Toyota Repair: 1997 T100 Valve Noise, valve clearance, side valve

Question
Ted,I have a 97 T100, 4x4, 5VZFE? engine, 184,000 miles and over the last couple months a tapping noise has developed at around 2600-2800 rpm.  It is coming from the aft drivers side valve cover area.  I used the trusted screwdriver to the ear method to isolate it.  At this point I'm assuming valve adjustment but most of the info out there says the valves rarely if never go out of adjustment.  Is there anything else I should be looking for when I pull the valve cover?  I do have the valve adjusting tool.


Answer
This valve cover is easy to remove and it would be worth to check the valve clearance at the #6 cylinder, yes it's true the valves rarely go out of adjustment but it's still possible, if there is a noise then there is something not tight and the valve clearance would be the first thing to check, if the valve clearance is ok then I would suspect that the may be a broken valve spring, I have seen this a few times. Check the springs by pushing down on the adjuster shim, there's no need to remove the comshafts, the spring that's broken will feel a lot softer than the rest. If the valve clearance is excessive look for a possible camshaft wear problem, if the deviation is minimal, about 0.03 to 0.05" then use the correct shims to take up the excessive clearance.