Maintenance - Drive belts Drive belts The 300 TDI engine uses a 'serpentine' type drive belt, which drives all the ancilliaries except for the air conditioning compressor. An automatic belt tensioner keeps the belt at the correct tension, thereby eliminating the need to manually check the belt tension. The belt and all pulleys should be examined regularly for any damage, deterioration or fouling with mud, grit or chaff etc. Under normal use the belt should be changed every 1,200 hrs or every 2yrs but in adverse conditions it may need changing at 600hrs or less. Before checking or adjusting any drive belt, turn off the battery isolator switch to prevent the engine from being started Replacing drive belt 1. Disconnect both hydraulic and fan drive shafts. 2. Fit a 15mm ring spanner on to the tensioning pulley centre bolt (A above right) and turn anti-clockwise to release tension. 3. Remove belt and release tension gently. 4. Check all pulley grooves for wear and cleanliness. 5. Turn tensioner anti-clockwise again and fit new belt. 6. Re-fit drive shafts (see notes on page 32)   Air conditioning compressor belt To tension the belt correctly an accurate torque wrench will be required. Slacken the 3 bolts (1) securing the tensioner Apply a clockwise torque of 35Nm to the square drive (2) of the tensioner and tighten the bolts to 25Nm                     < 31 >