[Diy_efi] Runaway turbo diesel?
WSCowell at aol.com
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...
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