2007 Tacoma - Roaring/humming noise in Reverse when Cold only

I have an issue with my 2007 Tacoma PreRunner 2WD Double cab that I can't find any help to figure out. Any thoughts or anyone had a similar issue?

1 - Issue happens ONLY WHEN COLD, and ONLY IN REVERSE in the mornings when I back out of the garage.

2 - Sound seems to be coming from the passenger side front near the front wheel or that side of the engine bay or front passenger side fire wall area.

3 - This is NOT a clicking, rattling, screeching, grinding type noise. It sounds like a roar/hum from plastic vibrating against metal or maybe an exhaust rubbing against metal or plastic. It is a loud hum/roar and it only does it in reverse when cold. Once the engine is warm, it will no longer do it.

4 - To complicate the diagnosis, while I am backing out of the garage in the morning with the hum/roar happening, if I stop and put the tranny in Park or Neutral then back to Reverse the noise will not happen anymore.

5 - I had the transmission serviced a few months ago, it shifts smooth as silk and there are no apparent issues with the truck in any way.

6 - I had the truck put on a lift and the heat shields were checked and everything inspected underneath to make sure there was nothing rubbing.

Any suggestions would be greatly appreciated!

 

My guess is it’s coming from the intake plumbing where it is bolted to the fender. Loosen it up and move it a little bit.

 

^ this

 

Are we being greatly appreciated yet?

@mlinn1967

 

I have looked at this already because I had heard on the internet that was the source of some noises but mine appears to have plenty of foam around the edges and is extremely tight going into the fender well, so I didn't think that would be it. I will take another look at it however to rule it out and maybe just pull it out of the fender well all together and see if it does it that way. Thanks again for the suggestions.

 

When you do that and find out how cheap the foam is and how it's placed and how close the air horn is where it goes thru the fender, you'll see what they mean.

 

Assuming this is what is causing the issue, and it very likely is, what is the best way to fix this problem? I think I read somewhere that there was a TSB out on this at some point? If so would the Toyota dealership have to fix this even though the vehicle is 10 years old?

 

Some have had luck adding some weather stripping to the hole and intake tube. I replaced my stock intake for a TRD and the noise was gone

 

The first time I found out what was making the noise I used blue painters tape and some dense foam to pad out the air horn, worked for about three years now it's back, this time I'm going to put cut vacuum hose around the hole (next idea) to see if that works.

 

I looked at mine and everything was lined up and tight. I found the noise by opening the hood on a cold morning and getting my former son in law/toyota mechanic to listen when I put it in reverse. He put his hand on the piece that goes through the fender and the noise stopped. I loosened it up and moved it a little bit and retightened it. It’s been years now and it hasn’t come back. Even after having the frame replaced last year. Just lucky I guess.

 

Update: Replaced the factory intake with the Spectre cold air intake system, and the noise disappeared! It was for sure the air horn going into the fender causing the horrendous noise. Thanks for everyone's input!