3rd Gen Poll: Rear End Noise howling when feathering throttle

Taco is getting a new diff today due to the howling noise. Hope I have no more issues but only time will tell.

 

In all seriousness, could this diff bolt recall potentially be a source of the howl? I know that so far, the TRD OR (which is most definitely howling too) is not recalled, but hear me out.

Everyone so far has been speculating that it's the ring & pinion that are howling. Could it maybe potentially be that the side gears / spider gears are getting loaded because the diff bolts are soft & stretching, allowing the axles to apply a load?

My understanding is that side gear noise because of axle misalignment WOULD go away under load & would only be during "feathering" , plus this would explain why replaced diffs started to howl again, if the stretched studs were not replaced.

Is it really that easy? Have we just been looking at the wrong gears this whole time?? I'm a noob at diff setup / drivetrain diagnosis though, anyone care to comment?

 

It is not that easy. The recall is for under-torqued fastners which can in some cases cause a leak of fluid resulting in a dry diff. The pinion howl is a completely different issue but both point toward lapses in QC.

 

In that email thread that was posted yesterday or it might have been on the Recall itself, it said something along the lines of more future resolutions coming, maybe that will address the howling.

 

The recall states to check the fasteners, but the speculation (based on snapping studs that a number of members have experienced) is that it is not because of under-torque (read what smitty posted again, note that it does not say under-torqued anywhere, and when a leak is found, all fasteners are replaced.) Basically the bolts are thought to be stretching because of improper heat treat, not under-tightened from the factory.

Hence why I'm saying maybe it's NOT a different issue.

 

Almost right: the vehicles with no leak just get re-torqued. If leaking the gasket gets replaced and in that case one gets new fasteners.

At any rate - very unlikely this condition would result in pinion howl.

 

Correct

 

I think there are 2 issues here. First off, your logic is good, and the leak could lead to all the other mess. However, I know of 2 Tacomas with howls; that never leaked and have the right fluid levels of Toyota lube.

 

Are there any videos showing this howl? Haven't kept up with this thread...

I'm at 24300km on my TRD Sport and started hearing something recently. Might be a howl, might not be. Seems like it's coming from the front, though. And it's more audible with the windows rolled up than rolled down... go figure. I did hear it last night at around 50mph with coasting or feathering of the throttle, so that much lined up with the diff howl.

 

My thoughts are the re-torque is the Toyota cost effective method of saying "F*** it, close enough" - as in, if it's not a problem now, don't worry about it because the studs are "probably" fine.
Let's not forget that replacing every last set of diff studs and gaskets gets expensive fast, because it requires removal of the 3rd member.

also AAAAAAAA I DIDN'T SAY PINION HOWL, why does everyone keep going back to pinion howl?!?!

That's the point I've been trying to make!! I've been told that side gear loading does sometimes cause a howl on decel...

Hmmm, one would think that stretched bolts would inevitably lead to gasket failure... I dunno though, I have no idea how sensitive the side gears and axles are to depth vs how much "slop" can a gasket take up.
If a gasket can take up 1mm of play without leaking but axles misaligned by 0.5mm causes noise, it might still be the cause. However, if the tolerances are the opposite then that theory is completely out the window.

 

Mine does it. Along with clanking slowly over speed bumps, leaking rear diff (not on vin list for recall), terrible brakes. What fun this truck has been.

 

I posted a video I don't know how many pages back of both my old howling differential and the new one they gave me howling. Might try searching on youtube for 2016 tacoma differential noise. I'll try to find them later and repost them.

 

Thanks. Found your videos in these posts:

https://www.tacomaworld.com/threads...thering-throttle.442341/page-36#post-13082394
https://www.tacomaworld.com/threads...thering-throttle.442341/page-46#post-13174957

Definitely not the sound I heard in mine. I guess that's good news? :/

 

485 Hz. Were you going about 58 mph?

 

There is a whistle sound that comes from the front and is the Lower A Arms, there is a TSB to plug the holes, may possibly be what you are hearing.

 

Mine sounds exactly like the video. I have a MT, when I put into neutral howl goes away. Back into gear and the howl is heard again. Also, inspected this morning, noticed I have rear diff leakage. My VIN is not on the list, but it's my understanding the list hasn't been completely updated?

 

Thanks, but no. I had the LCA whistle before and have since had the TSB done.

 

Yep, right on the money. 58-59 mph.

 

I can't believe there are so many people complaning about this issue (including me) and Toyota has not been able to fix it.

 

I may have heard one time briefly but it was only when I had a full load of passengers. Have not heard since.