GM 12627107 Chain Assembly, Timing

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The time-keeping system is very much intricate and any wrong doing to the system is very likely to cause a very severe harm to the engine. People who have little experience in the matter certainly should not attempt this procedure; if there is any doubt about one's ability, one should seek the advice of a specialist. Recheck all work to be carried out before starting the engine. This is quite a complicated process and for that, should read through all the instructions and gather all the requisite tools and components for the process such as new camshaft sprocket bolts. Starting with decreasing the fuel pressure, the removal of spark plugs, setting the engine to a TDC, the removal of the negative cable to the battery, the removal or the valve cover, the draining of the engine oil, and the final removal of the drive belt together with the timing chain cover. Subsequently, take out the upper timing chain guide bolts and guide and then compress the tensioner, finally, take out the tensioner and gasket. Further, the rear and front timing chain guides, the timing chain fixed on crankshaft and camshaft sprockets, and timing chain tensioner are to be eradicated. Disconnect the timing chain oil nozzle by unscrewing it with an Allen wrench; slide off the camshaft sprocket(s) also and dispose the old bolt. For 1.5L engines, it is necessary to remove the upper oil pan and oil pump, turn the oil pump drive chain tensioner away from the chain and lock it in the retracted position and then, remove the tensioner. Relieve the oil pump chain from the sprockets and wash all the parts with solvent which should then be checked for signs of wear or damage, should there be any replace them. Prior to engaging the engine crank the crankshaft should be manually rotated several times, preferably two at least and it should be felt that there is some load on the shaft. For the 1.5L engines, position the oil pump drive chain over the crankshaft sprocket, then install oil pump along with the tensioner and properly adjust the position of the spring of the tensioner and tightly fix the tensioner bolt. Let go of the retaining tool then fit in the upper oil pan. On the timing chain, fit the oil nozzle as well as the camshaft positions should also be checked before the fitting of the camshaft sprockets and tightening of new bolts. Grasp the camshaft with a wrench and tighten the nut for the actuator sprocket; place the crankshaft sprocket on the crankshaft so that the keyway will fit into place. Position the timing chain of the car over the crankshaft sprocket and over the camshaft sprockets so that the timing marks matched and then add the timing chain guides and the tensioner and fasten all the bolts to the correct measurement of torque. Check that the colored links of the timing chain coincide, install the timing chain cover and the valve cover and complete the assembly the other way round. Last but not the least inspect the exhaust system then replace the oil filter, add oil to the crankcase, connect the battery, add thermostat and coolant to the cooling system then start the engine to check the engine for leaks.

Detach the timing chain cover mounting bolts and separate the timing chain cover from the block, using a putty knife if necessary to break the gasket seal, being cautious not to damage the aluminum cover.

During installation, align the crankshaft sprocket with the woodruff key, ensuring timing marks are visible and aligned. Then install the timing chains and guides, tightening bolts to the specified torque.

Start by disconnecting the negative battery cable, draining the oil, and removing the oil filter.