Cadillac 12453172 Bearing, Camshaft

A special tool can be used to remove the lifters.

Camshaft bearing replacement requires special tools and should be done at an automotive machine shop.

Measure the inside diameter of each camshaft bearing, taking two measurements at each bearing, and subtract the bearing journal diameters from the corresponding bearing inside diameter measurement.

To determine cam lobe wear, you should first position the number one piston at TDC on the compression stroke. Then, loosen the rocker arm nuts and pivot the rocker arms sideways. Afterward, mount a dial indicator on the engine and position the plunger against the top of the first pushrod. Zero the dial indicator and slowly turn the crankshaft in the normal direction of rotation until the indicator needle stops and begins to move in the opposite direction. Record this figure and repeat the check for each valve.

The camshaft should always be thoroughly inspected before installation, and endplay must be checked prior to removal.

To determine cam lobe wear, you should first position the number one piston at TDC on the compression stroke. Then, loosen the rocker arm nuts and pivot the rocker arms sideways. Afterward, mount a dial indicator on the engine and position the plunger against the top of the first pushrod. Zero the dial indicator and slowly turn the crankshaft in the normal direction of rotation until the indicator needle stops and begins to move in the opposite direction. Record this figure and repeat the check for each valve.

Use a micrometer to measure the bearing journals, ensuring they are not excessively worn or out-of-round; if they exceed 0.001-inch out-of-round, replace the camshaft.

Check for heat discoloration, score marks, chipped areas, pitting, and uneven wear.

Excessive clearance necessitates new bearings.

The rear bushing, similar to a camshaft bearing, must be installed by a machine shop with the proper tools and alignment.