just recently it started this knocking noise. sounds like exhaust pipe hitting metal. it does it all the time hot or cold. dosnt get any louder with rpm. i held the pipe in several spots to see if it would stop.i can hear it the most laying down by the pan. truck has 148k bone stock i use PP 5w30, oil was clean last oil change. i am going to try a topend cleaner and see if it goes away. has great oil psi too

 

Is it consistent with RPM? If not, it may just be one of the cats has broken down. Smack the cats with a rubber mallet with the engine off to see if they rattle. Other possibilities are broken flexplate, bad lifter, etc. Can you get a sound clip? (not a rod knock?)

 

Does it sound like this? Mine did this at random.....meaning it would do it for a few mintues and then quit a few minutes later. Oil pressure was fine and oil was clean when I changed it. It turned out to be the fuel pump going out causing lean knock. No check engine lights ever came on.

Lean Fuel Kock

In the video I mention it seemed to be coming from one side when in actuallity it was coming from EVERYWHERE!

A month later my fuel pump went out while driving. Replaced the fuel pump and it hasn't made a noise since.

 

wow it actually does sound like that but quiter. hopefully its more pronounced because of your headers. ill get a sound clip for good measures when i get back in town tomarrow. ill try and check the fuel pressure aswell. it still runs great for a stock truck but you never know

 

It sounds louder in the video. I took the video with my iPod Nano so its a little small and shakes around easy. Does yours go away and come back at random?

 

Well still havnt been able to get a vid noise is still there I work nights so I am going to try on my day off to shoot a vid. When it sits over night it takes about 7 seconds to start knocking and I would Like to get that on the camera. Noise does not get any louder with rpm actually can't hear it if you bump the trottle up sounds like it goes away truck idles around 550ish

 

Im interested in finding out whats going on. Nothing drives me crazier than a noise that you can't track down. Post that video when you get a chance!!

 

well crap i started recording to find out the camera was dead, filmed 20 seconds and died. 2nd put that clip on the computer and was dam near 100mb. gotta get some juice and and try again on 720p lol

 

 

Anyinput?