Chevrolet 12507945 Bearing, Camshaft #1

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The procedure applies to 2.0/2.2 liter four-cylinder overhead valve engines and all V6 engines, but removing the engine from the vehicle and mounting it on a stand will be necessary because the space is not enough for removing the camshaft. To check camshaft lobe lift with the cylinder head installed, first remove the rocker arm cover(s) and rotate number one piston to TDC on compression stroke. Loosen rocker arm nuts, swing aside rocker arms, and then attach a dial indicator to engine with its plunger positioned on top of the first rocker arm just over the pushrod. Zero out the dial indicator before gently rotating crankshaft clockwise until needle stops and reverses indicating maximum cam lobe lift. Write down this value and do the same for all other valves while making sure that each piston is at TDC when on compression stroke.If camshaft lobe lift is less than specified, it shows that they are worn out so they need to be replaced with new ones. An alternative method when cylinder head(s) have been removed involves measuring at its highest point while taking a reference point through its base circle that should be perpendicular to the lobe using micrometer.Camshaft removal requires among other things removal of timing chain and sprockets, lifters, pushrods as well as oil pump drive stick.Follow these steps to remove your camshafts: Remove timing chain as well as sprockets; remove lifters ,pushrods and oil pump drive; use long bolts for supporting cams during removal ensuring that you take care of damaging bearings near block.Inspect camshaft surface against wear condition of bearing journals or lobes how about oil pump drive and gears, Provided components are in good shape and specifications have measured up, reuse is possible.Nevertheless, inspect inside diameter of bearing journals of block's bearings for wear or damage or determine bearing oil clearance which is an essential criterion for estimating excessive clearance that requires new bearings.Bearing tools for camshaft bearing replace or automotive machine shop is needed.

Utilize a specific set of tools for bearing removal and installation, ensuring the correct order of removal and installation for each bearing.

Install new bearings by reversing the removal procedure, ensuring all oil holes are aligned, and drive the front bearing approximately 1/8 inch from the front of the cylinder block to uncover the oil hole for the timing gear oil nozzle.

Reject any camshaft that does not meet specified limits.

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

Camshaft bearing replacement requires special tools and expertise.

Repeat the measurement for each remaining valve, keeping in mind that intake and exhaust valves may have different specifications.

Before installing the camshaft, ensure that number 1 cylinder is at TDC and coat each of the lobes and journals with lithium-based grease.

Check the end clearance of the thrust plate with a feeler gauge, replacing the spacer ring if clearance is less than .0015 inches or the thrust plate if more than .0050 inches.

Start with the front and rear bearings to guide the centering of the remaining bearings, ensuring that the oil holes in the bearings align with the oil holes in the block.

Deep scoring requires a new camshaft.