To determine the extent of cam lobe wear, the lobe lift should be checked prior to camshaft removal by first removing the valve cover. Position the number one piston at TDC on the compression stroke. Beginning with the number one cylinder valves, mount a dial indicator on the engine and position the plunger against the top surface of the first rocker arm, ensuring it is directly above and in line with the pushrod. Zero the dial indicator, then slowly turn the crankshaft in the normal direction of rotation until the indicator needle stops and begins to move in the opposite direction; the point at which it stops indicates maximum cam lobe lift. Record this figure for future reference, then reposition the piston at TDC on the compression stroke. Move the dial indicator to the remaining number one cylinder rocker arm and repeat the check, recording the results for each valve. Continue this process for the remaining valves, ensuring each piston is at TDC on the compression stroke while following the firing order sequence. After completing the checks, compare the results to the specifications; if camshaft lobe lift is less than specified, cam lobe wear has occurred, necessitating the installation of a new camshaft. After removing the camshaft from the engine, inspect it for uneven wear, pitting, and evidence of seizure. If the journals are damaged, the bearing inserts in the block are likely damaged as well, requiring replacement of both the camshaft and bearings. If the bearing journals are in good condition, measure them with a micrometer and record the measurements, checking each journal at several locations around its circumference to identify any out-of-round conditions. Check the inside diameter of each camshaft bearing with a telescoping gauge and measure the gauge with a micrometer, subtracting each cam journal diameter from the corresponding camshaft bearing inside diameter to obtain the bearing oil clearance, which should be compared to specifications; excessive clearance necessitates new bearings installed by an automotive machine shop. Inspect the distributor drive gear for wear and replace the camshaft if the gear is worn. Additionally, inspect the camshaft lobes, including the fuel pump lobe on carburetor-equipped models, for heat discoloration, score marks, chipped areas, pitting, and uneven wear, measuring the camshaft lobe height with a micrometer; if the lobes are in good condition and the lobe height measurements are as specified, the camshaft can be reused. Camshaft bearing replacement requires special tools and expertise, so it is advisable to take the engine block to an automotive machine shop to ensure the job is done correctly.
Posted by ToyotaPartsDeal Specialist 
