Chevrolet Repair: chirping noise

Question
I have a 2004 Chevy Impala LS 3.8L with 190,000 miles. There is a chirping noise coming from engine, so I used a long stick of wood to locate noise. It sounds like it's coming from waterpump, so I removed the serpentine belt and the noise is still there. I am the original owner and have maintained my car religously. What do you think might be the problem, and how much should I expect to pay?

Answer
That's a push rod engine. If you have narrowed the location down to the area of the water pump, and that's with the pump deactivated, there are only so many other possibilities......          Because the crank is fairly close in proximity, I'd e have a close look at the harmonic balancer and pulley. Check for any play, and for interference at the rotating assembly, like scratches on the timing cover. Check the balancer for integrity at rubber damper. If all looks normal, then I would assume the timing chain has too much slack and is rattling, inside, against the timing cover. Something is afoul under that cover;a guide or the like. It's difficult to check the slackness of the chain physically on this engine without the learned sensitivity one only gets from years of experience.You cant just pull the distributor cap and watch the rotor as you turn crank for and aft. You may be able to deduce that it's a chain, if you get specs on valve events[valve timing] and check if you are in time relative to crank angle, but by the time you do that, it would be fair to assume, that you could already have the timing cover off, and have access to the possible offending components.