I've noticed recently I have a metal on metal rattle underneath my truck. It gets worse when I'm halfway on the throttle. If I throttle harder it goes away, or if I let off the throttle it goes away. Maybe a heat shield?? The heat sheilds didn't feel loose to me when I try to move them by hand.

Have any of you guys ever had this problem? It's gotten to the place now that it is irritating the life out of me.

check that your spare is cranked up all the way... some people have complained of this only to find their spare was drooping.

No, this is like a "tin metal against tin metal rattle" type of sound. I have also noticed that when the truck is cold it's not there, but as the truck warms up to driving temperature (like when the exhaust piping and manifolds are hot) is when it is really bad.

If my truck is in "park" or "neutral" and I rev the engine there is NO rattling. I have to actually be in "drive" for it to happen.

I wonder what it would cost to just have all the heat shields replaced.

You may have what they call "pinging" Try a higher octane fuel and see if the noise changes of goes away.

have you checked your motor mounts and exhaust hangers??

i think ihave the same noise, its the heat shield on the catalytic converter behind the front passenger wheel. my mounts are broken there and the heat shield is somehow dented in (must have run over a pebble at sometime in the 4runners life) and it only makes the noise in drive. i would check your exhaust hangers and heatshields. good luck with you search

LOL...it's not pinging.

Checked the motor mounts and exhaust hangers.

I really think it's going to be the catalytic converter shield.

well i was quoted upwards of 1000 for a new cat from toyota, dont know if i was wearing lipstick on that day or not, but ive decided that if i ever take care of it im just gonna reshape the cat to look more like a straight pipe....

I would think you could just replace the heat shield...right? You shouldn't have to replace the entire cat. I wonder if you can just remove the shield altogether?

Ok, I have been looking underneath the truck this morning, determined to find where that damn metallic buzzy rattle is coming from. I'm pretty sure I found it.

The catalytic converter heatshield has a top and bottom, held together by four nuts/bolts (one at each corner). Well, the bottom part of the heatsheild at the rear right nut/bolt has about a 3/4cm crack. You can vibrate it by hand if you try to move it up and down really fast. So, I just drilled a new hole and secured that section with a new nut/bolt. There is no play in it now. I'm pretty sure this is where it was coming from. I used threadtite to secure the nut/bolt, so I'm letting it sure for about an hour before I go driving it.

So, I'll see in a little while if I fixed the problem or not.

Thanks for your help guys.

Chris

Is it ok to quote yourself?? Anyway...I FIXED IT! No more bussy rattle!! My 4runner has been such a pleasure to drive today...and NOBODY has stared at me funny when I drive by them. Guess nobody notices me now that all that noise is gone!

Again, thanks for the responses and help.

Chris