GMC 10144121 Sprocket,Camshaft

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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.

After removing the front cover, it's recommended to remove the crankshaft position sensor reluctor ring if applicable. Measuring the timing chain's free play is important, and if it exceeds 5/8 inch, replacement is recommended alongside the gears. The camshaft sprocket and chain are removed as a unit, with proper alignment being crucial.

Most engines use a large bolt threaded into the crankshaft's nose to secure the vibration damper. It should be removed with a puller that exerts force solely on the damper hub to avoid damage.

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.

During installation, lubricate the chain with clean engine oil and apply Loctite to the camshaft sprocket bolt threads. Apply RTV sealant to the U-shaped channel on the bottom of the cover and a thin layer of RTV sealant to both sides of the new gasket.

After installing the timing chain cover, lubricate the oil seal contact surface of the vibration damper hub with moly-base grease or clean engine oil. Install the damper on the crankshaft and follow the remaining installation steps, including using a new O-ring for the crankshaft position sensor.

Mesh it with the camshaft sprocket and engage it with the crankshaft sprocket, align the timing marks, install and tighten the camshaft sprocket bolt, release the tensioner, lubricate the chain and sprocket, rotate the engine to check the alignment of the timing marks.