Unexplainable, Undiagnoseable, Unlocateable Flapping/Gringing Sound

Ok, I have been dealing with this sound since I first heard it about six months ago. I have a 2016 2WD V6 Auto. I want to be clear- although I do have a lift on my truck now, it started before I lifted my truck but I continue to hear it now. I have taken it to Toyota but they have been "unable to reproduce the sound." Those people are totally retarded; I told them it would be unreproduceable because it only happens once every three or four weeks or so, and literally never repeats itself in the same day or even the same moment. I just wanted them to check and see if everything looked normal underneath my vehicle. I have struggled to locate the source of this sound but I am desperate because it doesn't sound good and I'm afraid it's causing some damage.

So here's the deal- when I'm driving my vehicle coming out of a not too steep driveway or sometimes even a drainage grate in a parking lot, I will hear a loud grinding sort of flapping sound. Not only do I hear it but the worst part is I feel it. I can feel it underneath like where my gas pedal and brake pedal are. If my foot is on the gas pedal I can feel the vibration through there. If it's on the brake pedal I can feel it through there. I'm going to attempt to explain the sound the best I can, so bear with me. If you were to take a piece of thin sheet metal and jam it into the blades of a circulating fan while it was running it would sound very similar to what I'm hearing. The difference is it's very metallic. Or if you can imagine the sound your vehicle makes when you deviate from your lane and you run over the little white lane dividers - that BBRRUUPP, BBRRUUPP, BBRRUUPP sound - it sounds exactly like that but just more metallic. Which is what worries me the most. I have no doubt that whatever is going on underneath my vehicle is not normal and it's coming from that area directly underneath my feet, or at least it seems like it is because I literally feel it through my feet on the floor board. I've crawled underneath there and spent hours trying to find out what could be making this sound and I have found nothing. Some important notes to keep in mind-

• It has been making this sound even before I installed my lift kit.
• It has never, and I repeat never, has ever made this sound going over huge speed bumps, coming out of steep driveways with a steep dip or change in grade from the drive to the roadway.
• It has never made this sound running down the road at any speed over smooth roadway, potholes, dips, bumps or uneven roadway of any kind.
• It has only ever done it on the slightest of dips at very slow speed, and it has done it both running straight and went slightly turning left or right.
• In the last six or seven months it has done it about once a month on average, and then just goes away only to repeat itself a few weeks later.
• I can turn around once it has made the sound, go back over the same drainage dip or driveway dip that has just caused the grinding flapping noise, and it will not duplicate the sound no matter how many times I repeat this exercise.

I AM LITERALLY AT MY BOILING POINT TRYING TO FIGURE THIS OUT! There doesn't seem to be any thing mechanical in the area under the floorboard directly in front of the cab that could be causing this metallic grinding flapping sound, a sound, like I said, that sounds similar to a thin piece of sheet metal been jammed into the blades of the fan. Which by the way I have checked just to see if anything was jamming up in my fan blades. But like I said it's coming from under the floorboard in the area right around the end of the cab. Anyone have any constructive useful thoughts or ideas as to what this could be? I have no doubt whatever it is is causing some damage I just wish I could figure out where it's coming from...

Sorry for the really long length of this post but I could use some help.

 

Driver's side front diff needle bearing?

Did you change this out to the ECGS bushing yet?

Whichever the case, if you haven't, you should, you have a big ass lift.

Also, with that big of a lift, I would regularly check all u joints, cv axles, etc

 

I was driving in some wild snow and slush slop and collected a buttload of frosty sloppy slushy mush on one of the heat shields underneath. It made a metallic kind of dragging sound.

The heat shield got folded over and started rubbing on the drive shaft. One of the plugs or push pins that held the heat shield onto the side of the gas tank was missing. It was really easy to bend outta the way, hasn't made any noise since.

 

should have had the dealer resolve this prior to lift.

 

His truck is a 2wd... hard to do that in his case.

 

Now I see that. With that big of a lift I'd check all u joints and cv axles.

 

Bent dust shield behind a front brake rotor?

 

Yea check heat shields, rotor shields, skid plate or tire rub. Somethings bent and making contact somehwere. I would try to find a spot where it makes the grinding noise, go real slow and stop at the moment you hear it and then go check.. or post detailed pics of your drivers side wheelwell maybe something someone can pick out..

 

Take your truck to a gravel path, slick road, wherever... get up some speed an press the brake enough to engage the abs. To me it sounds like a normal abs engagement. That’s the sound, and feel of a normal abs engagement. I’m just throwing this out there, might not be your issue, but I used to be a ford dealer technician, and you’d be very surprised at the number of people who haven’t ever experienced a normal abs engagement, and thought something terrible was wrong when they actually had it happen. Good luck

 

Thanks for the input but like I said in the beginning of the post, mine is a 2WD and is had done it since before it was lifted. First time at around 6K miles, only 17K on it now...

 

Checked but it clear...

 

Tried... twice. Hard to resolve when they can't replicate the issue.

 

Thanks. Removed those before lift install...

 

Rotor shields removed but I have zero clearance issues at full lock and full "stuff", since I have a lot of lift and conservatively sized wheels and tires. No rubbing marks on anything anywhere. Like I said, more metallic sounding.

All of these replies highlight the difficulty I'm having figuring it out. All great answers but so far no luck.

 

That's the one thing I haven't considered.... it does always happen when breaking but at VERY LOW SPEED, and never at full lock, in fact usually when driving straight. That's the crazy part

 

I know it’s frustrating.. I’ve had several trips to the dealership with “could not duplicate”. Problem may be in the rear of the truck. Sound and vibration may be resonating forward, and your feeling it in the brake/ gas pedal..

 

Try making the abs actually work. That’s very possible, even at low speeds

 

I'm voting on abs engagement. It happens to me occasionally in a turn over a small incline that then goes back down in an entrance to a parking lot. It sounds and feels exactly as you describe it.

 

Last winter I had the abs activate on a regular basis....normal pedal vibe, but never a metallic sound?...sounds like definitely metal to metal contact.

 

I wish I could describe the sound a little better. If you took small box fan and replaced the plastic blade with a metal One, and then took a sheet metal strip about 2" x 6" long and you jammed it into the blades that's as close as I can describe the issue.

Many years ago I had a Chevy Silverado, that every time I made a turn the blade on the fan at the radiator would rub on the plastic fan shroud. Did it from day one, took it back easy warranty fix. This sounds a lot like that except for the Damn metallic sounding part, and of course the fact that it's under the floor more towards the front of the cab. I really appreciate all The input from everybody. This has been the best sorry for everything Tacoma related and I appreciate everyone's help. Please, keep the suggestions coming!