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Run Away Diesel - Blown Engine

4.2K views 7 replies 4 participants last post by  Melonhead1102  
#1 ·
I recently had my Duramax with under 100,000 miles on it "run away". Ignition key was turned off and engine continued to accelerate. Mechanic was on site and was able to smother the intake, but not before engine was blown. If anyone else has had the same issue, kindly respond as all other posts disappear quickly. A serious situation, not sure what would have happened if engine intake was not smothered. Engine was racing wide open, extremely load and a ton of smoke. Replacing engine now, but concerned same issue could reoccur.
 
#2 ·
From a previous post.....A run away diesel is when a failure of some kind has caused the crank case oil to be substituted has the motors fuel. What this does is make the motor have no governor since the pump or ecm is no longer controlling the fueling process. Also the the motor will eventually lock up do to lack of oil because it burned itself dry. The cause of a run away diesel can be many things. Pump failure, turbo seals failing. I read some were on the web about a duramax that ran away. The crank case was extremely over filled with oil and some how was pulled through the PVC into the intake. The only sure way to stop a run away diesel is to cut the air supply. Shutting of the pump with a manual shut off will not stop a run away since the injection pump is not suppling the fuel. This is why pretty much all diesel pulling trucks and tractors have a manual shut off for the turbos.
 
#3 ·
Sometimes mechanics that do not know diesels will spray cleaner in the intake, and that can cause a run-away engine. Or as mentioned above, engine oil can be sucked into the engine. Diesels do not have a air butterfly like gas engines to control the air and engine speed. Engine speed is controlled by injecting fuel in the cylinders.

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#5 ·
Moved to LMM
 
#7 ·
When you disable the egr but leave the cooler in place the cooler tends to catch a lot of the oil moving through the system. Under normal conditions the egr would open frequently and blow the oil out, but disabling it and leaving it there could cause trouble if the oil level in the cooler got high enough to be sucked into the engine.