Join Date: Jul 2011
Location: Alvin, Texas
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Re: My Horror Story
If your engine is running away and cutting off the fuel does not stop it, it is getting fuel some where else!
Most likely is source of uncontrolled fuel is crank case oil. One engine with an oil bath air filter would run away if the oiler (AKA idgit!) over filled the oil bath air filter.
If the engine is blowing oil out of the crank case vent back into the intake, check to make certain that the crank case is not over filled. You may even have the wrong dip stick in that thing. If the level is OK on the stick, see if you can find another engine like yours and compare them.
Another possibility is the baffle in the crank case vent line may by improperly assembled, parts missing or? Check the parts you have against the manual to make sure yours is put together right.
I have also seen diesels runaway when other fuel is introduced with the air. Natural gas can do it, even paint fumes if concentrated enough. If you are squirting MMO into the intake to loosen stuck valves or fogging oil preparing for storage, know that a diesel will treat anything flammable as fuel if it can get into the cylinder and will burn.
My diesel experience is with heavy equipment and some smaller stationary engines, generators, pumps and such. Over filling the crankcase can lead to a runaway that is only stopped by restricting the air as you say. Some engines have a cable operated emergency shutdown damper on the air intake for just this problem. I have shutdown smaller engines as you did by putting my hand over the intake. Gosh that thing can suck can't it!
Last edited by OPossumTX; 05-20-2013 at 08:20 PM.