ok? Then i read other threads about spin on oil filter conversions and building oil pressure fast. thats good and all, but has anybody ever damaged their engine by having it run backwards for a little while? I realize that its a rare occurance, but it does make you think about it!

FreightShaker · Aug 11, 2010

I work with a maintenance mechanic for the national guard and he has personnally seen a deuce run backwards. He said that it sounds different but will happen. He also said another soldier forgot to put oil in an engine while doing an oil change and ran the engine for 5 minutes or so. After an oil analysis was run, no metal was found. These engines must be very forgiving. This was his first hand account, not he said, she said, his cousin said.

Cleveland Iron · Aug 11, 2010

The reply from GrayShadow

All that is well and good....but I was sitting in the driver's seat. This WAS NOT a tale from Granny's brother's rotton kid. The **** thing ran backwards. No ifs, ands, buts or maybes ! :jumpin:

Reality has a bad habit of distroying scientific theorys...Sorry......

Chief_919 · Aug 11, 2010

ncpamlicoboy said:
I am new to this sight and have learned amazing amounts about the old iron we all love. Also am not at all familiar with deuce engines so correct me if I am wrong but from a theoretical stand point this is not possible because just a few reasons as follows: first the injection pump. “Is the injection pump on a deuce gear driven?” If that is the case even if you could get the engine spinning in reverse you would not be pumping fuel with your injection pump. Spinning the pump the wrong way would not inject fuel in to the engine.

The IP will pump fuel through the injector lines when turned in either direction. The lift pump is electric, so it will pump as long as it has 24V.

Second even if the injection pump some how could pump fuel to the injectors it would start injecting fuel on the engines (squeeze stroke also know as compression) the fuel injection would stop close to top dead center you would have had detonation way before this thus trying to push the piston back down spinning the crank the right direction again.

In essence, what was the compression stroke becomes the power stroke, and vice-versa.

I have heard of engines burping (back fire) but if the engine starts again it will be running in the right direction all of the smoke was probably from your burning air filter. Third if the truck is a turbo equipped truck the turbo will not work backwards the way the volute is designed it used velocity and expansion to make pressure. If exhaust went into the volute it might spin the blades but unlikely and it wouldn’t make any pressure with the turbine thus running as an N/A engine. It would be like trying to run a turbo equipped engine with out the boost pipe installed good luck blew some boots of sled pulling trucks and they never restarted (to much fuel not enough air).

The trubo will be inefficient on these, but remember these engine were designed without a turbo, and the turbo was only added to the engines later not for more power, but just to clean up the exhaust emmission. These engines will run just fine with the turbo removed.

Again I am not trying to call anyone a liar I just feel that this is a lot of “my wife’s sisters uncles grandfather twice removed…the story get slightly bent as it gets told” if this really did happen that is amazing and it would be a very important for everyone to know. As rlwm211 said “your oiling system would be nonexistent” and that with detonation going on one would destroy there engine very fast I am a marine engineer and currently work on a ship in the Gulf of Mexico with 16,000hp. This just goes against everything I have ever learned just my 2 cents thanks for a great sight guys it is all of us banding together to keep the hobby alive.

Ohh, it happens. I have seen it several times, and did it myself as well as a new PFC.

The easy starting of the hypercycle engines, as well as the unique fuel injection and combustion methods on these mean that several things one knows as rules for a standard diesel don't really apply to these multifuels.

Cleveland Iron · Aug 11, 2010

Thanks for the info FreightShaker, I did have concerns about the bearings after the event. We were taking her out for a parade and all the guages looked good and the engine sounded happy so we went.

We figure that between the time for me to stand there with the smoke blowing through the air intake and into my face, me standing there going "WTFO." then testing my backwards theory (hand on exhaust pipe) then GrayShadow finally killing the engine was in the 40 second range. ( Not bad for the clueless facing the unexpected! )

I'd heard a story about this happening, but never expected to write one.

davesgmc · Aug 11, 2010

steelandcanvas · Aug 11, 2010

Just to add a little to my previous post, as soon as I saw exhaust coming out of the air bonnet, I pulled the engine stop. I knew something wasn't right, but didn't know what. I spoke with our Maintenance Officer later that day (WO3) and he said internally, with everything just right, the MF can start backwards. I asked if I had done any damage, he asked how long did it run? A few seconds, the oil pressure gauge wasn't even registering yet. (Wouldn't show pressure anyway, the pump doesn't work backwards) He responded probably no damage was done, and instructed me to take an oil sample. Oil sample came back OK. Definetly not good for the motor, but for you doubters out there, 3 posters on this thread have actually witnessed it happening.

Recovry4x4 · Aug 11, 2010

I did the same bump, stop, start at the 07 GA Rally with crusty the dropside. I knew exactly what was going on and killed the fuel. Started it back up and been driving it ever since. I'm sure I can get it to do it again. If anyone wants to bring a title to their deuce, I'll bring my title and we'll make a title wager. Perhaps in theory, it is impossible, but reality has taught me differently. As far as oil pressure, they run for 10 to 15 seconds without oil presure on a cold start so a little while with oil already on the bearings, shouldn't do much damage.

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