Mystery Noise...?

[FRANKENTRUCK]

My truck (engine ?) has recently begun making a strange noise. When you start it there is nothing out of the ordinary. But if you rev the engine or go 40 MPH or greater there is a distinct metallic tinging sound. I am not sure if it is the actual engine, but I guess it has to be. Imaging cutting up aluminum soda cans, putting them in a small box, then turning the box over and over slowly. That is the type sound I hear. It does not do this at low speeds or at idle, there has to be reving or 40 MPH plus speed. There is no abnormal smoke, very minimal oil use, and the oil pressure is PERFECT. This is not a loud noise, it is just ANNOYING and abnormal for the truck. Any ideas what it could be?

 

[89Suburban]

Pulley accessory?

 

[FRANKENTRUCK]

Could the pulley assembly possibly make such a noise? I have never heard this type of noise before but then I have never had a pulley assembly go bad on me.

 

[crazy4offroad]

Timing chain.

 

[FRANKENTRUCK]

Update

I spoke with the mechanic who installed the motor and transmission last year. He thinks that the torque converter is making the noise due to the fact that the noise is not constant i.e. it only occurs under certain circumstances.

 

[chengny]

Easy enough to check. Drop the flex plate cover and inspect the inside for metal dust/chips. If you find any evidence of metal-to-metal contact, determine where it's coming from.

With the cover still off, jack the T/C over using a prybar on the ring gear. As it is rotated, look for shiny spots that would indicate interference with a stationary object. Look closely at the flexplate-to-T/C bolting.

Also, while the cover is off, try to look up into the bellhousing of the transmission for evidence of something making contact with the T/C.

Unbolt the flexplate from the T/C. Check the flexplate/crankshaft bolting for tightness.

Next, using both hands (and always pushing in towards the transmission), wiggle the torque converter back/forth and up/down. There shouldn't be any noticeable play.