Rear humming noise after towing across country

[clawfilm]

I just recently moved from Chicago to LA and towed U-haul's 5x8 trailer. I did pack the trailer AND my 4runner to the ceiling but was pretty sure I was still within the recommended weight ratings. I am now second guessing that, as now when the car is empty, I'm getting a pretty noticeable hum. It begins as soon as I start moving the car and increases as I accelerate. It almost sounds like regular tire noise amplified on both my rear tires. Also it's sounds like I removed any sound dampening material in the trunk or back doors.

I have a 2007 Limited with 104k miles. I also just had my driveshaft replaced about 4k miles ago.

I've searched hums but had a hard time finding anything relating to towing specifically. Is there anything I can take a look at to see if it's the culprit BEFORE bringing it in for service? I just used up my warranty by hitting 100k, so I'm trying to limit my costs of playing games with the stealership.

Thanks in advanced!

 

[DC runner]

Ok, before I give a bad prediction; lets isolate it.

If your truck is a v6, without full time 4wd; then place two jack stands on the back and have your gf/mom/dad/buddy put it in drive and get up some speed on the rears. Listen. If the noise is there, it isn't road noise.


Now. For what I think happened: You don't say if it is a v6 or v8, but since the v6 is the more numerous model; I will go on with the assumption it is a v6.

It, honestly, sounds like rear diff noise. As in rear diff going out. Isn't the worst thing, but you want to catch it before it locks up. If it locks up it will destroy all kinds of stuff.

It can't be tire road noise if it starts immediately, but that is how diff noise shows up.

It could also be a dragging brake, perhaps, but that also needs a bit of speed to be apparent. I vote rear diff or rear axle issue.

 

[WXman]

Lots of times this is going to be your differential bearings going out. First thing I would do is pull the drain plug and see if metal bits fall out. You want to make sure you don't have pieces of ring gear or pinion gear teeth floating around. If the fluid that comes out looks good then button it back up and refill with the proper fluid and plan for a bearing replacement. A specialist will have to tackle that job. Only good mechanics should try that job in the driveway.

 

[ebg18t]

Does the sound go away if you turn right or left like a worn wheel bearing?

 

[clawfilm]

Thanks for timely replies.

I'm sorry that I didn't mention that I had the V6 model. You are correct.

The noise is pretty consistent and doesn't change much on turns. It only increases and decreases with speed. I have a feeling it's and axel or rear dif issue as well.

It also seems that my acceleration isn't as quick as it used to be. I'm not sure if that's just in my head due to being paranoid about the sound coming from my trunk. Would a weak rear dif cause less torque while accelerating on the highway?

Last question, I do plan on getting started with some mild mods for camping/backcountry trails, should I look at upgrading my rear dif if that is in fact what's causing the issue?

Thanks again!

 

[WXman]

Another possibility is failure of the parking brake shoes. Have seen this many times before. You could pull the drums and see. It'll be instantly noticeable if so.

 

[clawfilm]

I'll check that as soon as I get off of work . Thanks for the suggestion.

I hope it's something simple...

 

[BlazeRunner]

After changing my diff fluids, I noticed a large decrease in road noise and random rear vibrations... my rear diff looked a tad low when I drained it though.
it could also be wheel bearings making that noise

 

[gshadow325]

I would Jack up one side of the truck and turn the wheel to see if it moves freely, then theother side. You are checking if the brakes or parking shoes are binding. If you have not used the parking brake from the time you left Chicago till now, then probably rear calipers seized up. The pads are probably low and with the trailer, the piston might be extended too far and got stuck. This would explain gas mileage too.

Now go find the problem and report back.

 

[zopperman]

I would Jack up one side of the truck and turn the wheel to see if it moves freely, then theother side. You are checking if the brakes or parking shoes are binding. If you have not used the parking brake from the time you left Chicago till now, then probably rear calipers seized up. The pads are probably low and with the trailer, the piston might be extended too far and got stuck. This would explain gas mileage too.

Now go find the problem and report back.

I'd be interested to hear the results of this. I haven't heard of many rear calipers seizing on our trucks, just the fronts which were designed by morons.

 

[WXman]

I'd be interested to hear the results of this. I haven't heard of many rear calipers seizing on our trucks, just the fronts which were designed by morons.

ALL of my calipers were replaced or rebuilt around 70K for the seizing issue.

Also, the specific issue with the rear parking shoes that I've seen is that they can literally fall apart. The shoe material can detach from the shoe and cause noises and all kinds of issues. I've taken drums off before and the stuff just hit the ground. Toast. So I think he needs to do more than jack the truck up. I think he needs to pull the drums and inspect everything and adjust the shoes properly. Then go from there. Hopefully it's not his diff. bearings. That'll get expensive.

 

[gshadow325]

I'd be interested to hear the results of this. I haven't heard of many rear calipers seizing on our trucks, just the fronts which were designed by morons.

My right rear was seized. I had abnormal pad wear, bad fuel economy, rust on the rotors where the pad is supposed to grip, and a humming screeching noise. I threw in the towel and dived right in and just changed everything out. From pads to rotors to fluid. Truck stops much better now too.

Op: also a note, the rear 3 pads were at 25 to 30% left except the one that was frozen it was at 2%. I think the low pads and worn rotors contributed to the frozen caliper. I never replaced my calipers. I pushed then back in, cleaned them. Made them come back out by pumping the brakes and pushing them back in. To check the travel of the pistons. They moved and worked fine, it's been close to 5000 miles since.

 

[anotherrunner83]

how many miles are on your tires? could you have hit a wear mark and that added noise? i'd start with really simple stuff. tire pressure okay? throw a wheel weight in the journey?

i did have a diff go out one one of my old runners. it was a constant hum and slight vibration. if your tires check out, i'd change the fluid and see how much "stuff" is on the magnetic drain plug. if you have anything more than what looks like a silver powder, as in you can make out any individual pieces, you may have some diff damage.

 

[clawfilm]

Thanks for the interest and keeping this thread going. I just got the call back from Santa Monica Toyota and they said my diff is shot. They said it was mostly likely due to my towing... Again, I felt like I was way under the recommended limit. I did however take I-70 through Colorado. I'm pretty bummed that towing was the only culprit. They are quoting me $2,200 for a new rear diff. I'm heading over there at the end of the day to get the official paperwork but not sure if I'm going to have them do it or not.

I do want to start doing more trail riding and am wondering if this is a good opportunity (saving money) to start modifying my rear diff now? Should I go else were and get upgraded parts? Rear lockers, etc...? I'm pretty new to this and have lightly researched this topic.

The car has 104k miles and hope that it can take us to 300k without too many maintenance costs.

 

[zopperman]

Thanks for the interest and keeping this thread going. I just got the call back from Santa Monica Toyota and they said my diff is shot. They said it was mostly likely due to my towing... Again, I felt like I was way under the recommended limit. I did however take I-70 through Colorado. I'm pretty bummed that towing was the only culprit. They are quoting me $2,200 for a new rear diff. I'm heading over there at the end of the day to get the official paperwork but not sure if I'm going to have them do it or not.

I do want to start doing more trail riding and am wondering if this is a good opportunity (saving money) to start modifying my rear diff now? Should I go else were and get upgraded parts? Rear lockers, etc...? I'm pretty new to this and have lightly researched this topic.

The car has 104k miles and hope that it can take us to 300k without too many maintenance costs.

ARB drop in air locker!!!

 

[WXman]

By "new axle" they do mean new bearings and gearset in the 3rd member, right? $2200 sounds WAY too high for that job. Like, three times too high. My opinion is to find a reputable 4x4 shop in your area and let them give you a quote.

And yes, if you're going to install a locker this would be the perfect time to do it.

 

[ebg18t]

Order a assembled 3rd member from ECGS and have it dropped in. Upgrade for less than toyota wants for stock..

 

[clawfilm]

By new axle they mean the entire rear diff. They have the part listed at 1512.02 (Toyota Parts - Toyota Parts Superstore)

They said they found metal mixed in with the fluid and didn't bother actually opening the diff. I guess it's less fuss and faster to just get the entire part.

I did however go down the road to a place called dirty parts. I found them recommended on this forum for West LA. They are checking on their end how much these parts would cost tomorrow. I'm not sure if it will be more efficient to have them rip apart my entire rear diff and then rebuild what's actually wrong or pay a few hundred more for a brand new assembly.

I'm also not sure I'm understanding the differences in the items being recommended by you guys. I can get an ARB air lock for $1100 or a OEM rear diff (are those the same things?) for $1512.02 (or $1072 from toyotaoempartsworld).

On top of all this my struts are leaking so it looks I'll also be upgrading my suspension while I'm at it.

 

[gshadow325]

This just dawned on me. Did you ever change out any of the fluids in the front and rear Diff and transfer case before this failure? I ask because I am considering towing a pop up camper from Philadelphia to yellow stone and back next summer.

 

[cdthiker]

Thats rough news..... here is another vote for letting some one else give you a price quote.
Toyota dealerships are often slammed and the techs are under pressure to do things fast and not always well..... get a seccond quote and take it to another shop find a good 4x4 shop or import shop in the area and spend some cash up front then you have a second view point to go off of.
good luck