What makes a diesel engine continue to run ( dieseling) after being shut off.

[TboneJerry]

I have a 1984 Ford 1910 diesel tractor. Why would it continue to run after I close the throttle completely. It didn't do this till lately.

 

[timcasbolt]

A diesel runs until you stop the fuel. If it's still running, it's still getting fuel. On my Kubota I pull out a knob to shut off the fuel. The key shuts off the electricity. Does yours work like that?

 

[Alvin 41]

I have a 1984 Ford 1910 diesel tractor. Why would it continue to run after I close the throttle completely. It didn't do this till lately.

Some badly worn diesels when very hot will run away on oil from the crankcase .

 

[Hemmjo]

Search U Tube for “runaway diesel”. Some wild videos.

Maybe your fuel shutoff is worn and cannot stop the flow completely.

Any source that can supply oil for combustion will keep it running. In modern Diesel engines one source is bad seals in the turbocharger. That often causes the engine to blowup.

 

[used red MN]

I have a 1984 Ford 1910 diesel tractor. Why would it continue to run after I close the throttle completely. It didn't do this till lately.

Hello Tbone.. welcome to YT! The parts catalog shows a fuel stop knob for engine shut down. Maybe this doesn’t apply to all units produced. If it does have a stop knob and you haven’t used it that is the problem. The idle on pump was set low enough that it didn’t provide enough fuel to support sufficient ignition in the cylinders so the engine would stop. Now the throttle linkage or something in the pump is worn and not pulling the governor actuator back enough to close the fuel delivery valve sufficiently to kill the engine. The fuel stop knob should override this and make the engine stop.

 

[Mcrafty1]

If the tractor has electric shut of and it isn't shutting of the tractor, the electric shutoff has malfunctioned. It's an electric solenoid usually in, on or near the fuel pump that's the problem.
If it's a mechanical shutoff, the linkage between the hand throttle and the pump is worn enough that it isn't closing the fuel off anymore.

 

[showcrop]

wear in the throttle linkage, find the adjustment, and adjust the slack out.

 

[sandcastle1]

still feeding fuel, compression and heat cause the diesel motor to run, gas motor needs spark from the plugs to run.

 

[Dean]

I have a 1984 Ford 1910 diesel tractor. Why would it continue to run after I close the throttle completely. It didn't do this till lately.

Either the shut down system is not working properly, or the engine is getting fuel from another source, e.g., oil bath air cleaner, crankcase, etc.

 

[JIM MN]

What Hemmjo said? On a turbocharged charged tractor, bad turbine shaft seal leaking oil into the intake air side, can cause this problem. Seen on tractors with a lot of hours?

 

[Jim Hanson]

Don't believe your tractor has a turbo so that's out.....if it's mechanical shut off find where the cable goes to the pump and try to pull it a bit farther , may just needa bit of adjustment

 

[Caryc]

Some badly worn diesels when very hot will run away on oil from the crankcase .

The only way to stop them then is to shut off the air supply. While working on a Mic 8 engine in Vietnam, we started one bank of engines and they took off screaming at full RPM. there were three of us down in that engine room and I swear that all three of us went up that ladder and out that small hatch at the same time. There happened to be an E6 with us at the time and he jumped down there with a fire extinguisher and sprayed it into the intakes and that stopped them.

 

[TboneJerry]

Thanks for all the reply's. Since this a very old and worn tractor (with no turbo), I'm not gonna mess with the fuel control system. It's running good enough for now. Last thing I want to do is open up a can of worms. I checked and the linkage and it has no binding or slack in it. Instead I'll just start shutting the fuel off at the tank. Funny thing is it only started doing this about two months after I purchased it.

One more question : It has glow plugs. To start it, I have to turn the ignition on and wait about a minute or two before starting to allow the glow plugs to warm up (as usual with an older diesel engine). My question is, since I leave the ignition on while driving it. Are the glow plugs still on and glowing while the ignition is still on? Seems like that would wear them out prematurely. I know it will still run if I turn off the ignition because it is a diesel and has no need for a spark to ignite the fuel mixture after it's running. Problem is if I turn the ignition off, that will also turn off the heat gauge which I don't want to do. Is this normal with diesels? Do the glow plugs stay on the whole time the ignition is on? I used to be an auto mechanic and know how to work on gas engines. But this is the first diesel engine I have ever worked on.

Again thanks for all the help, Jerry.

 

[Fritz Maurer]

You're better off stalling it at low idle than you are shutting the fuel off. Shutting off the fuel will create a sustained vacuum in the fuel system, which in itself is not a bad thing, but if the system is not vacuum-tight , it will admit air upstream of the pump and the system will end up air-locked which will cause trouble next time you go to start it.

 

[TboneJerry]

By stalling it, are you referring to stop the air flow or letting out the clutch while still in gear?

 

[showcrop]

What Fritz posted

 

[Mnethercutt]

By stalling it, are you referring to stop the air flow or letting out the clutch while still in gear?

Jerry,

A couple of things you need to think through before you decide to just keep 'running it as is'...

If, as some have suggested, you are burning oil and that's what is allowing it to continue to run, you need to address that issue before you start having more issues. Does the tractor use oil? Are you regularly checking the oil level? If it is using oil then you need to address that ASAP...

As far as a better way to shut off the machine, I would highly encourage you to attempt to fix the linkage issue rather than using an alternative shutdown method. As others have said, just turning off the flow at the shutoff valve is not a viable option for a diesel. You will get air (or more precisely a vacuum) in the system that will cause problems down the road. That shutoff valve is there so you can change the filters without spilling diesel everywhere. Others have suggested stalling it; while they don't specify my assumption is they are referring to dumping the clutch. If it were my machine I would avoid this.

I would highly encourage you to try and fix the issue. See if you can disconnect the linkage at the injection pump and move the fuel controls by hand to shut off the tractor; that should tell you if its a linkage issue or an internal issue.

If you've made up your mind and don't want to mess with it, the safest option is to cut off the air flow by covering the air inlet with a piece of plywood or other hard, flat surface.

 

[Hemmjo]

I am sure that Tbone meant letting the clutch out, high gear, brake on.

You need to consider it did not do this before. It is doing it now. Something is going bad, it is not going to suddenly get better. It is going to get worse, perhaps sudden and catastrophic.

Better to find the issue early rather than after total failure.

 

[used red MN]

One more question : It has glow plugs. To start it, I have to turn the ignition on and wait about a minute or two before starting to allow the glow plugs to warm up (as usual with an older diesel engine). My question is, since I leave the ignition on while driving it. Are the glow plugs still on and glowing while the ignition is still on? Seems like that would wear them out prematurely.

Unless someone has modified your tractor you are not activating the glow plugs by just turning on the ignition switch. Again if in stock configuration the glow plugs do activate while the starter is cranking the motor. To activate the glow plug preheat you turn the key counter clockwise and hold it. Then watch the hole in the “Cold Start Aid” indicator to the right of the tachometer.(see picture) Above 50F or so when it starts showing a dull glow of the coil in it you turn the switch over to the start position. The colder it is the brighter the glow of the coil has to show for it to start well.
Originally your tractor had a stop knob, should be on the lower part of the dash or directly under it on the side of the tractor the injection pump is on. Link to engine stop parts diagram

 

[Fritz Maurer]

By stalling it, are you referring to stop the air flow or letting out the clutch while still in gear?

Engage the clutch while in top gear.