Old man has balls of steel...

[RED-85-Z51]

fast forward to the 1:45 mark and hang on...

detroit 4-71 in gmc 650 running away start after the 30 years - YouTube

[Yerf Dog]

:willy:

[Sea Six]

Ok, for those of us who are non-mechanically inclined, what got sucked into the intake, and why did it rev up to nine bajillion rpm's?

[carlton_fritz]

It's alive!!!

[mrvette]

I didn't catch anything got sucked into the intake but the throttle blade was definitely stuck open for some reason, if something got wedged in there, that would certainly do it.....:dance::lol::lol:

[Kerrmudgeon]

I remember that from a couple of years ago. Pretty damn smokey in that garage. :ack:

[Bucwheat]

Don't know why they didn't turn the ignition off .

[JMS32935]

Ok, for those of us who are non-mechanically inclined, what got sucked into the intake, and why did it rev up to nine bajillion rpm's?
It's an old-style diesel engine, which doesn't have a throttle (or an ignition either). Power is solely controlled by the amount of fuel injected into the cylinders. Trouble is, leaking valve guides or leaking piston rings can let lubricating oil into the cylinders, and that adds to the available fuel. In case of a bad enough leak of lubricating oil, the engine can theoretically rev-up and run-away like that. Apparently that video is a fine example of that actually happening.

Only way to stop an engine in that situation is to choke off the airflow. Kid tries to do that with a rag at first, but he panics and runs away. He says the rag got sucked into the engine, but video shows he actually dropped it in his panic. Old guy blocks air with the 2x4, and then uses another rag to finish the job.

[Sea Six]

It's an old-style diesel engine, which doesn't have a throttle (or an ignition either). Power is solely controlled by the amount of fuel injected into the cylinders. Trouble is, leaking valve guides or leaking piston rings can let lubricating oil into the cylinders, and that adds to the available fuel. In case of a bad enough leak of lubricating oil, the engine can theoretically rev-up and run-away like that. Apparently that video is a fine example of that actually happening.

Only way to stop an engine in that situation is to choke off the airflow. Kid tries to do that with a rag at first, but he panics and runs away. He says the rag got sucked into the engine, but video shows he actually dropped it in his panic. Old guy blocks air with the 2x4, and then uses another rag to finish the job.

Oh.

[RED-85-Z51]

In this case, its a supercharged 2 stroke GMC diesel, no throttle blades, no turbo...engine speed is controlled by a governor and fuel control like any diesel engine.

This particular runaway is caused by a stuck fuel plate, its dumping 100% flow into the cylinders, there is no ignition, there is no way to shut it off besides stopping fuel flow, or stopping air flow.

The trick is, sometimes on a tired engine if you block off the intake, it will suck oil past the the rings, and simply burn that, at which point you need to go far away, as it will run non stop until it runs out of oil...

On Turbo Diesels, if the turbo breaks a shaft or blows a seal and allows oil into the engine, it will runaway and you cant stop it no matter what....

[boracayjohnny]

In this case, its a supercharged 2 stroke GMC diesel, no throttle blades, no turbo...engine speed is controlled by a governor and fuel control like any diesel engine.

This particular runaway is caused by a stuck fuel plate, its dumping 100% flow into the cylinders, there is no ignition, there is no way to shut it off besides stopping fuel flow, or stopping air flow.

The trick is, sometimes on a tired engine if you block off the intake, it will suck oil past the the rings, and simply burn that, at which point you need to go far away, as it will run non stop until it runs out of oil...

On Turbo Diesels, if the turbo breaks a shaft or blows a seal and allows oil into the engine, it will runaway and you cant stop it no matter what....

I always learn something engine wise from you. :seasix:

[Fasglas]

It's true a runaway diesel will happily burn it's own lube oil, there is NO way it will run without air. That's what the real mechanic used the ragball for. Choked off the air supply.

Vintage GM diesels, 238, 318, etc., were so prone to runaway, vehicles so equipped had an "Emergency Shutdown" control which blocked the air supply as simply turning off the key, (fuel) would not stop the engine.

It should be noted that under certain conditions, the engine could and WOULD run backwards, which was not good either. Emergency shutdown was useful here, too.

Ah, those were the days...

[syf350]

Ah, those were the days...

All in the Family Theme Song - YouTube