Loud engine knock

hello guys! New to the site, but need answers. Own a 2012 TRD Sport 6 speed manual. As of late been hearing a loud rattling (almost like a bunch of rocks are loose) on the front passenger side engine compartment. Between the fan and first spark plug.

I have changed all the spark plugs and still no fix. The noise is extremely loud in 1st and 2nd gear, but dies down when I accelerate. I have read threads about oil pump, but don't know for sure if that's it. Only 54k on it and I just can't figure it out. HELP!!!

 

Are you absolutely certain about the location where the noise is coming from? It sounds like you have an exhaust heat shield that has come loose/ is rusting off. While poking around, check the tightness of your "skid plate" bolts. Those things will have you crawling all over under the truck with a wrench if they are loose even the slightest bit.

 

Make sure the manifold bolts are tight
Also might want to try to see if the sound happens with the truck sitting still at idle. if so, use a tube or something similar like a stethoscope to pinpoint the origin of the noise. Sounds like an exhaust noise, like a loose heat shield on the exhaust pipe. That type of sound can transmit, and sound like it's coming from somewhere that it's not!

 

Already checked those things and everything is on tight. I pinpointed it to that front area on the engine thinking I had a bad spark plug, so I ended up changing all six thinking that was the issue. However, the noise is still there and loud as ever. It's like this huge rattling sound that's coming within the engine compartment. Can hear it inside the cab with windows up and people can hear the noise when I pull up along side them.

 

Idea. Remove the serpentine belt, and run the engine briefly to see if the noise is still there. If it is, then it might be internal. If not, it's an accessory driven by the belt.

 

Thanks for the input guys. I'm dropping it off at the Toyota Seevice Center tomorrow to see if they can diagnose the problem. I know theirs a noise, so if they tell me it's normal I call bullshit. Hopefully they have some sort of answer...