Since it's started getting colder, my truck's been making a fast "clicking" noise from somewhere under the hood. It sounds like it's near the top of the engine, but I'm not sure. It varies with RPM, and gets slightly quieter when the engine warms up but never goes away. Occasionally when it's real cold or the truck has been sitting a long time, I'll get a loud lifter ticking for a little while, and this is not the same sound; it's more high-pitched and "sharper." The noise seems to go away when I'm going up a hill, and get louder when I'm compression braking down the other side. It's sometimes not noticable at idle, and sometimes there but not real loud at idle.

It did this last winter, too, but I just ignored it. Now I want to fix it. It's also somewhat intermittent, but usually does make the noise.

Anybody got any thoughts on what I should look for? I'm guessing something in the valvetrain, so how hard is it to pull the valve cover? Looks like I just need to take the TB off and it should come off, but I've never done that before...

 

It's not too bad to get it off, just get a new gasket (as well as one for the throttle body) before you start.

These engines are known for a couple of problems in the valvetrain. Sticking lifters is one, which of course causes the rocker to have too much lash and makes a good bit of noise. Another common problem is bad cam bearings, often caused by overtightening of the cam belt which can eat up the front bearing. The oil passages in the head supplying oil to the cam and valvetrain are a bit on the small side and can get clogged with gunk over time, also causing noise and wear due to lack of lubrication.

 

Sounds like you agree it's probably in the valvetrain, right?

So, uh, once I get the cover off, how do I tell what my actual problem is? I've never been inside a OHV engine, never mind an OHC... (Dug into a Model A flathead once, and a few small engines, but they're pretty different.)