[Diy_efi] Runaway turbo diesel?

WSCowell at aol.com WSCowell
Wed Sep 12 19:01:32 UTC 2007

When I was serving in Germany in 1979 as an engineering officer in the  
British Army, we had an interesting blow-up with a tank engine at our  Workshop 
unit in Soest.
It was an L60, used to power the Chieftain battle tank.  The L60 has 6  
cylinders side by side in line, and 2 crankshafts at opposite ends of the  
cylinders driving 6 opposed pairs of pistons a la Junkers Jumo aero  engine.  The 
engine is multi-fuel, and usually ran on diesel.  It had  a massive Roots type 
scavenge blower strapped to the side of the  crankcase.
This engine was on test but the exhaust wasn't coupled up properly and  
consequently the exhaust gases were getting into the test cell, which was a  closed 
room at the end of the engine repair shop.  The blower intake wasn't  coupled 
up to a source of clean intake air (sloppy mistake No.2!!) and breathed  the 
ambient air inside the test cell.
All was well until an oil seal failed, whereupon oil mist started to appear  
in the exhaust and, yes, you've guessed, sucked back into the intake.
The revs started to rise, the crew panicked and shut down the fuel supply  
but it was too late, the engine went into runaway and the revs went through the  
roof as the engine digested its crankcase oil supply.  The entire test cell  
filled with a combustible oil mist and it became a giant combustion  chamber.
After about 30 seconds stoichiometric mixture was reached, and the entire  
chamber (room) blew.  It took out the internal walls, every window down the  
repair shop and cracked both end walls of the repair shop building from floor to  
ceiling!  By this time everyone had legged it so no-one was hurt, but the  
Board of Inquiry had a field day.
Never a dull moment in the military...
Will C


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