Alternator Tensioner Pulley - FTO 2.0 V6 DE3A These are very prone to wear. To check simply rock top to bottom like a wheel bearing, any more than about a mm or 2 play and it's on it's way out. Remove belt and spin it to make 100% sure, if it's noisy change it. Exploded Diagram & Belt Layout - HERE RN-STD-51 Mitsubishi Part Number MD303884 MD359746
