CRANKSHAFT FAILURES

What NHTSA is examining

The pe was opened based on reports of failing crankshafts on heavy truck enginess and a related service letter (ps50663) issued by caterpillar.the service letter makes available a phased-in extended warranty for a replacement crankshaft, based on mileage.odi is concerned that a failed crankshaft mayresult in a disabled (stalled) 80,000 pound vehicle.odi also has concerns about vehicle control, given that the power steering pump may be disabled, in the event of an engine shut down.during the pe it was discovered that at least some of the engines may continue to operate, but with dramatically reduced power and possible adverse affects on vehicle (steering) control.odi is concerned that the engine's high failure rate will continue to increase with time in service.odi is aware that many of the engines are reaching the point of being overhauled, however, it is unknown what affect this will have on identifying potential future crankshaft failures.caterpillar has determined the root cause of the crankshaft failures to be grinder burn,whichresults in a crack at the # 1 or # 6 connecting rod fillet. This crack is not visible during a visual inspection of the crankshaft.in summary, a heavy vehicle with limited or no mobility and possibly compromised steering control is of concern to odi and more so if hazerdous materials are being transported.therefore, odi has upgraded this investigation to gain a full understanding of the safety impact on vehicle operation. Odi will be contacting…

Vehicles under investigation