GM 17120070 Valve Lifter

There are various methods that can be employed to diagnose a noisy Lash Adjuster. To start with, you can listen at the other side near the valve locations using a mechanic's stethoscope or a length of hose while the engine is idling in order to locate a noisy Lash Adjuster. Another way involves removal of the rocker arm cover and touching each valve spring retainer one at a time with an idling engine. If one of the Lash Adjusters is bad, you will feel a noticeable shock in the retainer every time the valve seats. Some common causes for noisy Lash Adjusters include dirt in the Lash Adjuster and problems related to oil flow, viscosity or pressure. There are few things that need to be done before making any conclusions about the problematic Lash Adjusters. Firstly, it is necessary to inspect the engine oil for fuel contamination; ensure that it's at proper level; clean and with proper viscosity. For removal, start by removing intake manifold and rocker arm cover(s). After that remove rocker arms and pushrods. If your engine has roller Lash Adjusters (1994 and newer models), also remove lifter guide. Different methods can be used to get out the Lash Adjusters from their bores. However, in some cases, you may not have to use this special tool made for this purpose. In newer engines without significant varnish buildup, Lash Adjusters can often be removed using a small magnet or even your fingers. Use a machinist's scribe with one end bent as an alternative method of pulling them out by placing its point under the retainer ring on top of each Lash Adjuster. Lash Adjuster removal should avoid using pliers unless they will be replaced as pliers can damage precision machined and hardened Lash Adjusters.Try not to forget that before removing them carefully place them in a well labeled container to make sure that they are reinstalled in their original positions later on since some engines may have both standard and 0.010-inch oversize Lash Adjusters installed at the factory, which are marked by a drop of white paint and a 0.25 (mm) OS stamp on them. As for inspection and installation, you should remember that Lash Adjuster parts cannot be sold separately. The Lash Adjusters have to be replaced with new ones if they are worn out; in case you have conventional Lash Adjusters in your engine, camshaft should also be replaced. It is important never to mix used conventional Lash Adjusters with a new camshaft or new conventional Lash Adjusters with a used camshaft. Nevertheless, used roller Lash Adjusters can be reinstalled with a new camshaft, and the original camshaft can be used if new roller Lash Adjusters are installed provided that the used parts are in good condition. Whenever you are reinstalling used Lash Adjusters ensure that they are put back to their original bores, soak new Lash Adjusters in oil to release any air pockets trapped within them, also coat all Lash Adjuster bottoms with moly-base grease or engine assembly lube prior to installing them. Remaining installation steps must now be done in reverse order while for those installing roller Lash Adjusters make sure the lifter guide bolts are properly tightened. Lastly start up the engine and look out for any oil leaks.