GMC 12681275 Arm Assembly, Exhaust Valve Rocker

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Removing of valve covers from the cylinder heads is to be done by first of all removing one at a time each Rocker Arm Pivot Bolt and taking out the rocker arms, bolts and pivot support pedestal. Keep track of their positions and store them separately. Proceed by removing the pushrods, keeping them in sequence as they are. Each rocker arm has to be checked for wear, cracks, damage as well as binding and roughness of the pivot bearings during inspection. The rocker arm has to be replaced if its bearings are worn or damaged. Also examine the rocker arm pivot support pedestal for any cracks. Make sure that all the pushrods are open at the hole on each of their rocker arms' ends and check them for fractures, large amounts of wear or obstruction in oil holes. After lubricating them with clean engine oil or assembly lube, put back the push rods exactly where they came from. In order to protect the stems of valve along with pushrod ends from damage apply some engine assembly lube on them. For every rocker arm shaft as well as bearing make sure you apply clean engine oil then install loosely into original locations (where they were removed). Rotate crankshaft to TDC on compression stroke for number 1 piston then tighten intake valve rocker arms for specific cylinders. Rotate crankshaft 360 degrees then tighten intake valve rocker arms on other cylinders. At last put on valve covers start engine and listen for unusual noise coming from valve train and to check for oil leaks.

You can start by removing the rocker arms, which will be loosened and stored in containers labeled as rocker arm support bars. Keep their different pushrods separately. If necessary, inspect each rocker arm for damage on the pivoting area and cracks or wear on the bearing surface; after that replace any defective ones, making sure roller bearings rotate freely. Look at the pushrods to see if they have cracks, are too worn out or bent. For reinstalling, lube the push rods and put them back into their original position with full seating in the lifter being noted. After that, place back the rocker arm support with arrows up and also wipe off grease from valve stems and ends of pushrods. Then fit all rocker arms one by one, lubricating roller bearings lightly and tightening the rocker arm bolts evenly according to a specified torque. Lastly, you can start your engine up and check it for oil leaks or noises from the valve train mechanism.