Alright, I will start off saying I'm not super engine savvy, but my dad is, however he's not internet savvy, so you have me to deal with online!

Anyways, we just purchased this 1998 3.8l V6 camaro with 140,000 miles on it. We knew the heads were possibly blown at the time, but we purchased anyways because dad said he could fix it. Anyways, we stripped it down and took the heads into a machine shop, an they only had to file down a tiny spot on them and they said they were fine. We cleaned everything else up while we were in there, replaced all the gaskets and put it back together. It has aftermarket pacesetter headers on it as well.

The engine makes this knocking, dad thinks it's a stuck lifter (I say collapsed if it is a lifter). We drained a bit of oil out of it yesterday and replaced it with a thinner oil, but it's still ticking/knocking. It doesn't appear to have any power loss, except very occasionally when you lay into the gas it will bog down a bit. The sound also lessons as you increase rpm's. If you are out on the highway and get up to cruising speed (65-70) and let off, it pretty much goes away, but will come right back when you press the gas again, just not as loud as when a idle.

So, I'm just looking for a list of things to start checking off and how to do it before removing the head again. I've seen things anywhere from checking the MAF, the flexplate, and torque converter belts.

Here's a vid as well:

Camaro knock - YouTube

 

Can't really tell where the noise is coming from as the speakers on my PC don't have much fidelity. Could be a valve train problem, but I am concerned by your mentioning that the noise changes with engine load, as this could indicate a bearing problem. I suggest you first verify there are no valve train problems. Buy a $15 mechanics stethoscope and probe about the engine to locate the noise source. You could also remove the valve covers and with the engine idling place a finger tip on top of each valve stem, the one making noise will give your finger a sharp rap whenever the valve is being opened. Be careful of the hot oil being slung about. By the way, how is the oil pressure? SES lamp lit?

 

Oil pressure is fine, and there are no lights lit indicating any issues.

 

that sounds more like a poorly adjusted rocker pull off the valve covers and make sure none of the rockers are loose (lifters are usually quieter than that and have more of a ticking sound than a clicking sound)

 

What other kinds of symptoms would I have if it were a loose rocker?

 

I think your dad is right with the lifter. You can try some sea foam as and oil additive. Run the car for a couple of hours then change the oil to Mobil one and try a mobil one or other high end filter. Then i would try to see if it comes around in a few hours. Your car has probably sat for a awhile and has little pc of carbon floating around in it. Since your lifters are not adjustable your going to have to replave the lifter if the cleaning does not work.

(most parts stores carry this)
Sea Foam | Motor Treatment | General Content - Motor Treatment

 

I forgot to mention it does sputter on occasion too. Could a loose header be a problem for the knocking and the sputtering?

 

In the video it sounded like a metalic impact sound. A leak would sound more like a pop. Videos can mess up the sounds. Leaking header would not cause any running issues unless it was so bad it was letting in oxygen and screwing up the O2 sensor readings but even then it would not be a sputter.

Have the car scanned at a parts store to see if there are any codes..

 

It's definitely more a metallic sound. I talked to dad again, and he said maybe this weekend we will check the rockers and that stuff. He put some Rislon in the oil, and I need to put some miles on it to see if that helps any. I was just wanting other ideas to chase down that didn't include the lifters or rods just in case.

 

So we're thinking about replacing all the lifters and the rods, will we have to replace all the gaskets again to do this?

Also, any recommendations on lifters/rods and where to purchase?