Intermittent noise from under vehicle while idling at stop

[rpm215]

2005 Sport V6 w/ about 185K

Scenario: I'm at a stoplight, idling, foot on brake. I'm in drive. Everything's normal

Maybe 10-15 seconds later, I'll suddenly hear a "bang bang bang bang bang"....about 5 bangs per second...until I start going again. I can hear it in the cabin...it's louder if I open the passenger side window.

It sounds like it's coming from under the vehicle, perhaps the rear passenger side. But I'm really not sure. Also, I feel no vibration. Also, no dash warning lights, codes, etc. I don't notice the tach responding while it's happening

I noticed it about a week ago, but it's been intermittent. As such, I've not been able to catch it to do some tests...like what happens if I drop the transmission into park, etc. And I've not been able to get out and look under the vehicle while it's going on.

As another sound reference, the first time I heard it I saw a truck go by around the same time and assumed it was the truck's jake brake, because that's what it sounds a bit like (at least to me)

I was assuming loose fitting somewhere in the exhaust system, but the fact that it's intermittent and that I don't hear it going over bumps, etc, has me a little stumped.

Any thoughts?
thanks!

 

[Billynath1988]

Because your idleing, and the speed at which its the bang appears to happening also the side you think you hear it on.. Id say its something with the exhaust vibrating on something.. especially with no feeling in the driving or check engine lights or movement being involved. But its a wild guess with the info provided at this point.. Grab the tail pipe.. while its cool of course.. and try shaking it.

 

[loarmistead]

Curious if it correlates with the AC clutch. At idle, perhaps the AC kicking on ever so slightly changes the vibration of the motor, which creates a frequency on the tail pipe that is hitting something.

If you're sitting still at a stop light there isn't much moving in the back that could be creating a noise like that other than the exhaust pipe.

 

[Elan750]

check the heat shields. They are flimsy and often break, often rattling against something when the rpms get low enough (intermittently at idle)

 

[crossfire190]

Definitely check your heat shields. Fix by removing existing nuts and putting in a large washer/spacer and replace nuts.

 

[ShutterTramping]

2005 Sport V6 w/ about 185K

Scenario: I'm at a stoplight, idling, foot on brake. I'm in drive. Everything's normal

Maybe 10-15 seconds later, I'll suddenly hear a "bang bang bang bang bang"....about 5 bangs per second...until I start going again. I can hear it in the cabin...it's louder if I open the passenger side window.

It sounds like it's coming from under the vehicle, perhaps the rear passenger side. But I'm really not sure. Also, I feel no vibration. Also, no dash warning lights, codes, etc. I don't notice the tach responding while it's happening

I noticed it about a week ago, but it's been intermittent. As such, I've not been able to catch it to do some tests...like what happens if I drop the transmission into park, etc. And I've not been able to get out and look under the vehicle while it's going on.

As another sound reference, the first time I heard it I saw a truck go by around the same time and assumed it was the truck's jake brake, because that's what it sounds a bit like (at least to me)

I was assuming loose fitting somewhere in the exhaust system, but the fact that it's intermittent and that I don't hear it going over bumps, etc, has me a little stumped.

Any thoughts?
thanks!

I had the exact same issue a few years ago and it was indeed the heat shield. I removed it amd it remains off today.

Sent from my SM-G900V using Tapatalk

 

[Montego Murph]

Give this thread a read -- it sounds a lot like what I dealt with a few months ago.

http://www.toyota-4runner.org/4th-g...-rpm-odd-rubbing-noise-trying-figure-out.html

 

[rpm215]

Heat shield above the muffler

Thanks all the for the replies...it was nice enough and cool enough today to take a look at the vehicle, and the problem was apparent immediately - the heat shield directly above the muffler had come off one its supports

Luckily it's the support toward the front and closest to the wheel, so I'm going to see if I can loosen the nut and put a washer on it, but there's not much clearance. and I imagine it will be a matter of time before the other side comes off.

Thanks again.

 

[rpm215]

Give this thread a read -- it sounds a lot like what I dealt with a few months ago.

http://www.toyota-4runner.org/4th-g...-rpm-odd-rubbing-noise-trying-figure-out.html

This thread even had the spec for the hardware. Thanks!