I have a 2003 base model Impala with a little over 130k on it that is experiencing some distinct knocking.

What I notice is the knocking sounds like metal on metal, gets worse as engine runs (in idle, stationary), reduced power (low idle), and oil level is not affected when shut off and oil level is checked/double checked.

Car ran fine until today although I did notice it sputtering a bit and threatening to die slightly but thought an injector cleaner could help, wrong! LOL

I am guessing oil pump but there are a few facts that bother me about this theory. First, oil currently in the car is 5w-30 castrol full synthetic, purelator filter, just changed it a few weeks ago, still golden color. NO oil warning message of any kind displays in the message center. I have never even seen it. Had this car for two years. One other aspect that I notice is a friend told me to see what the message center displays when not running, but in AC (key in ignition just before start position) and the check engine light comes on solid and does not turn off.

The same friend also told me to manually check oil pressure before jumping to conclusions by going up to a local parts store and getting an oil pressure gauge.

I figured I would get a thread started so by the time I check the oil pressure tomorrow maybe I might have some replies or a reply.

My poor car, I don't even want to start it the knocking is so aggressive but I kind of have to if I want to check the oil pressure.

Any other suggestions/advice?

I am not the most experienced with cars, you may have to be a little clearer with your responses should you choose to.

 

Update:
I think I have eliminated the oil pump.

Went up to my local auto parts store and borrowed a diagnostic computer. Pulled code P0300, random misfire. The readout also listed a few other possibilities of where the problem could be coming from such as EGR valve, catalytic converter, O2 sensor, injectors, spark plugs and a few others I can't remember off hand.

I pulled the EGR valve. The plunger inside looks to be down. Unit is very corroded and filled with what I am told is carbon buildup. I bought some carbon cleaner and am currently soaking overnight to clean it out. A quick shake of the unit yielded no rattling whatsoever although I was told this is not the most reliable test.

I am hoping the plunger is just stuck and the soaking will loosen it. If that doesn't work, looks like I will be pulling all the plugs. After that, I need a mechanic. lol