GM 12665857 Actuator Assembly, Camshaft Position

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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.

For mid-2007 and later models, follow a similar process, ensuring the crankshaft is rotated to the correct position and the appropriate locking tools are installed.

Before starting the engine, rotate the crankshaft by hand to check for resistance, which may indicate potential issues.