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4.6 Hydraulic Cam Followers

All gasoline engines, and all diesel engines except 1985 through late 1986, are equipped with hydraulic cam followers which automatically maintain proper valve adjustment. The cylinder head cover label which identifies these engines is shown in Fig. 4-15.

Fig. 4-15. Identifying label found on cylinder head cover of engines with hydraulic cam followers. These engines do not require valve adjustment.

Hydraulic cam followers are pumped up by engine oil pressure, expanding as necessary to fill the gap between valve and camshaft lobe. If the space between the valve and the camshaft lobe becomes smaller, due to wear for example, some oil escapes through a small orifice and the follower bleeds down slightly.

Some valve noise at startup is normal, due to hydraulic cam followers which have bled down while the engine was not running. Before checking noisy cam followers, check to see that the engine oil level is correct and allow a minute or so with the engine running for the lubrication system to properly pump up the cam followers.


After installing new cam followers, the engine should not be started for at least 30 minutes. New cam followers are at full height and must be allowed to bleed down to their proper height. Failure to do this may cause valve or piston damage.

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