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Gas engines generally wont runaway because they have throttle plates or something like that to control the airflow. No air flow...no combustion. Diesels generally do not have throttle plates so just closing them to stop a runaway probably isn't going to happen.
Diesel engines runaway for 2 reasons. Either the fuel control is stuck at full flow OR the engine is drawing fuel from another source. The real scary runaway engines were the old Detroit Diesel 2 stroke engines. They were fed by a nice big super charger and the injector flow control (the rack) was tempermental when it was adjusted. If the "rack" was stuck in the full flow position the only limiting factor to engine speed was the amount of air delivered to it...oh wait...it has a supercharger... When one of these ran away you had a couple of seconds to catch it or else. Our SOP was to always have a pair of vice grips and a bungie cord on the rack to hold it at idle on start up.
A cummins doesnt have a rack to stick. The chances of all the mechanical and electrical stars aligning to cause a runaway from fuel are very very slim.
In practicality the only way a cummins could runaway is from an external fule supply like oil in the pressure side of the turbo.
I have have seen runaways from blown turbo seals or turbo seal oil leaks BUT usually they are more of a no stop condition instead of a runaway. The amount of fuel (motor oil) that can be mixed with the pressurized air is limited,the air fuel mixture is far from precise, and the ignition timing is way off.
Bottom line is don't panic. Unless you are parked next to a leaking gas well, in which case you should run very fast, just stop the air flow any way you can. I contend that breaking the boost line somewher between the pressure side of the turbo and the intake will kill the motor because this will disrupt to fuel(motor oil) and air mixture from being sucked into the intake.
I contend that breaking the boost line somewher between the pressure side of the turbo and the intake will kill the motor because this will disrupt to fuel(motor oil) and air mixture from being sucked into the intake.
Pocket knife and cut the boot open.
Mopar1973Man -=- AKA: Michael Nelson
2002 Dodge Ram 2500 - Cummins Turbo Diesel - 5 Speed 4WD
1996 Dodge Ram 1500 - 5.9L V8 Magnum - Automatic 4WD
Last edited by Mopar1973Man; 12-28-2012 at 04:47 PM.
I was watching that clip a few days ago and I can't believe that engine held together. I was expecting a big bang to happen.
Am I the only one who knows everything?
01 3500 Dually Q.CAB, Quad Adr.,pulse, 4" straight stainless exhaust, air dog FP 150 fuel preporator, half inch draw straw and fuel lines.Rancho 5000 shocks rear, 9 way adjustable up front, 3.55 rear end.DIY built DTT trans, triple disc low stall Goerand tc,billet flex plate and input shaft, DTT shift kit, Holset HX40W 60/65/16 turbo(stock turbo propping the door open)125hp DAP injectors pushing on the pistons, BHAF and more to come
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