the_supernerd

I have an '88 pickup that is ticking around 2000 RPMs and it is coming from the valve train. I think I have it narrowed down to the rocker arm assembly, and I am wondering if I can change it without removing the head. I did a little reading on it, and it seems to be possible but not the best way. Has anyone changed their rocker arms without removing the head? Was it successful or did it cause problems later?

I know that I am suppose to use new rocker arms with a new cam, but is it ok to put in used rocker arms with my current used cam?

One more question:
Would worn adjusting screws cause a tick at 2000 RPMs? I would assume bad adjusting screws would make more of a tick at idle.

Matt16

Make sure its not the timing chain, I had mine go after I heard valve train noise. Sorry, can't help with your question directly.

MMA_Alex

bad adjusters are gunna mean the adjustment can be off, which could be noise at any point. You're sure the valve lash is adjusted right?

the_supernerd

The valve lash is adjusted correctly and I just installed a new timing chain with a steel guide. When I got the truck, the valves were out of adjustment and it made a similar noise but throughout the entire RPM range and was very noticable at itdle. Now it seems to be quiet at idle, makes noise at around 2000-2500 RPMs, then gets quiet again. It does not change with load, so I doubt it is anything in the bottom end. I checked it with a mechanic's stethescope and the noise is loudest on the intake side valve cover bolt above the #4 cylinder.

ovrrdrive

To pull the rockers you have to pull all of the head bolts and if you do that and try to lift the rocker assembly off you're just asking to unseat the head. I've seen people change cams and rockers before without pulling the head successfully so it can be done, but with my luck I think I'd just go ahead and do a new head gasket while I was at it. And of course, if you're going that far why not a hopped up cam and a new rocker arm assembly from engnbldr while you're at it?

The adjusters can definitely make a noise but I have no idea at what rpm range. Why don't you email Ted at engnbldr and ask him?

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

the_supernerd

Thanks Ted, that is some good information. I will go check it out.