GMC 12458911 Chain Kit,Timing (W/Sprockets)

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To take out the water pump first disconnect, then unbolt and then disconnect the crankshaft drivebelt pulley from the vibration damper, using a six-point socket and breaker bar for the tight vibration damper bolt. Place the number four piston at TDC on the compression stroke, do not rotate the crankshaft until the timing chain and its sprockets are replaced. Finally, unscrew the bolt on the crankshaft front and unbolt the vibration damper employing a puller that places as force on the damper hub in order to prevent damage. For the 1995 and models remove the crankshaft position sensor located on the timing chain cover and pull the harness off. Move on to take off the oil pan further to take off the timing chain cover from the engine block using a putty knife or a flat head screwdriver if rust have bonded it. 1995 and later models only, check the timing chain cover if removed, clean the detent confronting face of the camshaft sprocket and measure the timing chain free play, if more than 5/8 inch replace the chain and sprockets. For 1995 and later models, also take the Crankshaft Position Sensor reluctor ring and, for 2004 and later models, the timing chain tensioner. Untighten and eliminate the bolts fastening the timing chain sprocket to the camshaft, then, take off the camshaft sprocket and timing chain as a single unit while paying attention to the relative positions of the timing marks. When withdrawing the crankshaft sprocket you should use a two or three jaw type gear puller; be careful not to scratch the crankshaft threads. For installation, the housing as well as metal cover should be clean and free from any dist or deformation and gasket surface of the cover should be restored as required. Just ensure that the balancer shaft gears are adjusted before fitting the camshaft sprocket and tighten the crankshaft timing chain sprocket making sure that the key is in the right position. If it is, turn crankshafts so that its timing mark is on the first horizontal position, feed the timing chain over the camshaft sprocket and then install the camshaft sprocket such that its timing mark comes into contact with that of the crankshaft one. For 1995 and later models, install the Crankshaft Position Sensor reluctor with the dished side facing out, use thread locking compound on the camshaft sprocket fasteners and use poly-graphite withe timing chain. For metal timing chain covers, you should smear RTV sealant on both faces of the gasket and for composites apply new cover and crankshaft front oil seal and smear RTV sealant on the mating surface. Put on the timing chain cover and fasten the bolts, then, engage the oil pan and Crankshaft Position Sensor using a new gasket. Clean and apply oil to the crankshaft front oil seal and the sealing surfaces of the vibration damper; fit the damper and replace the bolt with the right one and tighten to the recommended torque. Last but not the least, perform the rest of the steps of installation in the order of the steps of removal at the reverse sequence.

Begin by removing the cover, then isolate it from the negative battery cable. After that, remove fan shroud upper part, drive belt, fan/clutch assembly, water pump pulley, crankshaft pulley and hub. Remove the drive belt tensioner bracket and Timing Cover-to-engine block bolts next. Utilize a gasket scraper to erase any old gasket material and clean any of the sealing surfaces. To remove the timing chain; temporarily install crankshaft pulley hub and bolt; rotate crankshaft to align timing marks on crankshaft and camshaft sprockets; push back timing chain tensioner plunger and insert pin to retain plunger; using prybar holding engine while removing camshaft bolt; carefully prying camshaft sprocket off. Check for damage or wearout on timing chain and sprockets before replacing if necessary. Mesh new timing chains with camshafts; put them into engagement with crankshafts at their sprocket's teeth; aligning timing marks; installing tightening camshaft sprocket bolt; releasing tensioner; lubricating chain/sprocket; rotating engine to check alignment of timing marks; applying RTV sealant to oil pan sealing surface; finally securing front cover using new rubber seal.

Disconnecting the negative battery cable is the first step in removal and installation of the Timing Cover. To remove, you will have to remove upper and lower fan shrouds, drive belt, cooling fan and water pump. The number four piston must be positioned at TDC on the compression stroke, then remove the drive belt pulley and crankshaft damper. If applicable, don't forget to take out the crankshaft position sensor and wiring harness nut. Loosen front oil pan nuts before removing cover bolts when separating Timing Cover from block and breaking gasket seal if necessary. Note that for some engines, the front cover may be made of composite material and should be replaced rather than resealed. Just inside the front cover, pull off crankshaft position sensor reluctor ring which is attached to a camshaft sprocket and chain assembly. For an old gasket material use a gasket scraper to scrape it off; cleaning lacquer thinner or acetone should be wiped over sealing surfaces of engine cover and block; inspecting flange condition of a cover is recommended. Make sure that when installing a Woodruff key line up coincides with both crankshaft sprocket's as well as balance shaft gears'. Use clean engine oil to lubricate the chain; put Loctite on camshaft sprocket bolt threads before installing them tightly or tighten them after installing using Loctite. Apply RTV sealant in U-shaped channel on bottom side of the cover check oil pan-to-block joints; also check whether there are any leaks between housing halves in place where they meet with each other in front of timing chain area that is why you need to apply RTV sealant between them too. Thin layer of RTV sealant should be spread over both sides of new gasket so that it can be positioned on engine block by dowel pins thus holding it firmly in place. Finally install Timing Cover and tighten bolts taking into account whether it is necessary to remove or pry down oil pan for access. Lastly, apply moly-base grease or clean engine oil onto the vibration damper hub's oil seal contact surface, put the damper on the crankshaft, and proceed with other remaining installation steps including using new O-ring for crankshaft position sensor.

Begin by removing the cover, then isolate it from the negative battery cable. After that, remove fan shroud upper part, drive belt, fan/clutch assembly, water pump pulley, crankshaft pulley and hub. Remove the drive belt tensioner bracket and Timing Cover-to-engine block bolts next. Utilize a gasket scraper to erase any old gasket material and clean any of the sealing surfaces. To remove the timing chain; temporarily install crankshaft pulley hub and bolt; rotate crankshaft to align timing marks on crankshaft and camshaft sprockets; push back timing chain tensioner plunger and insert pin to retain plunger; using prybar holding engine while removing camshaft bolt; carefully prying camshaft sprocket off. Check for damage or wearout on timing chain and sprockets before replacing if necessary. Mesh new timing chains with camshafts; put them into engagement with crankshafts at their sprocket's teeth; aligning timing marks; installing tightening camshaft sprocket bolt; releasing tensioner; lubricating chain/sprocket; rotating engine to check alignment of timing marks; applying RTV sealant to oil pan sealing surface; finally securing front cover using new rubber seal.

Begin by removing the cover, then isolate it from the negative battery cable. After that, remove fan shroud upper part, drive belt, fan/clutch assembly, water pump pulley, crankshaft pulley and hub. Remove the drive belt tensioner bracket and Timing Cover-to-engine block bolts next. Utilize a gasket scraper to erase any old gasket material and clean any of the sealing surfaces. To remove the timing chain; temporarily install crankshaft pulley hub and bolt; rotate crankshaft to align timing marks on crankshaft and camshaft sprockets; push back timing chain tensioner plunger and insert pin to retain plunger; using prybar holding engine while removing camshaft bolt; carefully prying camshaft sprocket off. Check for damage or wearout on timing chain and sprockets before replacing if necessary. Mesh new timing chains with camshafts; put them into engagement with crankshafts at their sprocket's teeth; aligning timing marks; installing tightening camshaft sprocket bolt; releasing tensioner; lubricating chain/sprocket; rotating engine to check alignment of timing marks; applying RTV sealant to oil pan sealing surface; finally securing front cover using new rubber seal.

Disconnecting the negative battery cable is the first step in removal and installation of the Timing Cover. To remove, you will have to remove upper and lower fan shrouds, drive belt, cooling fan and water pump. The number four piston must be positioned at TDC on the compression stroke, then remove the drive belt pulley and crankshaft damper. If applicable, don't forget to take out the crankshaft position sensor and wiring harness nut. Loosen front oil pan nuts before removing cover bolts when separating Timing Cover from block and breaking gasket seal if necessary. Note that for some engines, the front cover may be made of composite material and should be replaced rather than resealed. Just inside the front cover, pull off crankshaft position sensor reluctor ring which is attached to a camshaft sprocket and chain assembly. For an old gasket material use a gasket scraper to scrape it off; cleaning lacquer thinner or acetone should be wiped over sealing surfaces of engine cover and block; inspecting flange condition of a cover is recommended. Make sure that when installing a Woodruff key line up coincides with both crankshaft sprocket's as well as balance shaft gears'. Use clean engine oil to lubricate the chain; put Loctite on camshaft sprocket bolt threads before installing them tightly or tighten them after installing using Loctite. Apply RTV sealant in U-shaped channel on bottom side of the cover check oil pan-to-block joints; also check whether there are any leaks between housing halves in place where they meet with each other in front of timing chain area that is why you need to apply RTV sealant between them too. Thin layer of RTV sealant should be spread over both sides of new gasket so that it can be positioned on engine block by dowel pins thus holding it firmly in place. Finally install Timing Cover and tighten bolts taking into account whether it is necessary to remove or pry down oil pan for access. Lastly, apply moly-base grease or clean engine oil onto the vibration damper hub's oil seal contact surface, put the damper on the crankshaft, and proceed with other remaining installation steps including using new O-ring for crankshaft position sensor.

Replace the timing chain and both sprockets.

Inspect the timing chain tensioner, camshaft, and crankshaft sprockets for wear, and if necessary, remove the crankshaft sprocket with a puller.

Temporarily install the crankshaft pulley hub and bolt, align the timing marks on the crankshaft and camshaft sprockets, push back the timing chain tensioner and insert a pin to retain it, use a prybar to hold the engine while removing the camshaft bolt, and carefully pry off the camshaft sprocket.

Loosening the front oil pan nuts allows for easier removal of the timing chain cover.

Before removing the timing chain cover, the following components should be removed: upper and lower fan shrouds, drive belt, cooling fan, water pump, drive belt pulley, crankshaft damper, crankshaft position sensor, and the wiring harness nut if applicable.