Hot brakes and humming/roaring noise

[jsean]

New issue on the 05 Corolla that a bunch of you helped me with during the master cylinder project a few weeks ago.

I noticed some groaning/roaring/humming sound over the weekend. It’s coming from the left side of the vehicle - thinking it’s the LF Moog wheel bearing I replaced about 23k miles ago. No biggie - ordered a replacement off RA. I got a LR wheel bearing also - as a just in case - because they’re cheap and I for the life of me couldn’t tell if it was LF or LR.

This morning I pulled into work and I could smell hot hot brakes. LF rotor on my commute seems to be getting a bit blue on the edges from the heat.

I ran in, grabbed an IR thermometer and came back out. So about 5 mins after being parked, LF rotor/caliper measured 249F. The only rim that was hot to touch.
RF rotor/caliper measured 94F.
RR drum measured 90F and LR drum measured 86F.

So what’s going on with the LF corner? Do I have a bad wheel bearing and a bad brake caliper piston?

The humming/roaring indicates the wheel bearing and the hot caliper/rim indicates a bad caliper.

Could a bad wheel bearing alone could cause the hot brake temps in that corner?

 

[D60]

A bad wheel bearing can certainly run hot but I don't know how much of that will translate into the rotor swept area. Given your temps I'd almost think you have a brake problem

HOWEVER if the wb is sloppy it'll cock or kick the rotor, causing it to drag on the pads.

I'd elevate that wheel and check for play. Then spin the wheel. Hopefully you find resistance. Pull the wheel and maybe crack the bleeder. Does resistance change? Then you may have to pull the caliper and see if it now spins freely.

Also with wheel off try to get temp readings at hub center vs outer edges of rotor (assuming you got it hot again)

 

[jsean]

A bad wheel bearing can certainly run hot but I don't know how much of that will translate into the rotor swept area. Given your temps I'd almost think you have a brake problem

HOWEVER if the wb is sloppy it'll cock or kick the rotor, causing it to drag on the pads.

I'd elevate that wheel and check for play. Then spin the wheel. Hopefully you find resistance. Pull the wheel and maybe crack the bleeder. Does resistance change? Then you may have to pull the caliper and see if it now spins freely.

Also with wheel off try to get temp readings at hub center vs outer edges of rotor (assuming you got it hot again)

Thanks. I’ll post back later today.
If the wheel isn’t spinning freely, that’s a possible stuck caliper correct?

Also, could the roaring noise be created by the bad caliper?

I couldn’t get the wheel to wobble when I on in it at 3 and 9 positions as well as 6 and 12 positions. It roars pretty clearly and it doesn’t go away when I shift from drive into neutral.

 

[D60]

Thanks. I’ll post back later today.
If the wheel isn’t spinning freely, that’s a possible stuck caliper correct?

Also, could the roaring noise be created by the bad caliper?

I couldn’t get the wheel to wobble when I on in it at 3 and 9 positions as well as 6 and 12 positions. It roars pretty clearly and it doesn’t go away when I shift from drive into neutral.

Well a bad bearing will often get very stiff before it progresses to I-ate-myself and then it gets VERY loose

So, absent play (which is an obvious sign) you'll need to eliminate the caliper (and hose) from the equation. Check slider pins or abutment clips in addition to caliper pistons.

I wouldn't typically expect a hung caliper to cause a roaring noise, but yes, there are situations where it's possible

I'd love to blame Moog here but you'll just have to dig a little further.

Let us know!

 

[ElectroMechanoMan]

That really sounds like a bearing problem. Give the wheel aspi and listen to the bearing with the old screwdriver stethoscope trick. If it is bad, you will hear it load and clear.

 

[D60]

That really sounds like a bearing problem. Give the wheel aspi and listen to the bearing with the old screwdriver stethoscope trick. If it is bad, you will hear it load and clear.

I agree. And sometimes it's difficult to tell until you have the bearing in-hand. Of course ideally you don't want to go that far without a solid educated guess, ie remove the bearing on a whim only to find it's fine

 

[jsean]

Well a bad bearing will often get very stiff before it progresses to I-ate-myself and then it gets VERY loose

So, absent play (which is an obvious sign) you'll need to eliminate the caliper (and hose) from the equation. Check slider pins or abutment clips in addition to caliper pistons.

I wouldn't typically expect a hung caliper to cause a roaring noise, but yes, there are situations where it's possible

I'd love to blame Moog here but you'll just have to dig a little further.

Let us know!

Ha! That’s good to know on the wheel bearings. I wonder if I’m just hearing the beginning of a failing wheel bearing. I’m not sure if a faulty brake line/caliper could cause the roaring sound?

Couple of things I was able to do over lunch:
1. Jacked the front end up and that LF wheel doesn’t really spin unless unless I force it to rotate.
2. Putting the car in drive with the front wheels up - the RF wheels spins like I’d expect it to. LF wheel won’t budge, even if I use a 2x4 to try and get it to move.
3. That LF rotor is blue - I think it’s getting heat treated as things stand

I’ll check out the wheel once I get home if I can get it to be free by cracking open the bleeder. For my understanding, if I crack open the bleeder and the wheel rotates - that’s indicative of a bad hose? And if I notice no changes even with the bleeder open, then it’s a bad caliper?

Edit: caliper pins were last greased about 3k miles ago in mid March when I changed over to the all season tires. The pins were freely moving when I checked them during the master cylinder project. I’ll check them again once I get home.

 

[Dave Sherman]

The noise could just be a dragging brake caliper. My CR-V would get sticky caliper guides if I didn't clean and grease them periodically, and if one got sticky, I'd get this noticeable howl after it got hot enough. Stepping on the brake would usually make the howl change or go away, but my IR thermometer showed that rotor was getting up to about 350 degrees.

 

[JohnnyG]

Stuck brake caliper piston.

 

[Silverado12]

It could be several things like a stuck caliper pin, flexible rubber hose, caliper piston, bearing, warped rotor.

 

[jsean]

The noise could just be a dragging brake caliper. My CR-V would get sticky caliper guides if I didn't clean and grease them periodically, and if one got sticky, I'd get this noticeable howl after it got hot enough. Stepping on the brake would usually make the howl change or go away, but my IR thermometer showed that rotor was getting up to about 350 degrees.

That’s good to know. I just verified - caliper pins are still good and move freely.

Opening the bleeder didn’t do allow the wheel to rotate freely.

 

[Lawnman23]

I had a collapsed soft line on one front of my Outback. Fluid would go in and squeeze the caliper but not be able to release causing the drag.

Had a very hot hub/wheel suddenly because of it. Replacement of that line fixed the issue.

 

[jsean]

Swapped the LF caliper out last night and I verified that the new caliper is retracting and confirmed that tire spins at idle.

I still have the issue of the hum though - I can hear it from about 30mph to just over 60mph after which engine noise/road noise/wind noise drown it out.
It seems to be a steady sound and isn’t dependent on whether I’m acceleration or coasting in drive or neutral. Did the bad caliper somehow cook the grease in the wheel bearing?

While I had the caliper and pads off yesterday, I tried turning the rotor as is. It felt really notchy to spin. Not sure if that indicates anything?

 

[D60]

It's possible. Sounds like you probably need a new wb, but don't spend money based on my armchair diag from afar.

The worst is on setups with a permanently attached spindle like trailers and full float rear axles. A stuck brake can effectively weld the race to the spindle, then you need a whole new axle housing.

 

[jsean]

I swapped the wheels around from side to side to rule out bad tires. Still humming and roaring on the left side. At this point, I’m contemplating just changing that hub and bearing assembly out. And if that doesn’t work, I guess I’m going to have to wave the white flag and take it to a shop.

 

[D1dad]

My trick is I always use OEM Honda inserts...and never have a issue..I just replace them one a year or so...

Well a bad bearing will often get very stiff before it progresses to I-ate-myself and then it gets VERY loose

So, absent play (which is an obvious sign) you'll need to eliminate the caliper (and hose) from the equation. Check slider pins or abutment clips in addition to caliper pistons.

I wouldn't typically expect a hung caliper to cause a roaring noise, but yes, there are situations where it's possible

I'd love to blame Moog here but you'll just have to dig a little further.

Let us know!

Yep. I just went through this. Left front bearing was bad and there was no doubt. I still had a slight hum and vibration, but the front right was tight, very tight. I swapped it out, because why not? Bearing was cheap, easy and I had one. Problem solved. The posters issue sounds like a clipper no do doubt. The last few bearings I’ve replaced, behaved nothing like bearings of old.

 

[PandaBear]

Ha! That’s good to know on the wheel bearings. I wonder if I’m just hearing the beginning of a failing wheel bearing. I’m not sure if a faulty brake line/caliper could cause the roaring sound?

I once install a caliper back with the line twisted into a knot. The caliper will brake but not release, and after a parking lot run the brake started smoking and gets real hot (not 249F hot but you can feel it like a 350F oven opening hot).

Maybe that's one thing you can check for by spinning only the left vs right side of the car up in the air. I think you can use a screw driver to lock one wheel of an open diff axle up in the air in position while the other side spin freely 2x as fast?

 

[jsean]

Updates for the day:
1. Installed a replacement LF wheel bearing - made no difference.
2. Took apart both rear drums and verified that the LR and RR bearings spin smoothly by hand. No notchiness or vibrations or noises that I could detect. Ditto with the wheels on.
3. Swapped out for the winter tires to eliminate all the all seasons. Growl/hum still present.
4. Jacked the front of the car up, wheels off the ground and put it in drive. Couldn’t detect any vibrations in the coil springs on either sides.
5. Verified that the brake lines are fine. New caliper on LF has fixed that issue for now.

I don’t think it’s the transmission because the noise is present in neutral and drive.
Unlikely it’s the engine because I can rev the engine in neutral while coasting and engine noise is independent of the growl/hum.
Not the tires and wheel bearings based on the above.

Time to call a shop?

 

[KrisZ]

The best way to check the front wheel bearings IMO is jacking up one side at a time and putting the car in drive. Usually you will hear the bad bearing right away from the inside, sometimes you have to give more than idle revs, but it doesn’t take much. Just make sure the vehicle is secure.

 

[jsean]

The best way to check the front wheel bearings IMO is jacking up one side at a time and putting the car in drive. Usually you will hear the bad bearing right away from the inside, sometimes you have to give more than idle revs, but it doesn’t take much. Just make sure the vehicle is secure.

Thanks for the suggestion. If I kept the RF wheel on the ground and the LF in the air with both back wheels on the ground and ebrake engaged - will that not cause the car to want to take off?

Is there a way to lock the RF wheel from rotating and transmit all the power through LF and vice versa?