4. LUBRICATION SYSTEM MXU 550EXi/MXU500i Dowel Pins Remove a bolt and then remove the oil pump holder. Remove the two dowel pins. Remove the two bolts and then remove the oil pump. Holder Oil Pump INSPECTION Oil pump drive chain guide Inspect the drive chain slipper surface of the drive chain guide for wear or damage. Slipper Surface INSTALLATION Install the oil pump. Make sure the pump shaft rotates freely and arrow on the oil pump is upside. Oil Pump 4-6