Buick 12552128 Sprocket, Camshaft

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To verify camshaft lobe lift, and check for wear, begin by removing the rocker arm cover. Place the number one piston at the top dead center on the compression stroke. Screw a dial indicator on the engine so that the plunger of the indicator rests on the top surface of the first rocker directly below the push rod. Rotate the crankshaft in protractor clockwise so that you can bring dials indicator to zero and then continue until it reads in the opposite direction the maximum cam lobe lift. Measure this and then put the piston back to TDC and do the check on the next valve, taking a piston to TDC in the firing order, rotating the crank 180 for the next cylinder. carrying out the checks, it is possible to compare it with the specified norms; if lobe lift is lower than the established number, then, it is required to install a new camshaft. For removal preheat and remove the alt/front/brake spark plugs, intake manifold, carb, air cleaner, water pump, freon, heater valves, trans cooler bracket, throttle lever linkage, alt & generator front plate & brackets, lower valve cover, engine fan, alternator & brackets, dipstick tube, exhaust manifold, power steering pump & hoses, radiator, plumbing & all brackets, Intake manifold heater crossover, and drivebelts Disconnect the push rods and lifters, and take off the timing gear cover, distributor, and oil pump drive shaft, and the head light bezels, grille, and bumper filler panel. Remove the access panel and unbolt the air conditioning condenser baffles without having to disconnect the refrigerant lines. Place the camshaft so that the holes in the camshaft gear correspond to the drilled holes in the thrust plate, unscrew the bolts and slowly pull out the camshaft and gear out of the block supporting it not to damage the bearings. The crankshaft gear should come off with ease on the crankshaft. After camshaft cleaning, it is required to check the bearing journals to see if they have worn out; if they are worn out, both the camshaft and bearings will require replacement. Check the dimension and roundness of the bearing journals using micro meters and compare the clearance with required specifications. Check the camshaft lobes; if these have changed color or are worn then new lobes may be installed; otherwise the camshaft may be reused. Inspect the camshaft drive and the driven gears and if the camshaft is worn replace both the camshaft drive is well as the driven gears. It is possible to measure gear end clearance and estimate the need in the spacer ring or thrust plate replacement. Camshaft bearing replacement also needs professional tools and therefore transport the block to a machine shop. For installation, lubricate the camshaft journals and the tops of the camshaft lobs, next slide the camshaft into the engine and then install the gear onto the crankshaft sprocket, care must be taken to align the timing marks. Realignment of access holes and usage of Locktite on the threads before the application of thrust plate bolts to the require torque channel in the reverse sequence of the removal process.

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.

To remove and install the timing chain and sprockets, begin by disconnecting the negative battery cable and removing the front cover. Take off the oil slinger from the crankshaft and rotate the engine to align the cam gear timing marks, ensuring the No. 1 cylinder is on the TDC of its compression stroke. From the camshaft, remove the camshaft thrust button and screw, and discard the thrust button. Slide out the cam gear, crankshaft sprocket, and timing chain as an assembly. To install, clean the gasket mounting surfaces and inspect all parts for wear or damage, replacing as necessary. Assemble the timing chain on the cam gear and crankshaft sprockets, align the timing marks on the sprockets to face each other, and align the dowel pin in the cam gear with the index hole in the sprocket; then slide the assembly onto the cam gear and install the sprocket-to-cam gear bolts, tightening it to 37 ft. lbs. Install the new thrust button and the oil slinger, followed by the front cover. Finally, connect the negative battery cable, refill the cooling system, start the engine, allow it to reach normal operating temperatures, and check for leaks.

A few 1996 and all 1997 and later 4.3L V6 and 5.0L, 5.7L V8 engines have a non-reusable plastic front cover that has to be replaced because it is part of the oil pan gasket set and its re-use will lead to oil leaks while 1998 and later 7.4L V8 engines have a front cover and gasket which should Letting start by removing the negative battery terminal and then draining out the cooling system. Take off the upper and lower fan shrouds, drive belt, cooling fan and water pump or coolant manifold. Slightly turn crankshaft 360 degrees more so that No.1 piston is positioned at TDC of the compression stroke though do not turn the crankshaft until the timing chain and sprockets are replaced. The crankshaft pulley, the vibration damper, the crankshaft position sensor and the nut of the wiring harness fastened to the front cover must be disconnected. Take out the oil pan and cover bolts to unbolt the timing chain cover from the block, thus, maybe breaking the gasket seal. For 4.3L V6 and 5.0L, 5.7L V8 engines, the timing chain cover is of composite type and is non-reusable, it is suggested to renew the oil seal simultaneously. Take off the crankshaft position sensor reluctor ring and measure how much timing chain is loose like freeplay, If it reaches or goes past five and eight of an inch, then replace the chain and both sprockets. Remove the camshaft sprocket and chain assembly with the aerospace balance shaft drive gear still fitted to the camshaft. Scrub the contact and mating surfaces of the engine block and if the vehicle is being fitted with a new timing chain, align the key way of the crankshaft sprocket to the Woodruff keyway. N.B. Ensure that the sprocket is fitted to the crank and bolted firmly, do not hammer the sprocket since it may distort. For 4.3L V6 engines, set the balance shaft gears before the timing chain and the camshaft sprocket, that the timing indicators are correctly oriented. Put a non hardening thread locking compound on the sprocket bolt thread and the chain should be lubricated with some fresh engine oil. Crankshaft position sensor reluctor ring, with its dished side outwards, return the crankshaft and apply some RTV sealant on the sealing surface of the engine block and fit new front cover and oil seal assembly. Tighten to 20 Yamaki lb/ft the cover retaining bolts then bolt on the oil pan, vibration damper for crank shaft position sensor with new O-ring. For 2018 and later models, the items are vibration damper, vacuum pump, air conditioning compressor, oil pan, and oil pump. Turn the number one piston into Top Dead Center, pull out the electrical connectors connected to the Camshaft Position Sensor and the Actuator Magnet, and unscrew the cover bolts so as to detach the Timing Chain Cover from the Block. Check the position of the timing marks before unbolting the solenoid valve and the actuator. Check the timing chain tensioner and sprockets for any sign of wear and if the sprocket is worn or has to be replaced, the sprocket must be taken of the crankshaft discreetly. At installation, always purchase the timing chains with the sprockets and clean all of the sealing surfaces; then apply RTV sealant to the timing cover. The timing chain cover is then to be fitted loosely, the bolts are to be tightly fixed in a sequence and a new crankshaft oil seal is to be fitted. But to complete the installation the cooling system should be refilled and the engine oil topped up, the engine oil filter replaced and when the engine is running, check for signs of leakage.

On certain V6 and small block V8 engines, removing the timing cover may require loosening and lowering the oil pan, potentially necessitating a new gasket if it breaks during the process. Accessories obstructing access to the timing chain cover should be detached and moved aside, and big block engines may involve cutting the oil pan gasket and removing the cover.

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.

Begin by removing the torsional damper and crankcase cover.

With the timing marks aligned, slip the chain over the crankshaft sprocket and draw the camshaft sprocket into place with the three retaining bolts, avoiding any hammering or driving that could dislodge the welsh plug at the rear of the engine.

Remove the harmonic bolt and washer without changing the position of the sprockets, using a sharp tap on the wrench handle if necessary.

On certain V6 and small block V8 engines, removing the timing cover may require loosening and lowering the oil pan, potentially necessitating a new gasket if it breaks during the process. Accessories obstructing access to the timing chain cover should be detached and moved aside, and big block engines may involve cutting the oil pan gasket and removing the cover.

Attach the crankshaft sprocket to the crankshaft using a bolt and washer from the puller set.

Use a special puller to remove the crankshaft sprocket.