Valve Lifters

doesn't sound familiar. have you cleaned the egr circuit and intake manifold?

 

The Gen 3 does have hydraulic valve lifters. They adjust their own clearance by having engine oil pumped into them, and they have little check valves to keep the fluid inside so they are stiff enough to open the valves. If one gets leaky, it may make a tapping noise. You can replace it with a new one (or sometimes just clean it well in clean oil and it will work again). There's a test for it in the repair manual, with a little pin-like service tool to push on the check ball.

Just think how much simpler this is than Gen 1 or Gen 2, where the only way to correct valve clearance if it gets off is to buy replacement lifters in different sizes (35 different sizes, and 16 lifters in the engine). Gen 3, there's just one lifter part number (even the same for intake and exhaust side!), and if one is stuck, you clean it or put in a replacement.

Still, I doubt there's any way you can sneak them out and back in without removing the camshafts, so it's a fairly involved operation. You'll want the details in the repair manual.

-Chap

 

I think it calls them valve lash adjusters. The "lash" is another word for the clearance, or the amount of motion that happens before the valve is pushed open. By filling with oil and expanding, the adjusters keep the lash very close to zero, keeping the wasted motion and tapping noises at bay.

Hydraulic lifters, or lash adjusters, are not a new idea; my 1988 Mazda had them, as did a friend's 1965 Ford. A clever thing Toyota has done is put them at the other end of the rocker arm, so their mass does not have to move up and down with the valve. They just sit there.

-Chap