Diesel "Runaways" and other failures to stop
I read a bit on one of the other threads about diesel engines running the wrong way, and using the oil as fuel (and not stopping until it destroyed itself). So I thought I would bring up the issue in general.
Gas (and LPG, and CNG, and Alchohol) engines have spark plugs. If the plug fires, the motor runs. Turn off the key and no more spark, the engine stops.
Diesel engines do NOT have spark plugs. When the air is compressed it gets hot - add a little fuel in one way or another, and it goes BOOM and the engine runs. But how does it stop running?
New engines are setup to cut the fuel when you turn off the key to stop the motor. No fuel, no more vroom.... Older engines have a "stop lever". On my Detroit 6-71T I had a T-handle on the dash - pull it and it went to the fuel system and manually shut down the fuel.
On a GMC bus I was working on, the fuel stop lever was so corroded it could not be pulled. Before trying to get it to start, I made sure I could get it to STOP.
One evening, on my Detroit equipped rig, I pulled the stop handle after backing into my parking place (10 pm in a nice suburban neighborhood, and my big rumbling motor really annoying the wife....) and gave the handle a pull.... and it came all the way out of the dash.
For about 10 minutes I crawled around the engine compartment trying to find where this cable went.... enough time to wake up the spouse, and get told off soundly (something about a very early class tomorrow). So I drove off again to the supermarket parking lot to figure it out. In the dark I never did find the attachment that had come loose, but did determine I could un-attach the 8 inch flexible pipe from the air cleaner into the turbocharger, and shut it off by putting my hand over the pipe (or sticking my arm inside - I was 4 FEET from the turbo intake). At idle, it wasn't bad. I'd hate to have to try that if the engine was running wide open.
So..... if you have a diesel, figure out what you would do if it would not shut off.... BEFORE it happens. Maybe know where the tools are, or have a phone book you can set over the throttle body intake, or a plunger that can plug things up.....
Just my two cents... or three (this was long).
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