GM 91177257 Belt,Timing (On Esn)

To remove the components, unbolt the negative terminal of the battery and align the number one piston to top dead centre. Take off the valve cover, in the case with the Sprint models unlock the nuts and turn the adjustment screws backward. Apply the parking brake and turn the rear wheels so that they are blocked, then place wedges under the front of the vehicle and it up on jackstands. Remove the four bolts which hold in place the water pump pulley and take off the drivebelts. Take out the right inner fender rubber plug, and also the crankshaft and water pump drivebelt pulleys. In as much as the crankshaft center bolt will not be necessary if the timing belt is being replaced, this bolt will be necessary if the crankshaft sprocket will be replaced. To withdraw it, first, lock the pulley with a rag or duct tape and chain wrench, then, with the help of a breaker bar. Unfasten all the bolts that hold down the timing belt cover, then take it out. Look also at #5 in figure above, in case the timing belt is to be reused, paint an arrow at the belt to show the rotation direction. Relax the adjusting nut and pulley bolt then using your hand turn the tensioner pulley in the direction of the water pump and lock it for some time. Remove the timing belt over the sprockets and temporarily put it aside. In case of replacing the oil pump or the crankshaft front oil seal, remove the crankshaft sprocket and the belt guide with attention made to the position. To remove the camshaft sprocket to replace it unscrew the camshaft sprocket bolt holding a large screwdriver in your hand to stop it turning while doing so and remove the cover to get to the seal. Look at the face of the tensioner pulley for roughness and movement and look at the sprockets for signs of wear and tear. Check the belt for any signs of cracks, wear or oil residues and replace the belt if you have to. On reassembly, refit the camshaft seal cover and the timing belt sprockets with the camshaft sprocket aligned by a dowel. Insert the belt guide over the crankshaft prior the fitting of the crankshaft sprocket but ensure that the key way is in line with the crankshaft key. Ensure the letters on the crankshaft and camshaft sprockets are facing upwards, slide the timing belt between the crankshaft and camshaft sprockets ensuring that there is tension. Loosen the tensioner adjusting nut, turn the crankshaft in anticlockwise direction for two full turns and then tighten the nut again. By positioning the notch of the crankshaft pulley against the raised area of the sprocket and holding the crankshaft still apply the bolts and nuts adequately. Rotate the crankshaft two times in the clockwise direction and align the timing marks for the valves again and if they do not match then again adjust the valve. Finally, again looseskin the nut around the tensioner bolt, then replace rest of the assemblies in reverse manner. Last but not the least, again start the engine, adjust the ignition time, and conduct road test of the vehicle.