Nissan 13257-V5001 Rocker-Valve

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Remove the valve covers. Loosen the rocker arm shaft retaining bolts a little at a time to avoid distorting the shaft, working from the ends toward the middle of the shafts. Some of the valves will be open when you loosen the rocker arm shaft bolts and the rocker arm shafts will be under a certain amount of valve spring pressure. Therefore, the bolts must be loosened gradually. Loosening a bolt all at once near a rocker arm under spring pressure could distort the rocker arm shaft. Prior to removal, scribe or paint identifying marks on the rockers to ensure they will be installed in their original locations. Remove the bolts and lift off the rocker arm shaft assemblies one at a time. Lay them down on a nearby workbench in the same relationship to each other that they're in when installed. They must be reinstalled on the same cylinder head. Note that the shafts with the larger notches go on the intake manifold side. Check the rocker arms and shafts for abnormal wear, pits, galling, score marks and rough spots. Don't attempt to restore rocker arms by grinding the pad surfaces. Measure the outside diameter of the rocker arm shaft at each rocker arm journal. Compare the measurements to the specific rocker arm shaft outside diameter. Measure the inside diameter of each rocker arm with either an inside micrometer or a dial caliper. Compare the measurements to the specific rocker arm bore diameter. Subtract the outside diameter of each rocker arm shaft journal from the corresponding rocker arm bore diameter to compute the clearance between the rocker arm shaft and the rocker arm. Compare the measurements to the specific clearance. If any of them fall outside the specified limits, replace either the rocker arms or the shaft, or both. Installation is the reverse of the removal procedure. Tighten the rocker arm shaft retaining bolts, in several steps, to the specific torque. Work from the ends of the shafts toward the middle.

To remove the valve covers begin with easing the rocker arm shaft retaining bolt in stages, at least two or three times with a small interval in order not to bend the shaft and starting from the outermost bolts. Some of the valves will still be open and the rocker arm shafts will be under spring tension, therefore do not undo any bolt entirely near a rocker arm under tension. Before you remove them you want to label each of the rockers for the specific part of the engine they were located at, so for instance if it was an FI rocker it would be marked Fl for Front Intake and if it was FE it then would be marked Front Exhaust. Unbolt and take off the rocker arm shaft assemblies one at a time and put them on a work bench in the order they were removed, make sure the shaft's with bigger notches are on the intake manifold side. To inspect, observe the Conditions of the rocker arms and shafts and get the measurement of the outside diameter of rocker arm shaft at each journal with the revised diameter. Check each rocker arm bore to the shaft and record the ID of each rocker arm; calculate the clearance by subtracting the shaft diameter from the bore diameter, and the clearance should be within the specified figures. When the values in the said equations are beyond the limit, the rocker arms and shafts have to be replaced. To install, reverse the removal process and tighten the rocker arm shaft retaining bolt serially in equal turns starting from the two adjacent bolt ends.

Remove the valve covers. Loosen the rocker arm shaft retaining bolts a little at a time to avoid distorting the shaft, working from the ends toward the middle of the shafts. Some of the valves will be open when you loosen the rocker arm shaft bolts and the rocker arm shafts will be under a certain amount of valve spring pressure. Therefore, the bolts must be loosened gradually. Loosening a bolt all at once near a rocker arm under spring pressure could distort the rocker arm shaft. Prior to removal, scribe or paint identifying marks on the rockers to ensure they will be installed in their original locations. Remove the bolts and lift off the rocker arm shaft assemblies one at a time. Lay them down on a nearby workbench in the same relationship to each other that they're in when installed. They must be reinstalled on the same cylinder head. Note that the shafts with the larger notches go on the intake manifold side. Check the rocker arms and shafts for abnormal wear, pits, galling, score marks and rough spots. Don't attempt to restore rocker arms by grinding the pad surfaces. Measure the outside diameter of the rocker arm shaft at each rocker arm journal. Compare the measurements to the specific rocker arm shaft outside diameter. Measure the inside diameter of each rocker arm with either an inside micrometer or a dial caliper. Compare the measurements to the specific rocker arm bore diameter. Subtract the outside diameter of each rocker arm shaft journal from the corresponding rocker arm bore diameter to compute the clearance between the rocker arm shaft and the rocker arm. Compare the measurements to the specific clearance. If any of them fall outside the specified limits, replace either the rocker arms or the shaft, or both. Installation is the reverse of the removal procedure. Tighten the rocker arm shaft retaining bolts, in several steps, to the specific torque. Work from the ends of the shafts toward the middle.

Remove the valve covers. Loosen the rocker arm shaft retaining bolts a little at a time to avoid distorting the shaft, working from the ends toward the middle of the shafts. Some of the valves will be open when you loosen the rocker arm shaft bolts and the rocker arm shafts will be under a certain amount of valve spring pressure. Therefore, the bolts must be loosened gradually. Loosening a bolt all at once near a rocker arm under spring pressure could distort the rocker arm shaft. Prior to removal, scribe or paint identifying marks on the rockers to ensure they will be installed in their original locations. Remove the bolts and lift off the rocker arm shaft assemblies one at a time. Lay them down on a nearby workbench in the same relationship to each other that they're in when installed. They must be reinstalled on the same cylinder head. Note that the shafts with the larger notches go on the intake manifold side. Check the rocker arms and shafts for abnormal wear, pits, galling, score marks and rough spots. Don't attempt to restore rocker arms by grinding the pad surfaces. Measure the outside diameter of the rocker arm shaft at each rocker arm journal. Compare the measurements to the specific rocker arm shaft outside diameter. Measure the inside diameter of each rocker arm with either an inside micrometer or a dial caliper. Compare the measurements to the specific rocker arm bore diameter. Subtract the outside diameter of each rocker arm shaft journal from the corresponding rocker arm bore diameter to compute the clearance between the rocker arm shaft and the rocker arm. Compare the measurements to the specific clearance. If any of them fall outside the specified limits, replace either the rocker arms or the shaft, or both. Installation is the reverse of the removal procedure. Tighten the rocker arm shaft retaining bolts, in several steps, to the specific torque. Work from the ends of the shafts toward the middle.

To remove the valve covers, first loosen the rocker arm shaft retaining bolts gradually to avoid distorting the shaft, working from the ends toward the middle in two or three stages. Before removal, mark the rockers to identify their original locations, using markings such as Fl for Front Intake and FE for Front Exhaust. Remove the bolts and lift off the rocker arm shaft assemblies one at a time, laying them on a nearby workbench in the same arrangement as when installed, ensuring that the shafts with larger notches are positioned on the intake manifold side. Inspect the rocker arms and shafts for abnormal wear, pits, galling, score marks, and rough spots, avoiding attempts to restore rocker arms by grinding the pad surfaces. Measure the outside diameter of the rocker arm shaft at each journal and compare these measurements to the specified outside diameter. Measure the inside diameter of each rocker arm using an inside micrometer or dial caliper, subtracting the corresponding rocker arm shaft diameter to obtain the clearance, and compare the results to the specified bore diameter. Calculate the clearance between the rocker arm shaft and the rocker arm by subtracting the outside diameter of each shaft journal from the corresponding bore diameter, ensuring that all measurements fall within specified limits; if any do not, replace the rocker arms or shaft as necessary. For installation, reverse the removal procedure and tighten the rocker arm shaft retaining bolts in several steps, working from the ends toward the middle.