Hagen Brothers farms,Goodrich ND | frmrzdotr - 4/26/2009 12:48
Apparently you've never heard of internal EGR. On some Tier 3 engines the exhaust valve opens at the bottom of the intake stroke to allow some exhaust back into the cylinder. This happens before the intake valve closes. This reduces the normally over-oxygenated diesel combustion process and reduces NOx. Unfortunately it also increases heat rejection to engine coolant, but the EPA doesn't mind that.
Turbos don't have to spin to fail. even a frequent oscillation back/forth on dry bearings can begin to form tiny flat spots on bearings, eventually causing a failure. The sock or duct tape on an exhaust stack is the best way to assure that turbo rotor movement is ZERO, or at least minimized. Like someone else said, cheap insurance.
Would you post the brand and model of a tier 3 engine that uses that internal EGR system ? I would like to read up on it to better understand the air flow through them. Should be interesting reading.
Like I said in my other post, the turbo builders /rebuilders were not worried about windmilling the turbo on an older non emissions engine of just a few years ago, but that may well be different with the EGR equipped machines.
They always did recommended covering the exhaust to keep road trash out of the turbo and engines, now saving the turbo may be another factor if the EGR system allows enough air flow through or around the engines to spin the turbo. TIA.
Edited by Jon Hagen 4/25/2009 18:03
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Covering exhaust pipe
