In order to install and remove the rear wheel drive GLC and 1979-82 626, drain the cooling system, then remove the cooling fan, radiator cowling, drive belts and fan pulley. Then remove the water pump and the blind cover that is above the crankshaft pulley. Insert the slipper head of the push in the chain adjuster and ensure that you fix a chain adjuster guide or another clamping tool in the chain adjuster, thereafter loosen the chain adjuster and unscrew the chain adjuster with the guide installed. To install, hold the clamping tool on and attach the chain adjuster to the cylinder block and then adjust the chain tension by slightly rotating the crankshaft, removing the blind plugs and aluminum washers of the timing chain cover, loosening the guide strips that the screws attaching to and then pushing the top of the chain guide strip through the correct opening. Install the blind cover and gasket, the spring-loaded slipper head with the clamping tool removed, install the blind cover and gasket, the cylinder head cover (where applicable) and the blind plugs with aluminum washers. Last stuff to install includes water pump with new gasket, fan pulley and drive belts with the appropriate tension, cooling fan and radiator cowling, and fill the cooling system to the right level. In the case of the front wheel drive GLC, the chain tensioner is on the left upper side of the timing chain cover, and it works with the spring and hydraulic pressure that has a one way locking system and automatic release mechanism. To take out the tensioner, unscrew the two retaining bolts and examine the amount of teeth on the sleeve; in case, there are thirteen or more notches on it, the timing chain must be replaced. Installation requires pushing the sleeve back into the body then locking it with the swivel catch and then attaching the tensioner to the timing chain cover which will automatically further position once the engine has turned one to two times.