Have a loud tapping coming from front bank valve cover. Late production 3.1 liter (roller rockers). How can I tell if it's rocker or deeper from within? I have pulled the rockers and inspected for obvious cracks/wear. Tapping seems to lesson after engine reaches normal temp, but never goes completely away.

I can tell you and you can research it on this site, but it is a common problem with engines over 100k miles. My car actually had collapsed lifters, and it ran real bad. Someone suggested putting kerosen in the oil to loosen up any sludge. It did work for a while, but in the end I replaced the lifters. Cost about $10.00 ea, you can find them on the internet. While you are at it, you can fix another common Chevy problem, coolant leaks from the intake gasket. Total repair time for a first timer is about 6-8 hours. I recommend you get some old cardboard boxes and make drawings where the bolts go. Another real issue is that you MUST put the push rods back in their original position. The lengths are different for intake and exhaust.

You might have a broken camshaft.I have seen two or three broke in half.Pull the oil pump drive and have someone turn the crankshaft with a 15mm socket on a ratchet.Look down the hole where the oil pump drive goes into.If you seen it not turn,the camshaft is broken.If you want to know the fix,another engine and eats up the cam bearings.

Forgive me if i'm wrong here, but if the cam was broken, i dont think the car would run. I know this is unrelated, but a friend of mine owns an olds alero, I know a completly different car, but it was tapping something terrible also, and he ripped it completly down, found nothing, put it back together, and still, tap tap tap tap, ended up being, get this, the water pump. Yes, the bearings in the water pump went out, and were causing the tapping. You say the noise sounds like its coming from the front valve cover area? Thats where the waterpump is located isnt it? Might be worth a shot. Um, maybe take the valve cover off, and start the motor, if the tapping gets louder with it off, chances are it is a valve, or something deeper.

Did you figure it out?

This tapping can also be the famous piston slap, sometimes it can fool you, ordinarily though it would satrt at a much lower mileage. If this engine is sludged up to the point you can see it with the v/c off, this is bad. You may want to check the oil pressure with a mechanical gage to see if you have a deeper problem.

An easier way to see if it's the water pump, I doubt it is, but just remove the serpentine belt start the car and run it for no more than a minuit. You should hear the diffeence in less than that, if it's the water pump.