Chevrolet 17120070 Lifter,Valve

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.

A noisy valve lifter can be identified during idling by using a length of hose placed near each valve and listening at the hose's other end. Alternatively, you can remove the rocker arm cover and place a finger on each valve spring retainer, one at a time, while the engine idles. If a defective lifter is present, the shock felt as the valve seats will reveal it. This noise is often caused by trapped dirt inside the lifter.

Store the lifters in a labeled box to ensure they are reinstalled in their original locations.

After removing the lifters, you should clean them and inspect them for scuffing, score marks, and uneven wear. Additionally, check the rollers for wear and damage. Replace the lifters if necessary.

The remaining installation steps follow the reverse order of removal. After everything is reassembled, run the engine to check for oil leaks.

Lubricate the lifters with clean engine oil and install them in the retainers, ensuring proper alignment. Tighten the lifter retainer bolts to the specified torque.

Next, take out the bolts holding the roller lifter guide to the block and remove the two guides, marking them for their original sides.

Install the camshaft bearing caps, tighten the bolts in steps, and slide the camshaft sprockets and timing chain toward the camshafts, aligning the slots with the projections on the sprockets.

If any camshaft journal diameter falls below the specified value, it is necessary to replace the camshaft.

It is important to keep all lifters separated and identified for reinstallation. After cleaning each lifter individually, inspect for any nicks or gauges, as any damage necessitates replacement.

A noisy valve lifter can be isolated while the engine is idling by using a mechanic's stethoscope or a length of hose near each valve location, listening at the other end. Alternatively, you can remove the valve cover and touch each valve spring retainer one at a time to feel for shock if a lifter is defective.

If reusing lifters, install them in their original bores, coating them with moly-base grease or engine assembly lube, and lubricate the bearing surfaces of the lifter bores with engine oil.

The procedure is essentially the same, but there is no pushrod cover to remove in this case.

Earlier models have conventional lifters, while later engines feature roller lifters, which are secured by a guide plate and lifter guides that must be removed to access the lifters.