Grumbling noise at low RPM

I've recently noticed a light grumbling noise has developed from underneath the truck. I have about 117k miles on it. It almost sounds like an exhaust leak, but it's not always present. I usually only hear it 1)briefly at startup, and 2)at low RPM's mostly noticeable when I'm backing up. I inspected what I could underneath and around the exhaust pipe and other associated components, but didn't see any holes or apparent weak spots. It definitely sounds like an air noise, not something rattling loose, but of course I could be wrong about it.

Any thoughts?

 

Figured I would circle back to this for an update, in case anyone has this issue. I had my truck at the dealer for an overdue service. I asked them to check it out, but they didn't notice the noise. So, they asked me to come back and point it out to the tech. Once I drove with them, I could easily point it out. It turns out that the intake air box connection to the truck body/firewall had worked its way loose, and that's what was rattling. They pushed it back in, but I don't know how well they secured it, because I think I hear the noise starting again. At least now I know what it is, and can try to make a more permanent fix.

 

Loosen the clamp on the air box and turn the hose clockwise to put tension on the other end and hold it in place when you tighten the clamp.

 

Thanks, I'll give that a shot.

 

Hmmmm I've had a very similar noise as well. I'll give it a shot!

 

Just in case anyone else is running into this issue, Larzzzz’s fix worked like a charm for me. As soon as I felt the intake air box, I could tell it was probably the source of the rattle/grumble. Larzzz’s fix puts just enough pressure on that connection to prevent any further rattling. Thanks a bunch man!!

for reference I’m in an ‘06 access cab 4x4 with 118k miles.

 

Going to check this out on mine ,been chasing that noise & gets expensive going into shops & paying for tech's who can't here the noise (Hell my wife can hear it)!

 

My '07 has had the "grrr" sound forever it seems and my air box intake wasn't loose, BUT it was still the source of the sound. Certain low RPM it was vibrating against the truck body/firewall. I put a couple washers under each connection on the air intake and Wa Lah, no more Grrrr sound.

 

Mmmmmmmmm? something to check out but I think my air box is different ? Thanks PS: just noticed you have a o7 & a 2014 ..ok Just ran to the store & back a few miles & louder than ever idles faster in park @ 900 RPM by the time I got my tools to take the engine cover off it had got much quieter . Also curious about Belt & Idler & tensioner & Pulleys ? Every shop I go to says they can't hear anything but I don't think they really pay attention ,heck my wife can hear it . Tough to find a Tacoma shop around Spokane & I know there has to be one of those everyone goes to guy's.