what makes a detroit run away?

I have a little jd 440 crawler, it has a detroit 2 cyl dsl engine. I started it one evening to smash some metal w/ the bucket and as soon as it lit the r's went nuts, I droped the throttle to the off spot and nothing changed. It stated sounding somewhat serious and i had to think quick so I took off my new leater riding jacket and opened the air cleaner and shoved it down. between that and running the bucket all the way up and back and holding it there i finally got it to die.
Since then I turned it over w the throttle all the down and it was gonna lite so I back off and dont quite know what to do.

wild detroit

Worn or disconnected throttle linkage could cause this. If it has a cable for linkage, that could be seized and holding at WOT.

Have you foud anything out further about this wil detroit?

Most likely you have a stuck injector. This will hold the entire rack in the position the injector is stuck in. Very common in Detroit. Could be the governor itself also holding the rack open.They can run wild for other reasons but I would check these things first.

i have a 353 detroit in my bantam dragline. while digging in some blue clay,digging a pond,i almost stalled the engine, darn thing started running wide open in reverse.had to jump out.run to the back an flip the lever shutting off air to the blower.when i restarted it, it smoked for about fifteen minuets,then it ran perfect

Yep, bad idea to stall a Detroit. That's prime time to make one run backwards. :yup

detroit

Gene Nolen said:

Most likely you have a stuck injector. This will hold the entire rack in the position the injector is stuck in. Very common in Detroit. Could be the governor itself also holding the rack open.They can run wild for other reasons but I would check these things first.

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This is good advise, remove the valve cover and see if the rack is stuck/froze/not free (its the round rod/pipe about 1" in dia, with all the thingees attached to it) The rod has two linkages that fit into the injector fuel rods. If the rack is stiff/froze find out what injector has it locked up, just look at the movement on the injector plunger and the stuck one wont be moving. Locate the injector and take a metal drift/stock/etc and rest it on top of the thingee that the rocker arm presses down. Just tap the drift with a small hammer and the injector should free up, it may take several times. This works 80% of the time, this is not a repair, its a temporary fix to get you out of a bad situation. The injector will have to be changed, you can pour all the WD40 on it as you want, but it wont help. Let us know what you find out and we will help you remove and install a new one. Just dont turn too many screws and bolts, unless you know how to set the rack back up.

I have seen the flyweights in the governor go bad and the bushing/bearing freeze up, but normally its the injector

Keep us posted

Another reason some diesel engines will run away is an oil leak into the intake. Some of the cat truck engines have been known to do the same thing when the oil seal in the turbo begins to leak on the intake side. I am not too familier with the detroit blower setups but I would guess the same thing is possible. If an injector were stuck it should still have shut down when you closed the throttle as the shut off would stop fuel from getting to said injector. My grandma's 3406 cat did the same thing to her while she was driving down the road a few years ago and the only way she could stop was to hit nuetral, the engine blew before she even came to a stop. As you found out cutting off the air supply is the only way you can shut it down as the oil becomes the fuel source and it cant be stopped. As I said I am not familier with detroits but I would inspect any seal between oil and the intake. Good luck and let us know how it turns out.

It has been a long time since I've worked on one, but if I remember right, when you shutdown a Detroit the rack goes to full throttle. On the older models, if an injector sticks and you start the motor it will go to full throttle. The old versions had 2 screws on each injector lever and the linkage was pretty much solid. Newer models went to a spring loaded lever with only 1 screw and you should be able to over-ride a stuck injector. I've always told people if they have a detroit that has set for much more than 6 months, better pull the valve cover and check. It's a pain but better than blowing it up.

chuck jacobs said:

i have a 353 detroit in my bantam dragline. while digging in some blue clay,digging a pond,i almost stalled the engine, darn thing started running wide open in reverse.had to jump out.run to the back an flip the lever shutting off air to the blower.when i restarted it, it smoked for about fifteen minuets,then it ran perfect

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I can't quite get my head around this , if the engine was running in reverse . Wouldn't the blower also be running backwards and exhausting through the intake/air filter ? How would closing the over rev safety flap stop the engine ? Wouldn't the pressurized air , force the flap open ? Not arguing , just wondering .

That is what happens,the exhaust exits through the air cleaner and the exhaust pipe becomes the intake.
It can make a mess if it runs long enough through the old oil bath air cleaners.
Any diesel engine is subject to running in reverse,not just Detroits.Just think,we have 18 speeds in reverse..LOL.Ron G

I have read that blower seals can get leaking, especially after using the air flap to shut the engine down. Also read that one must use a straight grade oil(#30 or #40) with the correct designation, and that water in the fuel can cause injectors to stick. There is also an air box drain that should be checked to make sure it's open.

I have not had any experience with troubleshooting on these engines, but have rebuilt a few, they are quite interesting to work on. Attached a picture of a 4-53 engine block showing the air box opening. Phil

Phil said:

I have read that blower seals can get leaking, especially after using the air flap to shut the engine down. Also read that one must use a straight grade oil(#30 or #40) with the correct designation, and that water in the fuel can cause injectors to stick. There is also an air box drain that should be checked to make sure it's open.

I have not had any experience with troubleshooting on these engines, but have rebuilt a few, they are quite interesting to work on. Attached a picture of a 4-53 engine block showing the air box opening. Phil

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That is one screwed up block guess somebody thought it would run better if they painted it cat yellow

I like the topic title What makes a Detroit runaway?

Easy the sound of a Cummins, coming down the road..

LOL I went to a large air compressor school years ago. The focused on the Detriot and Mercedes engines that came in the machine. In the middle of the class the instructor stated that there was no such thing as a runaway engine! There were quite a few older seasoned mechanics in the class and as you could imagine that statement made quite a stir. After a few minutes of discussion from the mechanics the instructed laughed and said that there were over speeding engines which caused ran away mechanics! That got quite a laugh!

I am no expert but wouldn't a broken governor spring let it run away also ?

What makes a detroit run away?

I would say he has bad parents. No body ever blames the parents any more

Another Trick

One time I heard about a guy that had a Detroit run-off on him and he shut it down spraying a fire extinguiser into the air intake. { It must have caught it's oil when it took off }

A sad thing to see, but shows a Detroit on a full throttle death. Go to YouTube, Type in Detroit Diesel Meltdown in the search bar.
Don't know if this engine had cooling water to it, It looked it caught it's oil though.

detroit

Koehringman said:

One time I heard about a guy that had a Detroit run-off on him and he shut it down spraying a fire extinguiser into the air intake. { It must have caught it's oil when it took off }

A sad thing to see, but shows a Detroit on a full throttle death. Go to YouTube, Type in Detroit Diesel Meltdown in the search bar.
Don't know if this engine had cooling water to it, It looked it caught it's oil though.

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Trust me the old 71 and 53 engines would and will run away. I have been there and done that. The first time it happened to me, I worked at Cat and I rebuilt a 4-71 detroit on a generator, the weekend mechanic put the governor on and set the governor and the rack and said it was ready for the dyno testing. I put in in the dyno and hit the starter and away it went, it was turning past 3000 rpm when I looked at it (it was a 1900 rpm engine) , then it caught a second wind and started climbing. This all happened in less than a minute and Im trying to get the outside air intake off, so I can choke it off. I did get it cut off, but the second wind was it picking up oil out of the base and burning it. Dont ask me how but I was always told that this was the reason for the second wind and possible boom next. Me and my helper had to take a nerve pill after that one, come to find out the other mechanic had set the governor wrong and I think the flyweights were on the wrong side of the shaft stop. This was when I started putting vise grips on the rack, on a first time start up.
I did have one other time on a marine engine 6-71. I was in the milatary and the night shift put a new governor on and something must have been wrong with it, engine cranked up and started past 3000 and I was doing this and that and nothing helped, so I grabbed a fire ext and unloaded it in the blower screen. It did stop it, but we had to take the engine out and rebuild it. I wish I had something to put over the intake screen, but there was nothing

OK my finger is getting sore from telling war stories, if you didnt remember anything I said, remember Detroits 71& 53 series will run a way. These are different animals that we see now a days, so mostly it takes an old timer like me to tell these stories. I do like this engines, they will run forever, regardless of how you treat them. I have one in an old Drott 40 excavator, I use for a yard machine, you cant kill it

Good Luck and Happy New Year to everyone

Willis, I really enjoying your stories, keep them coming.

I was working in a pit once, and got to know the chap running one of the Koehring 505 cable shovels. He was strange one. When I saw the Harper Diesel truck there one day, I asked what happened to the 6-71. Apparently the fuel truck filled the tank with gasoline instead. With excitement he described how she "barked like a wild dog" and had all kinds of power, before her life ended a few minutes later. Phil