If a camshaft is being replaced, then the Lash Adjusters should also be replaced; they are not expensive and will help in preventing future problems. In particular, expired Lash Adjusters should not be used with a new camshaft. Start by loosening the engine from the vehicle, followed by the removal of the valve covers and the intake manifold. Subsequently, the rocker arms as well as the pushrods should be removed, and after this, the timing chain and sprockets, and finally the cylinder heads. Before removing the Lash Adjusters, plan where to put them, then place them in a box marked or separated in such a way that when doing the replacement, you know where they came from. Pull off the Lash Adjuster retainers and Lash Adjusters and keep them in a clean place; each of the retainers contains 4 Lash Adjuster nozzles that must be refitted if the retainers are to be reused. Do not pull the camshaft with the Lash Adjusters in place. If the Lash Adjusters are built up with gum and varnish, they may be liable to require the use of some mechanical means for their removal, although, for example, a small magnet or the fingers of one hand may suffice in many cases. It is recommended not to use pliers on the Lash Adjusters if planning to replace them because the usage can badly affect them. Take out the bolts and the camshaft retainer plate with attention to the orientation and then insert a new bolt into the camshaft sprocket bolt hole to facilitate whenever it is to be withdrawn. Slowly instruct the camshaft to be pulled out, and while doing this, the camshaft should be supported near the block part in order to avoid carrying out excessive pressures on the bearings. Camshaft lobe height and camshaft base circle also need to be measured to calculate the lobe lift, the actual figures of which need to be recorded for future use. In the case where the lobe lift is less compared to the specified value, installation of a new camshaft is recommended. Following the cleaning of the camshaft, smooth the bearing journals that are always susceptible to wear and damage; if damaged, it will require renovating both the camshaft and bearings. Using a micrometer, measure the bearing journals to ascertain if the latter are worn out. As for the camshaft, the lobes of the camshaft must be checked for discoloration and wear; if they pass the inspection, the camshaft can be reused. Always withdraw the Lash Adjusters and clean them, and if the Lash Adjuster walls are worn, the corresponding Lash Adjuster bores will also be damaged. Check that the rollers are rotating with certain looseness if required, but not too loose. Roller Lash Adjusters, when used, cannot be returned to the engine with a new camshaft and thus should always be purchased new with the camshaft. Coat the camshaft bearing journals and lobes with assembly lube before installing the camshaft in the engine, whilst supporting it close to the block. Swivel the camshaft in order to line up the dowel pin in the intended position, place in the thrust plate, and fasten the bolts to the appropriate torque limit. I reinstall the timing chain and sprockets, adjust the camshaft position sensor employing a new O-ring. Dip the Lash Adjusters into fresh engine oil and fit them into the retainers, making sure that they are correctly positioned. Loosen the Lash Adjuster retainer bolts slightly, then use your wrench to tighten the retainer bolts to the recommended number of turns. To finish the installation, a mechanic should follow the removal instructions in reverse, and before starting the engine, the cooling system should be replenished with liquid, the oil should be changed, as well as the oil filter.
Posted by GMPartsGiant Specialist