Mercury D4FZ-6261-C Bearing - Camshaft

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To inspect the camshaft, measure the major and minor diameters of each cam lobe to determine the lobe lift, and if it is 0.005-inch less than specified, replace the camshaft and all lifters or followers. After removing the camshaft, clean it with solvent and inspect the bearing journals for uneven wear, pitting, or signs of seizure; if damaged, both the camshaft and bearings need replacement. Measure the camshaft bearing journals with a micrometer, and if they are more than 0.001-inch out-of-round, replace the camshaft. Check the camshaft lobes for heat discoloration, scoring, chipping, pitting, and uneven wear; if they are in good condition and the lobe lift measurements are as specified, the camshaft can be reused. For lifter inspection, clean the lifters thoroughly and ensure the roller on each turns freely without wear, checking the pushrod seat for wear and fit in the original bore. Press down on the plunger to confirm it operates freely; if lifters show wear or binding, replace them as a complete set along with the camshaft. When installing new lifters, a new camshaft must also be installed, and used lifters should only be installed with the original camshaft in their original locations. Camshaft bearing replacement requires special tools and expertise, so it is advisable to take the block or head to an automotive machine shop for proper handling.

To check camshaft lobe lift and see how much its wear, unbolt the valve covers and the rocker arms and leave the push rods installed. Remove the number one piston and place it at Top Dead Centre on the compression stroke, then install a dial gauge on the engine so that it is facing the first push rod. Depress the dial indicator and start rotating the crankshaft slowly counterclockwise and stop at the point where the needle stops showing more readings and then starts to decrease noting the maximum cam lobe lift. Take this measurement and move the piston to TDC and do this for all the valves in the same firing order with the piston on the compression stroke. Finally, after performing the checks, refer to the corresponding specifications; if the measure of the lobe lift is under the required value, then it means wear and as a result a new camshaft will be needed. For removal, get off the pushrods, valve lifters, timing chain, as well as the camshaft sprocket; one must consider if the radiator or air conditioning condenser needs to come off. Take out the bolts of the camshaft thrust plate and check the thrust plate for signs of wear, if it is worn you replace it. Using the cam sprocket bolt turn it partially to act as a handle and slowly push the camshaft out without scratching the lobes against the bearings. After removal, camshaft should be cleaned and checked for damage and wear on bearing journals; if they are damaged, both camshaft and bearing will have to be replaced and it can only be done using special tools and equipment. Check the camshaft lobes for damage or discoloration, if they are still okay, the bearing journals should be used to measure for excessive wearing and thus the camshaft can be again used. The camshaft should be lubricated with grease or assembly lube before it was installed, and inserted into the engine with the help of a follower to prevent any bearing damage. Make sure that the Woodruff key is correctly positioned before it is fitted; grease the thrust plate and when it is fitted, ensure that the grooves are facing inwards. Put in the timing chain and sprockets then using clean oil lubricate the lifters before reinstalling them. The final part of the fixing process is based on step-by-step reversing of the exclusion acts, and before the engine turn on, replace the oil and oil filter.

To verify camshaft lobe lift and to see how much they have been worn out then the rocker arm covers and rocker arms have to be removed but the pushrods have to remain on. Where the top dead center TDC on the compression stroke and then secure a dial indicator on the engine in a way that the plunger of the indicator rests upon the first pushrod. Rotate the crankshaft until the contact of the dial indicator is broken and then turn the crankshaft in the opposite direction until the tip of the indicator jumps out of scale and take the maximal cam lobe lift. With this figure recorded reposition the piston at TDC then move the dial indicator to the next pushrod and do the check over the other valves and remember it is cylinder to cylinder, firing order wise. After the checks are done, compare the readings with the specifications; when camshaft lobe lift figure is lower than the specified value, one gets to see that the engine has worn out and therefore is expected to replace the camshaft. For removal, removal of pushrods, valve lifters, timing chain as well as the camshaft sprocket before checking the V8 engine camshaft end play with the aid of a dial indicator as well as replacement of the thrust plate if needed. Slowly and gently lift the camshaft out and be sure to steady it in order not to harm the bearings. For inspection, it is recommended to follow the procedure for the camshaft and the bearings inspection together with the roller and the conventional lifters' inspection. Bearings head of camshaft can be replaced only with special tools and should be done only at an automotive machine workshop. For installation, drop the camshaft lubing its bearing journals and lobes, slid the camshaft into the engine while supporting it, apply grease to the thrust plate, place the thrust plate at the block prior to tightening the bolts. Lastly fit the lifters, pushrods, rocker arms, timing chain/sprocket, timing chain cover and the rocker arm covers in the reverse manner you removed them and the last step is to change the oil with a new filter before starting the engine.

To check camshaft lobe lift and see how much its wear, unbolt the valve covers and the rocker arms and leave the push rods installed. Remove the number one piston and place it at Top Dead Centre on the compression stroke, then install a dial gauge on the engine so that it is facing the first push rod. Depress the dial indicator and start rotating the crankshaft slowly counterclockwise and stop at the point where the needle stops showing more readings and then starts to decrease noting the maximum cam lobe lift. Take this measurement and move the piston to TDC and do this for all the valves in the same firing order with the piston on the compression stroke. Finally, after performing the checks, refer to the corresponding specifications; if the measure of the lobe lift is under the required value, then it means wear and as a result a new camshaft will be needed. For removal, get off the pushrods, valve lifters, timing chain, as well as the camshaft sprocket; one must consider if the radiator or air conditioning condenser needs to come off. Take out the bolts of the camshaft thrust plate and check the thrust plate for signs of wear, if it is worn you replace it. Using the cam sprocket bolt turn it partially to act as a handle and slowly push the camshaft out without scratching the lobes against the bearings. After removal, camshaft should be cleaned and checked for damage and wear on bearing journals; if they are damaged, both camshaft and bearing will have to be replaced and it can only be done using special tools and equipment. Check the camshaft lobes for damage or discoloration, if they are still okay, the bearing journals should be used to measure for excessive wearing and thus the camshaft can be again used. The camshaft should be lubricated with grease or assembly lube before it was installed, and inserted into the engine with the help of a follower to prevent any bearing damage. Make sure that the Woodruff key is correctly positioned before it is fitted; grease the thrust plate and when it is fitted, ensure that the grooves are facing inwards. Put in the timing chain and sprockets then using clean oil lubricate the lifters before reinstalling them. The final part of the fixing process is based on step-by-step reversing of the exclusion acts, and before the engine turn on, replace the oil and oil filter.