Rattling from Front end

[Kocher93]

I got a rattling that sounds like it comes from my motor, but I'm not ruling anything out. I already went under and checked for anything loose and nothing. It happens only when I idle and its only sometimes. If I give it gas or break it will stop. Trucks a 1989 K5 with a 350>700R4>NP241>10 bolts.
Not preignition by the way. It just happened one day and it's been semi consistant any ideas on this?

 

[K5dreamer]

if the rattle is consistant break out the stethescope or broom handle, and start checking around on things for the sound. if it comes and goes with engine load, im leaning towards a pully bearing, or tensioner (if its a serpentine setup, dunno what year those started)

 

[Kocher93]

It's weird its so sparadic and wont happen for more than 2 seconds but it is loud. sounds like a bunch of slinkys under my hood

 

[doonjumper]

Im going to suggest alt bearing. I had one do that like you describe then it just went out and started screaming at me

 

[Kocher93]

Less than 5k on alt. It's weird its so loud to where its just from the front end. Sounds like the heat shield on the stock manifolds are in a class 5 hurricane.

 

[Chaddy]

Torque converter.

 

[Kocher93]

Brand new tranny TC and flywheel. I'm so confused of where its comming from

 

[K5dreamer]

start going through all the major mounting bolts and see whats loose. could be a flex plate/tc bolt, motor mount maybe? it sounds like somethings loose and as the engine vibrates, the loose thing goes into a harmonic and out again, making the noise.

 

[charity case]

i wouldnt rule anything out based on it being new from past experience.