Rattle from front of motor

[350-91RS]

I have a 350 in my '91 RS and it has a rattle from the front of the motor? The service dept. at the GM dealer says its the belt tensioner, another says its the water pump or in the valvetrain somewhere. I have no loss of power. Any ideas?

[LL6]

when does it rattle? Idle, cruise, etc?

[WS6 VERT]

You can eliminate all your belt driven accessories like the tensioner and water pump simply by removing the belt and running it. If the noise is gone, more than likely its something driven by the belt. If the noise is still present, then its probably something w/ the motor.

Whats the mileage of this motor? Is it a crate engine, used engine, etc...?

[SportCoupe]

Originally posted by DenaliTech:
You can eliminate all your belt driven accessories like the tensioner and water pump simply by removing the belt and running it. If the noise is gone, more than likely its something driven by the belt. If the noise is still present, then its probably something w/ the motor.

Whats the mileage of this motor? Is it a crate engine, used engine, etc...?Just want to add something when running without a serpentine belt. Don't run for long as the water pump is NOT turning and it will QUICKLY heat up.
I mean a minunte is OK but not 5, understand?

[RobP]

What John said! :D
Timing chain slap?

[350-91RS]

I,m leaning more towards the timing chain myself. I,ll run it without the belts tomorrow and see what I have after that. It,s a 350 with the GM hot cam kit with TPI.,headers and some other mods. It only has less than 40k on motor after swap from 305 tbi. Thanks for the info guys.

[WS6 VERT]

I can't say that I have ever heard a timing chain slap on these cars. Usually the cars you hear that on have a tensioner, and the tensioner breaks and the chain beats on the tensioner. Our cars don't have that, and if its loose enough to slap around, you run the risk of jumping time...

[RobP]

I didn't know it was a newer TPI motor. I'm used to old 327's or 307s with the timing chain stretched to the max, but not on our cars. I retract my diagnosis! smile.gif

[WS6 VERT]

Chain stretched, or Nylon coating crumpled? I don't know what GM was thinking to make part of teh gear out of plastic... I've replaced many of Olds 307 gears, as well as the 3.0L V6 after it bent the valves :rolleyes: