[2006MDSienna]

I'm trying to track down a drone sound coming from the rear of our 2006 XLE AWD. I thought it might be the wheel bearings but I jacked the back up to replace the diff fluid and there was no play at all in either wheel and they seemed to rotate relatively freely. The only sound from either seemed to be from the pads scraping the rotors.

The loud drone from the rear is pronounced when I get over 1500 rpms and 40-50 mph's and when I'm throttling the gas. When I take the foot off the gas and coast, the drone sound is immediately reduced significantly or goes away as soon as I take my foot off the gas pedal. If the rear bearings were bad, wouldn't they make the same sound whether I'm throttling the gas or not?

 

[Job2480]

Based on my experience, my bet is it is coming from your exhaust. It is a harmonic drone. You just hear it somewhere other than where it is coming from.

My 2008 FWD (bought used last year) has a drone sound around 2400 rpm when under a load. Any gear. Once the transmission shifts, or I let off the accelerator - so that the rpm changes, the drone sound immediately stops. I had it in my local Toyota dealer. They ultimately said it was a rear wheel bearing. Road trip with both the service manager and a mechanic where I reproduced the sound. Mechanic laid in the floor in the back listening around while I drove. Replaced the hub assembly. Made ZERO difference. I spent several hours googling. Apparently drone sounds are common in Sienna, though at different rpm. I read one thread where someone had similar problem and had a non-dealership mechanic that modified a heat shield somewhere on the exhaust pipe and the drone went away. Seems like they bent it or added something like J-B Weld. Changed the harmonic. My exhaust has 2 harmonic dampers on it welded directly to the pipe. I just gave up. It is a constant reminder of my dissatisfaction with Toyota on this issue. If this is a known issue or common issue, why doesn't Toyota have some kind of TSB or something? I asked the service manager to run it up the flag pole. Never got a response. Either it was never escalated, or Toyota doesn't want to acknowledge the issue or fool with me.

I talked to my normal non-dealer mechanic about it. He said drone sounds are common these days across all brands. He mentioned one brand of pickup truck that on all but the base model included an option to sound cancel drone sounds in the exhaust. Don't remember the year or model. Customer bought the base model without it. Has the drone sound bad under certain conditions. My mechanic does lemon law/defect investigations and reviewed the vehicle. His determination was that the vehicle was operating as designed given that the customer bought a model without the noise cancelling feature. In thinking about that later, I seriously doubt if anyone at the dealership advised the customer they were buying without this feature.

 

[BillG]

A few things...

Anything scraping the rotors is generally a bad thing and you probably want to address that.

Next, it seems the wheel bearings can be bad without any play. I've read many stories here of people trying to figure out one of these types of issues and they eliminate wheel bearings first, by checking for play, do a bunch of other tests/replacement and then come back and change the bearings anyway and the problem resolves.

With FWD, you only have 2 things which can make noise originating from the rear... Wheel bearings and brakes. With AWD, you also have the diff, axle shafts and the driveshaft. Since you're currently under the position that the bearings are good, I would look at u-joints and, if there is one, a carrier bearing, although, I don't know that the Sienna actually has a carrier bearing. There's also the possibility that the noise is radiating from another thing (i.e. engine, transmission, etc.) and transmitting seemingly from the rear drive assembly. The reason you hear it under load and it stops (or reduces) when you coast is likely a function of torsional stress. When you press the gas, you're "pushing" the car forward. When you coast, inertia is taking you along and the drive assembly is just "pulled" along for the ride. That's the reason I would guess the issue is something on the driveshaft. Although, after you eliminate all other possible sources, you might come back to the wheel bearings and just change them out, just because, and find your problem is fixed.

Finally, as @Job2480 said, it could just be harmonic noise coming from your exhaust and you could entirely ignore it. However, without actually hearing it in person, I couldn't make that determination. I will also add that you should try and make some controlled observations and determine if it's JUST a sound or something like a sound and vibration. If it's a vibration too, you can throw in things like an alignment issue (rear is a non-adjustable beam axle), a bent/warped rim, unbalanced tires, etc.

 

[jac]

I'm trying to track down a drone sound coming from the rear of our 2006 XLE AWD. I thought it might be the wheel bearings but I jacked the back up to replace the diff fluid and there was no play at all in either wheel and they seemed to rotate relatively freely. The only sound from either seemed to be from the pads scraping the rotors.

The loud drone from the rear is pronounced when I get over 1500 rpms and 40-50 mph's and when I'm throttling the gas. When I take the foot off the gas and coast, the drone sound is immediately reduced significantly or goes away as soon as I take my foot off the gas pedal. If the rear bearings were bad, wouldn't they make the same sound whether I'm throttling the gas or not?

Bearings make more noise when loaded like when you are turning left or right on the highway or when accelerating as you described. If you notice the sound gets louder turning one way, it is the opposite (loaded side)bearing. Just something to check. Mine was quite and tight on the rack, but noisy when turning on the highway. Like @BillG said there is a lot going on back there on an AWD besides wheel bearings.

 

[jseyfert3]

I'm trying to track down a drone sound coming from the rear of our 2006 XLE AWD. I thought it might be the wheel bearings but I jacked the back up to replace the diff fluid and there was no play at all in either wheel and they seemed to rotate relatively freely. The only sound from either seemed to be from the pads scraping the rotors.

The loud drone from the rear is pronounced when I get over 1500 rpms and 40-50 mph's and when I'm throttling the gas. When I take the foot off the gas and coast, the drone sound is immediately reduced significantly or goes away as soon as I take my foot off the gas pedal. If the rear bearings were bad, wouldn't they make the same sound whether I'm throttling the gas or not?

Yeah I think so. And more noise when going around corners and side loaded.

Also you can't apparently always tell by play and rotation if they are wheel bearings. I had a friend with a Subaru (AWD), who asked about this noise in their car. We went for a drive and it was continuous. I shifted into neutral while driving and the sound stayed the same. So not engine or exhaust related. Seemed like a wheel bearing but I had no curves I could drive fast around to check for changes in noise with side loading.Got back, jacked up, wheels turned smoothly with no play. I didn't have time to check further, but they took it to the dealer and it was a wheel bearing. So long story short play and free rotation doesn't mean the wheel bearing is good.

But driving in a straight light and taking foot off the gas pedal, yeah, I can't see that being the wheel bearing. Something else in the drivetrain or the exhaust for sure.

 

[2006MDSienna]

I'll see what happens when going on turns and curves, and if the noise changes. Might be a bit of a challenge as I'll have to keep throttling the gas, since the droning cuts out as soon as I take the foot off the pedal. I flushed the transfer case and rear diff to see what was going on. No metal chunks - just a tiny bit of dusting around the magnets and not much at that. Put in new oil but same drone. Its due for an oil change and tire rotation, I'll take a closer look at the exhaust and driveshaft when I have it up on the jacks.

 

[2006MDSienna]

Welp, I put it up on jacks to replace engine oil and rotate tires. Long story short - when I finished and lowered it I had a new problem-it now clunks when I shift to reverse. That has never happened before, so I'm thinking the movement from jacking it up from the rear diff may have further compromised the driveshaft or u-joints, which may have been the problem all along.

When I replaced the diff oil the week before, I lifted up from the same spot-which is the jack point on awd's according to the service manual-to put it on jack stands and didnt have any problems shifting in reverse when I was done. Ive always jacked from the diff w/out problems.

Im guessing the drone was from failing ujoints, and jacking up from the diff made it slightly worse.

When I inspected, I couldnt detect any play in the driveshaft, and it seemed to rotate freely, but the rear ujoint looks pretty worn/rusty. Other than that nothing else looked suspicious along the exhaust. The rear axle beam bushings will have to be replaced at some point, but with the clunk on reverse as a new symptom in response to jacking up from the diff Im thinking its driveshaft ujoints. I'll post pics of the rear ujoint later.

 

[Roader]

I don't have an AWD Sienna and have no personal experience with the rear drivetrain but I've hear horror stories about bound up u-joints destroying rear differentials plus there's a center driveshaft support bearing that can go bad. RockAuto sells all of them pretty cheap. It might be worth it to put new u-joints on the driveshaft just as preventive maintenance.

 

[BillG]

Personally, if it was me, I'd be doing U-joints, just because. That said, a thunk in reverse can also be a result of broken springs, so I'd probably inspect those too, just in case. I'd probably also check your rear shocks to make sure they aren't failed too. A broken spring could also put a weird twisting load on the rear end, causing your original groan.

 

[2006MDSienna]

Personally, if it was me, I'd be doing U-joints, just because. That said, a thunk in reverse can also be a result of broken springs, so I'd probably inspect those too, just in case. I'd probably also check your rear shocks to make sure they aren't failed too. A broken spring could also put a weird twisting load on the rear end, causing your original groan.

Yeah, I just ordered u-joints from Rock Auto. The springs looked ok, the rear shocks definitely need replacing. I know the u-joints are staked but a local machine shop is willing to pull them out and install the new ones for $150, so all I have to do is drop the driveshaft. I'd do it myself, but I'm running out of time and have a long road trip coming up so I don't have much margin for messing around. I called around and not surprisingly most shops said I'd need a new driveshaft. One even specializes in driveshafts but never heard of staked u-joints. I live in Central MD and it's slim pickings.

 

[Roader]

Good pictures: DIY: AWD Driveshaft Rebuild

 

[2006MDSienna]

Good pictures: DIY: AWD Driveshaft Rebuild

Thanks. I may try to tackle the U-joints this weekend on my own. The carrier bearings surprisingly seem ok - the bushings don't have any cracks and there was no play when I pushed and pulled from side to side. I would have to yank hard with both hands to get any movement beyond a few centimeters at either of the two carrier bearings. Since I have the U-joints already on order, I may just start with replacing those. From the looks of it, once the new u-joints are in place they don't need to be removed if the carrier bearings have to be replaced later. Small favors... I wonder if anyone has tried to replace the carrier bearings without dropping the driveshaft.

 

[datsa noydb]

Welp, I put it up on jacks to replace engine oil and rotate tires. Long story short - when I finished and lowered it I had a new problem-it now clunks when I shift to reverse. That has never happened before, so I'm thinking the movement from jacking it up from the rear diff may have further compromised the driveshaft or u-joints, which may have been the problem all along.

My '05 AWD did not drone, but it did have a CLUNK when shifting to reverse. Eventually, it also happened just by lifting on the throttle. Tracked that down to the splined joint where the axles fit into the differential. Never did anything to fix the issue, just remained aware of the situation and was more gentle with my transitions on/off throttle.

.

 

[2006MDSienna]

My '05 AWD did not drone, but it did have a CLUNK when shifting to reverse. Eventually, it also happened just by lifting on the throttle. Tracked that down to the splined joint where the axles fit into the differential. Never did anything to fix the issue, just remained aware of the situation and was more gentle with my transitions on/off throttle.

.

Thanks - that's interesting. Maybe jacking up from the diff and having the axles hang there triggered the clunk after all. Seems to have lessened a bit over the last few days, but we'll see.

 

[Johnny5]

I had something similar and it turned out to be a rear wheel bearing. I managed to replace both front bearings before finding the bad one in the rear.
It's a bolt off bolt on procedure. No special tools needed.

 

[2006MDSienna]

Well it turns out the vibration and rear droning noise upon acceleration were the result of worn u-joints. I dropped the driveshaft and saw that the rear u-joint in particular was very rusty and it looked like one of the caps was starting to break up. I tried removing the rear u-joint but the caps were seized up pretty badly. I was running out of time so I took it to the only machine shop in the area willing to take them out and they replaced all three. Popped the driveshaft up and not only is drone gone but the clunk when shifting in reverse went away too. One other thing - the carrier bearings were in surprisingly good shape - rubber bushings were not cracked and no sounds when they were rotated. And that's with 267K miles.

If I had more time I would have done two things - first, I would have grinded down that edge around the lip of the openings where the stakes are punched through. I used my rotary tool (wen) but was hesitant to take too much off. Since the replacement ujoints are recessed too and don't seat against the top edge of the opening, there was no reason to be too concerned, like the guy in this video says

.

Second, that failing I would have just cut two arms of the cross with my grinder or rotary and pulled the ujoint out that way and been done with it. Seems a bunch of folks on other toyota forums with staked U's have done that without issues. Anyway, live and learn.

 

[2006MDSienna]

So the Sienna ran perfectly for a day and a half - the loud drone/vibration went away and no clunking when shifting in reverse. But towards the end of my long road trip - 300 miles - I started getting vibration at the rear at speeds over 50mph. With the old u-joints I was getting a drone and vibration on acceleration and any time foot was on the gas pedal, and both the drone and vibration let up as soon as I took foot off the gas. And that vibration was high frequency - almost constant.

With this new vibration - it's more pulsating and it happens at between 50-80ish whether I'm throttling the gas or not. I don't think its the new u-joints and I checked to see if there was any play in the driveshaft or support bearings, but there isn't any. Still not getting any clunks on reverse or any drone sounds or growling.

Wheel bearings? Is it just a bad coincidence that it comes up just after I replaced the u-joints.

 

[BillG]

It could be as simple as a wheel balance. A lot of people have gone into the exact situation you have now, checked the wheel bearings for noise/play on a lift/jackstands, rotated and balanced tires, replaced the brakes, and even checked the wheels for warps and ruled out every single potential source. As a last-ditch effort, figuring the bearings are old anyway, they replace them and find the problem goes away. But it COULD be any of those things plus your seemingly good carrier could have a slight issue at high speeds. It's probably not a coincidence. It's probably a probably of most-significant-symptom plus the fact that you are now paying extra close attention

If you haven't done it in a while, I'd probably have the tires rotated and balanced. If you want to go systematic, you can rotate the tires front to back. If the vibration goes away or gets worse, you probably have a warped wheel. If you have them balanced and the problem goes away, obviously it was a tire balance issue. If it's been at least 30k miles since the last service, I'd probably also service the differential and inspect for any issues that might be hiding in there. If those things don't fix the issue, I'd probably look at wheel bearings, because they're the next, least expensive fix.

 

[2006MDSienna]

It could be as simple as a wheel balance. A lot of people have gone into the exact situation you have now, checked the wheel bearings for noise/play on a lift/jackstands, rotated and balanced tires, replaced the brakes, and even checked the wheels for warps and ruled out every single potential source. As a last-ditch effort, figuring the bearings are old anyway, they replace them and find the problem goes away. But it COULD be any of those things plus your seemingly good carrier could have a slight issue at high speeds. It's probably not a coincidence. It's probably a probably of most-significant-symptom plus the fact that you are now paying extra close attention

If you haven't done it in a while, I'd probably have the tires rotated and balanced. If you want to go systematic, you can rotate the tires front to back. If the vibration goes away or gets worse, you probably have a warped wheel. If you have them balanced and the problem goes away, obviously it was a tire balance issue. If it's been at least 30k miles since the last service, I'd probably also service the differential and inspect for any issues that might be hiding in there. If those things don't fix the issue, I'd probably look at wheel bearings, because they're the next, least expensive fix.

Thanks. New u-joints got rid of the drones/growling and one kind of vibration only to give way to another kind of more intense vibration less than 5oo miles later - frustrating. I just rotated the tires less than 2 weeks ago and flushed the differential as well. I may have them checked for balancing.

 

[2006MDSienna]

I'm tempted to start a new thread because the issue here is a new one - it's no longer the drone/growl under load (which the new ujoints seemed to have fixed) but a consistent rear vibration at 55mph to 75mph.

So I got all the tires re-balanced and no change-actually the vibrations seem more pronounced.