Balloons Belong at Birthday Parties Not in Transmissions
I rebuilt a 454 GM engine that went into a motorhome application. It ran well, and no problems immediately appeared. But later on, it was towed in with a main bearing failure in the thrust area. I gave the customer another engine, and a month later it came back with the same problem. Upon further investigation, I discovered that the torque convertor had ballooned, causing the engine and also transmission problems. It seems that it was severely overloaded. The motorhome owner was a flea market vendor and was towing a trailer that was way too heavy for his setup. Lesson: If you build an engine with an automatic transmission for severe-duty, nitrous, supercharged or just high-horsepower, be certain that the owner installs an anti-balloon torque convertor. Hopefully, you will avoid the same problem after reading this. – Note: Crankshaft grinders are used to getting “defective” crankshafts returned to them with thrust flanges wiped out due to this type of problem. – Engine Pro Technical Committee

Lee Johnson
Pro Performance
Denver, CO
October, 2013