* Skip to second paragraph for details on the noise *
My other half's nephew left for the Philippines for a vacay, and asked that I look into a noise that has developed recently in his Corolla. This forum has helped me numerous times so I've started to get a little embarrassed to post my next q here, so ( instead of googling for hours ) I've started to solve my problems through trial and error. I've learned a lot during this time, but I'm still prone to error, which - due to the car not being my own - makes me reluctant to take this engine apart and zero in on the source of the noise.
The noise is hard to describe - I would say it sounds like a marble bouncing around inside of the engine block - not a heat shield rattle nor a worn water pump bearing sound, but a deep rapping noise on metal. Also the knocking is brief - no longer than five seconds or so - and intermittent, occurring only immediately after ignition and AFTER acceleration. It seems to be coming from the crankcase area, on the crank pulley side of the motor, but I haven't put the car on stands yet so I can't be sure... I'm sure it's not the water pump ( noise would be constant ), the heat shield and intake, but that's all Google gave me on terms of an answer... Thank you in advance!
Also, if there is a way to upload video, let me know. That would help answer any other questions you all might have.
Update : Finally found the time to get under the hood again. It seems I was totally off in my assumption that it was the belt and the noise is definitely not metal-hitting-metal... I pinned the origin of the sound to coming from either inside or directly underneath the plastic intake manifold. I think there might be a loose tube??? I worked on a gm3800 with the plastic intake and found the source of a blown head gasket to be a narrow coolant tube that ran through the intake and into the head... Similar design? It doesn't run overly hot, so maybe some other plastic piece inside?