I have a 2000 L, Stock except for the cat back exhaust.

When the truck is warmed up and I'm sitting at a light I can hear a rattling noise coming from the engine compartment. If you put the truck in park or netral the sound goes away. It only does it when the rpm are below 600-700. As soon as the rpm's go up the sound goes away.

Any idea what's causing this? Should I be concerned?

Thanks for your help.

 

It's heard when the engine is under a slight(at idle) load and not at any other time............

May be a loose s/c belt and/or 'dry' idler pulleys? That's all I can think of now.

Dan

 

Thanks LIGHTNINROD

Ya, it only does it when in drive and stopped. If it's in park and idling it sounds just fine.

If my Idler pulleys are 'dry' what do I do to fix them.

Thanks