Originally Posted by engnbldr

>>>*The rocker arm assembly on these engines has several places that can cause noise. The obvious is the pad, note that often we will see a small groove develop on the inner side of the pad. This is caused by the lobe shape at peak lift. If not excessive, the pad can simply be refaced and the arm returned to service.

The end of the adjuster screws move back and forth across the valve tip and over time an hourglass shape will develop. Then attempting to adjust the lash relocates that shape and we then have noisy operation. Plus we can see fractures develop in the end of the screw from loading, if allowed to continue we see damage to the valve tippet.

One overlooked point is the threads in the arm, over many thousands of miles the valve side of those screw holes can loosen. Then we can see the screw itself break right at the lockdown nut seat from side loading. Run the screw in halfway from the bottom side and try to work it back and forth, if you can, replace the arm. We use a small wire brush on the end of a drill, a couple of strokes cleans the threads and this is helpful for installation. Never try to tap those threads, it doesn't work.

Another source of noise is the bottom side of the rocker shaft itself, it is common to see a lot of wear there. If present, accurate adjustment is impossible, the shafts will need to be replaced.

Some of these engines have so many miles on them we are now seeing a few rocker arms with the shaft housing bore worn, just a few years ago this almost never happened. This is easy to check for, slide the arm on a known sound shaft and try to rock it, some motion is acceptable of course but if very loose, replacement of the arm is the only solution.

We bite the bullet and buy Toyota only when arm replacement is required, otherwise we just recondition them and put them back on. A good used or reconditioned arm is just as good as a new one....*EB