Diesel Runaway

Anybody ever have a diesel runaway? I did yesterday. Boy, that will make your heart pump! Diagnosing a worn out, 380K mile, 6.0 Powerstroke yesterday with a stalling complaint and low injection control pressure code. Was increasing rpm checking ICP pressure, noticed the rpm started to fluctuate a few hundred rpm around 3500, then all the sudden the turbo cut loose and cranked the tach around to 5K! If it had been outside, I'd have let it go and enjoyed the show, but it was in a tight bay in the shop and I was worried about shrapnel and/or fire, so popped the air cleaner open and fed it a fire extinguisher till it bogged and quit. Customer wasn't too put about, he almost sounded relieved he didn't have to shovel money in it anymore.

Had one do it at work. International semi with an international engine. Mechanic got the fuel shut of and it started sucking the oil out of the pan. Ran wide open till it locked up.it wasn't in the yard, it was at a red light at the corner. Only a hundred yards from the building straight line, but about 1/4 mile around the 8 foot fence. Emptied the extinguisher into the air cleaner and it just slowed it down for a minute or two.

when I was working for a M F dealer he took a job hauling a combine from a barn to an insurance yard. It had been involved in an accident on the highway and not run for some time, I don't know how long. When it started it went to full speed, nowever fast that is on a diesel J D. I had a pair of pliers and unhooked the fuel line going to toe filters , but by the time it ran out of fuel the exhaust manifold was glowing red. We later unhooked the breather intake and drove it on and off the truck by smothering the engine for air to control the speed. I actually wanted to run for my life as I thot it would come apart and I didn't want to play catch with a blowing engine.

All you can do is shut down the air at the intake to stop a runaway diesel.

They say you havent heard a runaway until you have had a 2 stroke jimmy get away on you?

We had a well used Michigan loader with a 3-71 where I used to work it runaway at least once a day,just flip the emergency stop.

Cut an inter-cooler boot because it can do several things. It will cut boost pressure lowering power, if the turbo is feeding oil to the engine that should stop too, then it also gives a path to spray a fire extinguisher into the engine if needed.

6.0 and 6.4 runaways aren't too common but they should be left to take care of themselves. I've not seen much of any shrapnel to be worried about other than a hole in the pan and a lot of oil everywhere.

Had a little Mercedes marine diesel run away in my friend's sailboat. Those engines use a throttle plate and manifold vacuum to operate the governor. He was changing out an injector, and was wondering if maybe there was carbon in the injector hole. I said if he cranked it over it should blow out any carbon from the empty injector hole. He did, and the engine fired up instantly (something it NEVER did). What we hadn't taken into account is he had removed the intake manifold, and now there was no vacuum to operate the governor. The little Mercedes SCREAMED. He closed the valve at the fuel tank (which he had to reach around the runaway engine to do), but it still took a minute or two before the engine died. He feared we'd destroyed it, but that engine ran another fifteen years until the boat sunk in a hurricane.

My dad had a D7 Cat run away, although I wasn't there to see it happen. He had just overhauled it and wasn't happy with how it was running, so he started fiddling with the injector rack while it was running. The rack came loose and all four injectors screwed full-on. That Cat, which normally ran around 1100 rpm, spun up to (according to the witnesses) about 7000. We normally killed the engine by putting it in gear and dumping the clutch, but that just instantly blew out the clutch. They didn't have any luck choking of the air cleaner, and there was no fuel shutoff valve (at least one that worked). They eventually pinched off the fuel line (about 1/2 inch) with Vise Grips. I helped tear down that engine, and it was trashed: Push rods all bent, broken lifters, one broken piston. Dad eventually found an old irrigation pump engine that was identical to the original and repowered it. That D7 is still running today, about 50 years later.

seen a v8 driptroit run away in collage once. It was neat and scary at the same time, I hid behind a combine!. The guys working on it stuck a phone book on the intake but it sucked in and someone use the fire hose to kill it.

I was present when a Detroit 8V-71 ran away. My wife's step father and a friend were just finishing up a major job on it and started it to test it. It went immediately to full throttle. He pulled the fuel shut-off but by then it was burning crankcase oil. He pulled the air shut-off and the cable pulled out. He got it smothered by stuffing a heavy overcoat into the intake.

Skip ahead to about 2 minutes for the action- ''Holy Crap!''
Shes a little runaway

NOT on that particular engine but Ive experienced it myself and it was scary. In the days when I was in trucking those Two Cycle Detroit diesels experienced it (OMG loud screaming smoking lol) and had that big manual emergency lever to shut off the air if it happened.......One engine I had that ran away was a VW Rabbit Diesel and wowwwwwwww did it scream rev up and smoke lol Of course it will stop when it runs out of oil or blows up grrrrrrrrrrrrrr

Been there done that like many others here

John T

Never experienced one personally but a few years back a young farmer in the same county as I live in was working on a John Deere tractor, something along the lines of 4020, had a runaway. He couldn't get it shut down but must of kept trying as his funeral was a few days later when the flywheel blew apart! Very sad situation. I hope to never experience have one!!

I had an 1981 diesel Rabbit truck that would also runaway when you got it up to speed. That overhead cam splashed so much oil around at high RPMs that the PCV system would suck it up, feed it into the intake manifold and away youd go!

It was like a poor mans cruise control- just merge onto the X-way, throttle up and let nature take its course. You kept it under semi-control by weaving through traffic and using the brakes. If the engine got below 3000 RPM, the spell was broken and you were back to boring ''manual'' driving mode.

VW eventually came out with a tent-like baffle you put under the valve cover and over the camshaft to direct the oil downward and ruined all the fun.

My dad spent many years hauling petroleum products. Most deliveries were gravity unload but occasionally they would have to pump the load off , often into tanks to facilitate gravity loading . He said when pumping in hot humid weather you had to be careful as the fumes would often get pulled into the truck intake and you could hear the rpms increase. One time he nearly had a runaway but stopped it by throwing a coat over the air cleaner. This was in the good old days before vapor recovery was required.

Yes let a 71 series Detroit get away from you and you will find out why they call them a screaming jimmy.
Best this they did for those motors was put emergency stop on them.

My BIL left his D7 on bottom land and couldn't get to it before it was sitting under water. A few month later he had it drug up to higher ground and it set no telling how long. Was going to sell it for scrap. I offered to try and get it running. Finally got the pony freed up and got it to run. Then tried getting the big engine going. Finally got it to crank and had fuel coming out the stack along with everything else one can imagine. It cranked up and started really taking off. I panic and tried shutting it down by putting it in gear and throwing the clutch in. It started rolling up dirt then almost slowed down but the clutch started slipping. Then I remembered the decompressor and got it to stop. But not before it ran over one of his hay rings. It was fun straighten that back out.

My Father was a GM US Navy Technician in WWII and later a GM Truck and Coach engineer after the war.

He told me about a time in the Philippinies when the Navy engine room sailors were abandoning the engine room of a craft that he was on when one of the 6-71 engines in a quad set was running away at dock when the engines were not geared together during maintenance.

He ran into the engine room and choked it out before it failed by stuffing a pile of shop rags into the blower inlet.

Injestion of sea water and/or condensation into the oil in the oil bath air cleaners had raised the oil level in the cups enough that the engine was drawing air cleaner oil into the air inlet causing it to run away. Such was not uncommon at the time due to inadequate maintenance.

Brings back memories.
Del Shannon

> Then I remembered the decompressor and got it to stop.

When my dad oversped his D7, they tried the decompression lever, but it was stuck from lack of use.

I saw that happen once when I was deployed to Taiwan in 1958.

We had two big diesel generators powering the mess tent. One evening during evening chow one of them ran away, simply increased rpm until it was screaming and the whole engine blew up. The whole mess tent was full of guys eating chow, but everyone just sat there and watched. Nobody was about to go out there and try to do anything.

No idea what caused it.

This was the first D7 I ever walked up to. Had to free everything up. Used a piece of firewood and a sledge hammer to free up the pony. Had a guy that worked for me there that day. He was going to show me how the start the pony. Having to stand on the track to crank it. The pony back fired. He went one way and his cap went the other.

only had to remove the air.

I worked at a GMC dealer out of high school,everytime they ran the rack on a Detroit it would go over center and run away. They all had emergency shut offs on the intake.

YES, takes about a week to have solid bowel movements again! Very dangerous.