GM 12684830 Actuator Assembly, Camshaft Position

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The timing system is sophisticated, and one is in big trouble if they get it wrong; as such, only professionals should attempt this process and one should seek professional advice if in doubt. Before detaching the timing chain(s) from its/their sprockets, make sure that all sprockets possess timing marks; in the absence of a mark on the crankshaft sprocket, a particular tool (EN 46111) must be used. This procedure requires two special tools to lock the camshafts, namely the part numbers for these tools are; part no 46105-1 and part no 46105-2. This can be done by first disconnecting the negative terminal of the battery, then, relieve the fuel system pressure, drain the engine coolant, then remove the drive belt with the tensioner . Go ahead and pull the lower intake manifold, valve covers, water pump, power steering pump, crank shaft pulley then the crank and camshaft position sensors. Pull M15 connectors off the camshaft position actuator valves, delete the thermostat housing and unscrew the timing chain cover. Run the 10 mm x 1.5 mm bolt in the cover to loosen it lightly from the block and adjust the crankshaft sprocket with the timing mark on/with the oil pump housing. Check the camshaft timings before releasing the bolts of the timing chain tensioner and the guides of the timing chain. Do the same for the lower timing chain and the timing chain for the other cylinder head, the tensioners very sensitive. Check the timing chain cover for any signs of rust and clean all of the parts also check the guides and sprockets for wear or damage. Release the tension of the straps and make sure that the tensioners remain in their respective status, which is the retracted one. Before starting the engine the crankshaft should be rotated by hand with slight resistance to determine some problems. Position the crankshaft sprocket in such a manner that the Woodruff key is showing, and its timing marks are also properly visible; position the timing chains and guides and tensioners in their proper positions and align properly. Remove the old sealant form the block and cover, place a new seal down then apply RTV sealant before placing the timing chain cover, then fasten the bolts in the proper sequence. Last but not the least, the rest of the installation is in the exact opposite of the removal process.

While performing the timing system, care should be taken since an error can result to the severe damage of the engines; this procedure should be performed by an expert, and if a question arise, one should seek advice. Ensure that all the sprockets contain the timing marks and in that case ensure that the engine is turned to the correct positions for the removal of the timing chain(s). This operation needs three special tools to immobilise the camshafts and these tools should be procured in advance. Start with removing the negative terminal of the battery, draining the oil, and the oil filter and spark plugs to help with turning of the engine. Move on to the Discover more removal of drive belt, intake manifold, valve covers, water pump, power steering reservoir bracket, alternator, crankshaft pulley, CMP sensor bolts, electrical connectors for the camshaft position actuator valves, engine mount bracket, drive belt idler pulley, and thermostat housing. All the bolts to be pulled out of the timing chain cover; a bolt should be employed to lever on so as to remove the bolt holding the cover. Adjust the crankshaft to set the primary timing chain sprocket with the mark on the oil pump housing also make sure that flat segments on camshaft are set. That means the timing chain tensioner bolts and guides must be removed and once again you need to be careful because the tensioner is under spring tension. Do the same for the lower timing chain; check the conditions of each component for wear or damages, and then wash them. During installation stage make sure that on the crankshaft sprocket, the special retaining tool is fitted on the camshaft and that all the timing chains, guides and tensioners are well fitted with correct alignment marks. Once all these are lined and aligned well, the sealing surfaces should then be cleaned, a new seal fitted on the timing cover, some RTV sealant applied and then placing the cover well before tightening the bolts properly and in the sequence that is equally recommended. The rest of the installation is done in the reverse order that is used in the removal process.

If necessary, remove the idler sprockets and mark the relationship between the camshaft sprockets and their respective camshaft before removing the sprocket bolt.

Align the timing mark with the 9 o'clock position.

Clean the sealing surfaces, install a new seal in the timing cover, apply RTV sealant, and carefully position the cover before tightening the bolts in the correct sequence. The remainder of the installation follows the reverse order of removal.