Runaway diesels,a cautionary tale.....

[Carleton Hughes]

Near 15 years ago I was called by a local historical society to give an estimate on restoring an early power plant on a Long Island estate.

This consisted of a 25hp Fairbanks Morse type Y heavy oil{diesel}engine with 5 foot flywheels connected to a Westinghouse squirrel cage alternator,really neat 1920's period power plant.

It hadn't been run in 30 years so I proceeded with the usual resto,techniques.

The only really time consuming part was properly setting up the starting engine,which drove an air compressor that filled a tank to 250PSI then automatically cut the spark when that pressure was achieved.

The model Y is a 2 stroke compression ignition motor,crankcase air charging and bottom cylinder uniflow scavenging,one starts it by placing a blowtorch on the "hot bulb"atop the cylinder,levering the flywheels so they indicate 20 degrees after TDC,flipping on the fuel line after manually pumping it to 30psi.

When all this has been done you pull the lever from the air tank and with a deafening whoosh the motor should start and run under it's own power,truly an impressive sight.

I should mention now that the crank and main bearing journals are drilled and lubed from an elevated sight feed oiler.

About 2 years after I restored the motor they ran it one weekend and it destroyed itself,it kept accelerating way past it's governed speed of 600rpm,it ran so fast witnesses told me the foundations shook.

Finally it reached such a speed that the flywheels disintegrated,pieces of which were thrown through the roof,one piece was discovered a half mile away.

Fortunately no one was injured.

Here is what happened.

Time constraints would not allow me to demonstrate the motor so some handyman was asked to do it,out of sheer ignorance he removed the crankcase cover,saw it was dry AND POURED 5 GALLONS OF OIL INSIDE!!!

The crank splashed the oil which was drawn into the cylinder as fast as it could with the results I described.