To remove the secondary chain, put the engine at TDC for cylinder no.1 and unbolt the VANOS adjustment unit. Remove the timing chain tensioner plunger from the right-hand side of the engine with the aid of a nut screwing on the opposite side, and discard the sealing ring because there is a strong spring attached to it. If reusing the tensioner, push and pull the plunger a few times to expel the oil in the chamber. Insert a suitable drill bit into the trolley of the secondary chain tensioner to lock the plunger, and then remove the camshaft position sensor wheel from the exhaust camshaft sprocket and the plate spring. Thirdly, take off three intake camshaft sprocket nuts and a corrugated washer, and then the three screws of the exhaust camshaft sprocket; lift the secondary chain together with the sprockets, the friction washer and the intake camshaft splined shaft and set it in the order for assembly. Check the chain for pre-determined wear, if the sprockets are worn or the chain has too much side- way movement or making noises, change it. The sprocket teeth must be worn flat or hooked and the chain guide and tensioner contact surfaces should be worn. During installation, make certain the Number 1 piston is at Top Dead Centre (TDC) with the crankshaft locked and verify the position of the camshafts. Insert the special tool into one of the primary tensioner holes and turn the screw until it lightly comes against the tensioning rail. Through the use of the special tool or by positioning the sprockets in a manner that there are 15 chain pins within the cutouts. Place in the chain and sprockets above the camshafts, making sure it fits correctly and put the splined shaft back into the intake camshaft. Replace the corrugated washer and the retaining nuts with a torque specified on each nut dimension in the assembly. This particular exhaust sprocket screw must be tightened up to 44 inch pounds, and then it must be loosened up by turning it counter clockwise 180 degrees. There is friction washer and plate spring fitted with the F mark facing forward; there is also the exhaust camshaft position sensor wheel to be reinstated, the nuts tightened by hand. Remove the exhaust splined shaft, pinch the secondary chain tensioner plunger, unlock the pin. Twist the adjusting screw on the special tool and operate until all possible movement is eliminated. With the help of a special tool, set the splined shafts and sprockets with screw-in pins and nuts gradually and evenly tightening to the max. torque stated. Turn the crankshaft two full revolutions and check the position of the camshafts in relation to the locking tools so that the timing is correct. Last of all, take out the centering tool and refit the VANOS adjustment unit. For the primary chain unscrew the splined shaft and the sleeve with the exhaust camshaft sprocket together with the secondary timing chain, secondary chain tensioner and the three screwed pins in the exhaust sprocket. Let the timing chain be free and slide and then take off the timing chain cover so that you note the way it passes around the crankshaft sprocket to get detached from the later. Delocate the tensioner rail and chain guide after twisting the cline retainer clips. That is for installation; ensure that Number 1 piston is at TDC, engage the chain with the crankshaft sprocket, and re-fit the chain guide and tensioner rail with correct routing. Line up the timing arrow on the exhaust camshaft sprocket with the upper edge of the cylinder head; fit the sprocket; replace the timing chain cover. Slide the special tool to the tensioner aperture, tighten the screw and check on the sprocket timing. Plug in the exhaust sprocket the screw-in pins further, replace the secondary timing chain tensioner and fasten the bolts. Last but not least, place back the splined shaft and sleeve to the exhaust camshaft sprocket in proper orientation and apply pressure to push the splined shaft in in a way such that the threaded holes are aligned with the oval apertures in the tooth sleeve in reference to accomplishing the secondary timing chain installation.