Chevrolet 14002525 Bearing, Camshaft

After removing the camshaft from the engine, clean it with solvent and dry it, then inspect the bearing journals for uneven wear, pitting, and signs of seizure; if damaged, both the camshaft and bearings need replacement. Measure the bearing journals with a micrometer to check for excessive wear or out-of-round conditions, replacing the camshaft if it exceeds 0.001-inch out-of-round. Examine the camshaft lobes for heat discoloration, score marks, chipped areas, pitting, and uneven wear; if the lobes are in good condition and the lobe lift measurements are within specified limits, the camshaft may still be usable. For Lash Adjusters that have been sticking due to sludge and varnish buildup, clean them thoroughly without mixing them up, ensuring they are reinstalled in their original locations. Inspect each Lash Adjuster for scoring and galling, checking the pushrod seat and heel for wear; if any Lash Adjuster heel is concave or if the bottom of any Lash Adjuster shows excessive wear, replace the entire set. If conventional valve Lash Adjusters require replacement, install a new camshaft as well; roller type Lash Adjusters can be reused with a new camshaft. Worn Lash Adjusters should be replaced as internal components are not sold separately, although cleaning may restore functionality. To dismantle a valve Lash Adjuster, hold the plunger down and extract the retainer ring, then remove the pushrod seat and oil metering valve, followed by the plunger, check ball, and spring. Clean all components with solvent and inspect for wear, ensuring that a contaminated Lash Adjuster can operate properly after reassembly. If a Lash Adjuster is worn out, replace it and clean any sealer coating from new Lash Adjusters before reassembly, which involves placing the check ball, inserting the spring and retainer, and filling the assembly with oil before installing the metering valve and pushrod seat. When reinstalling Lash Adjusters, ensure they are placed in their original bores with oiling orifices facing the front of the engine, and coat each Lash Adjuster with moly-base grease or engine assembly lube. Camshaft bearing replacement requires special tools and expertise, so it is advisable to take the block to an automotive machine shop for proper handling.

Check the bearing surfaces and the surface of the cam lobes; light pitting or scratching may be smoothed with fine emery cloth or an oil stone, but if the camshaft is deeply scored a new one will be necessary. Camshafts should be mounted on V-blocks and employed with a dial gauge to measure camshaft lobes lift and run-out and exclude camshafts that do not meet the stipulated camshaft lobe lift and run-out. Use a micrometer to measure the journal diameters; it is mandatory to scrap any camshaft which does not conform to the above limits. In the case where either camshaft bearings are worn out or in some conditions damaged, then they have to be replaced; it can be done by having to detach the crankshaft but maintaining cylinder heads and pistons. To avoid getting damaged, the connecting rod bolts should be taped before the removal of the crankshaft and the connecting rods should also be taped to the side of the engine to minimize on interference when removing the bearings. Take out the camshaft rear cover from the top of the cylinder block. Bearing can be removed using GM tool part number J-6098 or a like bearing remover / installer tool according to the instructions. The same set of tools is used to set the camshaft bearings where, for instance, the front and the rear bearings help in centering the remainder of the bearings so that the oil hole in the bearings will match the oil hole in the block. Remove any debris, oil or old gasket material from the camshaft rear cover, then give the cover a layer of RTV or any other equivalent sealant with 1/8 in x 3mm diameter around the sealing surface before fixing the cover on the engine block. Finally, reinstall the crankshaft.

Clean any dirt, oil, or old gasket material from the camshaft rear cover, then apply a 1/8-in (3 mm) diameter bead of RTV or equivalent sealant around the sealing surface before bolting the cover to the engine block.

To extract the camshaft, assemble a puller with the appropriate components, such as the puller screw, expanding collet, and back-up nut. Insert this assembly into the camshaft bearing for removal. Repeat this process for each bearing, except the front one, which can be extracted using a spacer.

After completing the checks, compare the results to the specifications; if the lobe lift is below the specified value, it indicates wear and necessitates a new camshaft.

The bearing surfaces and the surfaces of the cam lobes should be examined.

Remove the two camshaft thrust plate screws by working through the holes in the camshaft gear.

Clean the camshaft with solvent and inspect the bearing journals for wear, pitting, or seizure; if damaged, both the camshaft and bearings will need replacement.