GM 340235 Sprocket, Camshaft

If you are dealing with a vehicle manufactured from 1995 onwards, then the V6 and small block V8 models will have non-reusable plastic front cover, which must be discarded as it cannot be reused after being removed to prevent any oil leaks. In contrast, for 7.4L V8 engines produced after 1996, there is a reusable front cover gasket and front cover that might only require a gasket replacement if the original one becomes damaged. The first step in removing the timing belt is removing the water pump, followed by unbolted crankshaft drivebelt pulley from the vibration damper. Once the number one piston is at TDC on the compression stroke, rotate crankshaft an additional 360 degrees giving caution not to turn it until when installing timing chain and sprockets. On most engines there is usually a large bolt threaded into the nose of the crank shaft used to secure the vibration damper and this necessitates its removal with a puller designed to apply force strictly on the damper hub so as not to damage it. When taking out the timing cover on certain V6s and small block V8s it may become necessary to loosen and drop down oil pan, requiring replacement of its gasket should it crack in this operation. Any accessories that obstruct access to timing chain cover should be removed or pushed away while on big block engines further steps include cutting oil pan gasket and remove cover. For 1995-present models remove crankshaft position sensor reluctor ring and for 7.4L engines there is special tool that's required for this purpose after which it must be replaced. One way of testing for timing chain free play is checking whether such play exceeds or falls below half inch and if so replace gears also. Next comes removing camshaft sprocket with chain assembly as a single unit; ensure proper alignment especially in cases where V6s or small block V8s have oil pan gasket deteriorated and so replace it. When it comes to gasket removal and surface cleaning, see if the cover flange needs any correction. Followed by, installing new parts like crankshaft sprocket, camshaft sprocket and vibration damper should be carried out with emphasis on correct alignment of keyways. For some engine types an application of lube oil is required while others must have sealant applied. Finally, the rest of the process is reversing the order in which these steps were taken.

Remove the timing chain cover and temporarily install the harmonic balancer bolt and washer in the end of the crankshaft. Turn the crankshaft so that the sprocket timing marks are positioned toward each other, then remove the harmonic bolt and washer without changing the position of the sprockets, using a sharp tap on the wrench handle if necessary. Next, remove the front crankshaft oil slinger and the camshaft sprocket bolts, followed by the oil pan. Use two large screwdrivers to carefully pry the camshaft sprocket and then the crankshaft sprocket forward alternately until the camshaft sprocket is free, then remove both the camshaft sprocket and chain, and work the crankshaft sprocket off the crankshaft. If the chain is not stretched and parts are to be re-used, clean the timing chain, sprockets, and crankshaft oil slinger thoroughly in the proper solvent. If the engine was not rotated while the chain and sprockets were off, install the sprockets and chain with the timing marks perfectly in line, exactly as they were on removal. If the engine was rotated, temporarily install the sprockets and turn the crankshaft until the number one piston is at Top Dead Center and the camshaft O mark is straight down and on the centerline of both shafts. Remove the sprockets and assemble the timing chain on both sprockets, sliding the chain assembly onto the shafts with the O marks in their closest together positions and in line with the sprocket hubs. Assemble the oil slinger on the crankshaft with the inside diameter against the sprocket, then install the camshaft sprocket bolts and torque-tighten to specifications. Finally, install the oil pan using a new gasket and the timing chain cover.

In case the engine has been removed from the vehicle, then some of the steps, which follow may not be applicable. Among other works, there is a necessity of crankcase cover and torsional damper's removal in order to continue with the following works. Hold the engine until the markings made on the camshaft as well as the crankshaft sprockets align with each other; it is advisable not to take off either the sprocket or the chain before this is achieved. Third, turn the front crankshaft sprocket and remove the three 12mm camshaft sprocket retaining bolts that are connected to the camshaft sprocket and timing chain assembly. If the assembly does not lift off the front of the engine easily then use a soft-faced mallet to tap the camshaft sprocket. If it is necessary to remove the crankcase sprocket, apply a special puller for this goal. Centre the crankshaft sprocket on the crankshaft by engaging the key way in the sprocket to the key in the crank before securing with a bolt and washer from the puller set. Align the timing chain with the camshaft sprocket so that there is only tension connecting the crankshaft sprocket. With the timing marks aligned, get the chain over the crankshaft sprocket, and bring the camshaft sprocket in with three bolts, and make sure that a small hole in the sprocket hub aligns with the dowel pin on the end of the camshaft before tightening the bolts. Do not hit or pound the camshaft sprocket on to place as this may injure or displace the welch plug at the rear side of the engine. Then verify if the chain and both sprockets are there.Intention is to align the timing marks of both these sprockets, if not adjust in a manner that the same are aligned.Above step may also involve detaching the camshaft sprocket. Last but not least, give it a spray of the engine oil then begin to reinstall the components in the manner in which they were removed.

If you are dealing with a vehicle manufactured from 1995 onwards, then the V6 and small block V8 models will have non-reusable plastic front cover, which must be discarded as it cannot be reused after being removed to prevent any oil leaks. In contrast, for 7.4L V8 engines produced after 1996, there is a reusable front cover gasket and front cover that might only require a gasket replacement if the original one becomes damaged. The first step in removing the timing belt is removing the water pump, followed by unbolted crankshaft drivebelt pulley from the vibration damper. Once the number one piston is at TDC on the compression stroke, rotate crankshaft an additional 360 degrees giving caution not to turn it until when installing timing chain and sprockets. On most engines there is usually a large bolt threaded into the nose of the crank shaft used to secure the vibration damper and this necessitates its removal with a puller designed to apply force strictly on the damper hub so as not to damage it. When taking out the timing cover on certain V6s and small block V8s it may become necessary to loosen and drop down oil pan, requiring replacement of its gasket should it crack in this operation. Any accessories that obstruct access to timing chain cover should be removed or pushed away while on big block engines further steps include cutting oil pan gasket and remove cover. For 1995-present models remove crankshaft position sensor reluctor ring and for 7.4L engines there is special tool that's required for this purpose after which it must be replaced. One way of testing for timing chain free play is checking whether such play exceeds or falls below half inch and if so replace gears also. Next comes removing camshaft sprocket with chain assembly as a single unit; ensure proper alignment especially in cases where V6s or small block V8s have oil pan gasket deteriorated and so replace it. When it comes to gasket removal and surface cleaning, see if the cover flange needs any correction. Followed by, installing new parts like crankshaft sprocket, camshaft sprocket and vibration damper should be carried out with emphasis on correct alignment of keyways. For some engine types an application of lube oil is required while others must have sealant applied. Finally, the rest of the process is reversing the order in which these steps were taken.

Loosen the cable on the negative terminal of the battery, right, then remove the vibration damper and crankcase cover. Remove all of the spark plugs from the engine. Loosely replace the crankshaft pulley bolt with several thickness of washer or spacer and rotate the crankshaft in anticlockwise direction to align the timing mark on crank shaft and cam shaft so that the camshaft sprocket and chain will also be properly aligned. Head the camshaft sprocket mounting bolts, held the camshaft sprocket from the camshaft and get rid of the sprocket and chain. If required, employ the special tool of puller to remove the crankshaft sprocket. Fits the crankshaft sprocket on the crankshaft in the same way in which it was removed by using one of the bolts and washers from the puller. Place the timing chain above the camshaft sprocket and provide some tension by having some part of the chain hang over the crankshaft sprocket. When the timing marks perfectly align, then place the chain over the crankshaft sprocket and then slide the camshaft sprocket over and tighten the bolts. After that check the alignment of the timing marks both on camshaft and crank shaft sprockets where camshaft sprocket mark should be made at 6 'o' clock and crank sprocket mark should be made at 12 'o' clock and a line passing through the center of both sprockets must pass through both timing marks. If misaligned, position the camshaft sprocket as it is indicated that upon proper alignment, the engine is set in a manner whereby the number six piston is at TDC on the compression stroke. Last but not the least, pour some drops of engine oil on the chain and fit all the other parts starting from the one, which was removed last.

Unbolt the air conditioning condenser baffles without disconnecting the refrigerant lines. Align the holes in the camshaft gear with the thrust plate bolts, remove the bolts, and carefully pull the camshaft and gear assembly out of the block, supporting it to avoid bearing damage. The crankshaft gear should slide off easily.

Remove the bolts securing the timing chain sprocket to the camshaft, then detach the camshaft sprocket and chain as an assembly, noting the positions of the timing marks.

Use two large screwdrivers to carefully pry the camshaft sprocket and then the crankshaft sprocket forward alternately until the camshaft sprocket is free.

Turn the engine until the marks on the camshaft and crankshaft sprockets are in alignment, ensuring not to remove either sprocket or the chain until this is completed.

Disconnect the cable from the negative battery terminal and remove the vibration damper.