Engine/Transmission (1994 - 1998) Motor ran backwards!!

[firemanmarc]

Has anyone everhad their engine run backward?? Last week while in McDonalds drivethru line mine ran backward after starting it. It was idling real low, thought I would move it out of the way. . Put it into 1st and it rolled backward, tried 2nd same thing, put in reverse and it rolled forward. . I shut it down and started it this time with a little throttle and it fired right, let out the nastiest smoke I ever smelt. Since it only did for about 20 seconds did I hurt it. It seems ok now. I will check the timing this weekend..... Thanks, marc

 

[tgordon]

That is a new one to me, I have never heard of diesels doing that. I would ask whom ever it is you get stuff from for sure, but I know they say on the old engines when breaking them loose not to turn them backwards, but then again that would not be apples to apples.



You didn't happen to look at the air filter did you, I would think that might look a little nasty.

Did you have oil pressure?

 

[fest3er]

Cool! I've only heard of 2-smokes running backward! Never 4-smokes!

Technically, the engine could have fired a little early on one cylinder which caused the engine to turn backward. The injection timing would've been real late (like 14-17 degrees ATC). But I could see it running!

I'll have to keep an eye on mine. I typically start it by touching the key *just* long enough to turn the engine; its momentum carries it through the first cylinder's compression and firing. By all rights, mine should run backward some day starting it like this.

 

[SRath]

Now THAT would be some story to give the cops and insurance company if there had been someone right on your rear bumper in the drive-through lane! You'd be getting asked to "walk this straight line" and "close your eyes and touch your finger to your nose... "



You know you couldn't get it to it again to defend yourself...

 

[RALLER]

Used to drive a GMC coe 2 stroke with air ride puilling 2 trailers. The cable shift would get sloppy, so sometimes i would find 3rd gear instead of first. Engine would kill with front bumper raised. As it droped, engine would run backwards, raising rear of tractor,killing engine, and restarting. So there i sat like on a teter-toter, going up and down. To go forward, give it some fuel at the right time and away you would go. Had to be ready with the brakes as didint want to be going backwards at a stop sign. Scared me the first time. Just something else to watch out for.

 

[BILLVO]

I have seen a few different Cat engines run backwards also in my years of wrenchin. It never hut anything in any of them either.

 

[RVPILOT]

backward running

I used to work on Mercedes Diesels back when you could work on them. i e backyard mechanic. the engine had a butterfly in the intake passage way and to my best recollection it was a safeguard to reverse running. I am not sure of this but there was a butterfly valve there. can anyone enlighten us about this? Stormy

 

[PToombs]

I drove a '66 Mack once that I got to run backwards. No oil pressure and the oil came out of the air cleaner. (oil bath type)

Last I knew, it was still running!

 

[WDaniels]

I got my 96 3500 to run backwards once. I started it and turned it off for some reason then got the brain fart to turn the key on again before the engine stopped turning and it started running backwards. Smoke out of the airfilter. Shut it off right away and started it back up like normal. That was the only time I ever did that with the 5. 9

WD

 

[cahammer]

I know that smoken monsters has done that and also his brother inlaws 97 has done it once so ya it happens just dont rev it up when it does

 

[hdm48]

I too have had engines run backwards. Mostly Macks. Now keep in mind golf carts are designed to do that. As in, when you want to go forward, it runs forward, when you want to go backwards, it runs backwards.

The only concern you would have is the oil pump is not pumping oil into the engine, but out.

Kinda wierd.

 

[TEasley]

I worked in the oil patch for 3 yrs, driving semi's and bobtails. Most of them had 2 cycle Detroits, 8V56's and 8V92's. Running backwards was usually caused by trying to get one un-stuck on a muddy well location. Jammin gears and bouncing on the clutch pedal like a trampoline. First clue was a lot of reverse gears, second was no oil pressure, and I think no tach, if you took time to look. It always happened to me at night, so never saw the air cleaner smoking. Never had to pull the emergency cut-off, just turn off key and restart. I know one night one ran probably 2-3 minutes because the drivette was out of the cab wanting to know what the hell was wrong with the truck; left it idling! Drove it back to the yard later, no apparent harm. Amazing!



Never saw a Cat or Cummins run backwards, but I'm not shocked.



Forewarned, thanks, Tom

 

[Gene Arnold]

RVPILOT,



I once owned a Mercedes 220D. If my 72 year-old brain remembers correctly, that butterfly in the intake was to prevent a run-away. I've been wrong a lot of times so I could be wrong on this too, but I don't think so.



Gene

 

[AFellows]

I had a Cat run backwards on a jobsite (trying to get un-stuck) like TEasley said. I shut it down fast and as far as I know(no longer with company), the truck is still running with over 500K on it.

 

[TEasley]

Gene; that's what it was for. I've only seen 3 runaways, but they are still imprinted. (69 yr old brain) Two were from wellhead gas in the air, and one was from leaking blower seals letting engine oil into the intake/scavenge air. All 3 were Detroits, and all survived because the drivers pulled the emergency kill, which shuts off air to the engine. The company I worked for had a standing order that if a driver or operator had to emergency kill an engine, only a shop mechanic could reset and restart it. They wanted to know why it ran away!



Didn't mean to get off the thread, but when you hear an 8V92 trying to grenade, it'll nearly make you crap yourself.



Sobering thought---our Dodges don't have emergency kills.



Tom

 

[firemanmarc]

Thank you all for the very interesting replies. . I changed my BhaF and cleaned intake out pretty good. So far so good... I went back to that McDonalds and they had I could have a Free Big Mac as long as I never go through the drivethru with it again. Got a nice chuckle out of that one. . Thank you again, Marc

 

[tgordon]

They are dong it on snomobiles to get reverse now without the trans there.



TE, at what point does a 8V92 grenade, I ran a 6V92 W/allison, and was always told to put the trans in 1st, peg throttle to floor and when it revs out all the way then shift to 2nd, how far beyond that is grenade, I missed that on the tach:-laf



Troy

 

[TEasley]

t; I don't remember for sure, but I believe the 8V92 went on the governor around 1650-1800 rpm, and I don't remember a grenade symbol on the tach either, but when one starts to run away, the governor can't stop it because it is only controlling normal fuel delivery, and the engine is running away on un-controlled fuel. Only the emergency kill will stop it. Shuts off air.



Hard to describe the sound, it's roaring and screaming at the same time, and you think it's gonna explode and the shrapnel will kill everybody. Grenade.



Hope I don't ever hear another one.



I drove a day cab Autocar with a 6V92 in it for awhile. Drove it just like you said. That engine revved so slow, you could talk on the CB waiting to upshift. Crappiest ride I ever had.

on edit: this truck had a 13 sp. Roadranger.



Tom

 

[gcorron]

Wow, I hadn't heard of this in years.



I ran a Case loader backwards, never you mind the circumstances but let's just say I was far more concerned about BVD damage!!!!! Oil blew out the Donaldson air filter and I shut it down immediately, no damage, I drove this thing for another few years. I was more concerned with getting the oil cleaned off the machine so no one could see what happened, you know, the "Never let'em see you sweat syndrome".



Think rolling backwards down hill at warp factor 8, days before any ROPS cages, and DO NOT put it in a forward gear... ... trust me on that!!



I was working at a government warehouse once, it was on the river and one of the local National Guard units worked on their landing craft there. I had gotten pretty friendly with the mechanic and would go over and eat lunch with him nearly everyday. I'm headed around the corner with my lunch bucket and here came Danny screaming around the corner yelling "RUN George". I took his advice.



Someone had moved his CO2 extinguisher that he used to halt runaways, one of the Detroits he had just rebuilt decided to take off and he had no way of stopping it.



It makes a sound you don't soon forget and one HECK of a mess!!