Unplug the negative battery cable on the battery and position the engine at TDC at the compression stroke of cylinder number 1. Take out the drivebelts, crankshaft pulley and
Timing Belt. Clamp the camshaft sprocker still with Mazda tool no. 49 H012 010 or similar one, then unscrew the sprocket bolt, being careful not to break or ruin the sprocket by the special composite material. Slide the sprocket off the camshaft and take the old oil seal off the shaft using a screwdriver or any pick tool, taking care not to cut or scratch the camshaft or the seal bore. Wipe down the surfaces prior to installing the new seal and put a light coat of oil onto the surfaces of the seal and lightly drive the seal in with a seal driver or with a large socket with a slightly smaller outside diameter than the seal. Fit the sprocket, with the notch in the sprocket over the key in the camshaft and the R or L mark in the 12 o'clock position and also ensure that the timing mark on the sprocket is matched with its corresponding mark on the
Cylinder Head. Lastly, re-assemble the other parts in the same order in which they were disassembled.