GMC 12698945 Valve Lifter

Bear in mind also that if the camshaft is being replaced, the Lash Adjusters should also be new ones and should not be reused on the new camshaft. First, and ideally the first thing you do before working near the top side, is to disconnect and remove the intake manifolds, valve covers, rocker arms, pushrods, valley cover or valve Lash Adjuster oil manifold, timing chain, cylinder heads, radiator, air conditioning condenser and camshaft position sensor. Before removing the Lash Adjusters, place them in a box with a label so that they will be easily found during reinstallation. Lift all the retainers and Lash Adjusters carefully and ensure that they are clean then note that a single retainer has four Lash Adjusters and if reused should be placed back in their respective positions. Newer engines, Lash Adjusters may be pulled out with small magnet or bare hands; while older engines may require a tool possibly due to resin-like deposits known as gum and varnish. Pliers should not be used for turning the Lash Adjusters unless the Lash Adjusters themselves are being replaced since such action will damage them. For 5.3L models, unscrew the mounting bolt of the camshaft sensor and take it together with the sensor from the cylinder block, then remove the camshaft retainer plate with attention to its position. Insert three 6-inch long bolts into the camshaft sprocket bolt holes and use it to pull the camshaft out supporting it close to the block area to avoid damaging the bearings. Before installing the camshaft insert a thin layer of assembly lube on the camshaft bearing journals and lobes and mate the camshaft carefully to avoid scratching the bearings. Screw the camshaft so as to align the dowel pin with the 3 o'clock, fit the camshaft thrust plate and torque the bolts to the recommended value whilst making sure the mating surfaces of the gaskets are clean. Fitting of timing chain and sprockets and camshaft position sensor with a new O ring should be installed. Coat the Lash Adjuster with clean engine oil, fit it in the Lash Adjuster retainers such that the flats line properly, and for 2005-on 5.3L the raised surface should fit in the notched area of the retainer. The retainer and Lash Adjusters must be installed as a unit, and when reusing the original Lash Adjusters return them to the same locations in the engine and torque the Lash Adjuster retainer bolts to the factory recommended specifications. The other steps involve the reversal of the above process and before an engine is started the oil should be changed and a new oil filter fitted.