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The fire dept that I worked for as a mechanic had a 6-71 powered pumper that got run backwards a few times. It never ran away that I know of and when I did an inframe I detected no damage from this. The way it happened was when it was being backed into the bay after a run and the driver would have his foot on the brake treadle instead of the throttle. Letting out the clutch while thinking that they were adding throttle till the engine would stop and the frame and driveline would spin the engine backwards. I'd get a call in the middle of the night and sit in bed and explain it to them why smoke poured out the air cleaner. I'd have them crank it up again and see if it built oil pressure and sounded ok. They did say once that to stop it they dumped the clutch and the truck shot forward with the transmission in reverse...imagine that!!! You aint lived until you're sitting on top of an 8v53 in a boat and the govenor locks up and the engine runs away. We suspected that the govenor was worn out and the engine rolled badly at idle. I had a mechanic apprentice watching the tach and I turned the buffer screw a 1/4 turn when it took off like a banshee. I reached under my leg and tripped the air shut down. The whole thing took less than 10 seconds. Then I realized that the engine wasn't the only thing that took off. When I looked up the apprentice was gone, in fact he was at least 100 yards away up the hill. He said that he took off when the tach needle hit the back of the peg. I still haven't figured out how he got off that boat so fast. I yanked the govenor off and found that it was just totally worn out. Another govenor fixed the problem and the engine ran great. BTW, don't use a dry chemical fire extiguisher either. I had to CO2 a cat 3208 that was in an accident. It was in a garbage truck that rear ended another truck and trapped the driver by the legs in the cab. The engine was running wide open with the allison in gear and the brakes locked up. I worked on that engine for a good 5 minutes before resorting to the co2. I removed the fuel filters, the fire company had already cut the battery cables and the alternator was knocked off by the wreck which should have killed the engine by the shut down cylinder loosing power.
That driver was so happy when the engine finally quit and they got him out without serious injuries. That day started off bad as I found out first thing in the morning that a gas engined rescue unit had been fueled with diesel. I worked all morning getting that cleaned up, new plugs, filters, and pumping out the tank. The no 1 unit was out on a call and we were running this one as a back up and the call came in just as I finished so I followed it to the scene to make sure that it was going to run ok. I didn't know that I'd be working on that 3208. CaptRon
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