Hot Brake Disc

[WrathOfKain]

Here I return to Valhalla to again consult the Viking Gods to steer my longship to the new lands.

Had a bit of screeching on driver side and AA chappie thought it was maybe the pads. Took to Halfords and they checked it over and didnt find any issues.

Again noted screeching so took to local indi and again they didnt find any issue. They checked calipers etc.

After going for a wee run for the sake of the DPF noted the driver side rear brake disc was hot. Repeated the run and temp gun showed 350 degrees C .... all the others were fine. It doesnt appear to happen all the time.

Got my Vida/Dice onto it and there was a BCM-0136 Brake Pressure Sensor 1 & 2 Signal outside its permitted range. I cleared it and it didnt come back. Took for a run, same brake disc hot again but no repeat of the fault.

Any ideas ?

[ommony]

Almost certainly a sticking rear caliper. I've just been through this and it is apparently pretty common. I got a rebuild kit and that sorted it out. You could of course get a rebuilt or new caliper instead.

Don't leave it too long as if it's similar to mine, it went from 'a bit sticky' to almost completely locked on in no time at all.

[BilboBagginss]

I had the same on my V70 - went from being OK to locked solid virtually overnight (noticed on a 30 mile trip). New calliper sorted it

Car was approx 12 years old and over 200k miles so can’t really complain as it was the original calliper.

[WrathOfKain]

Thats what I and the AA chap though but the Halfords and the Indy apparently didnt seem to find anything. What is weird is the when there is a screech its on the passenger side but the hot disc is on the drivers side. Mind you it doesnt always screech but the disc will be hot.

[Tannaton]

+1 for sticking calliper, quite a common problem. If you’re used to working on brakes you can usually strip it, clean it and reassemble it and it will be fine.

Tip - once you have removed the calliper but before you undo the hydraulic hose - pump the brake pedal to push the piston out.

When you reassemble it’s a good time to change the brake fluid to all four corners.

[SwissXC90]

I had high pitched squealing on my XC90, sometimes at low speeds, some times at motorway speeds

Was a sticking caliper on the front right - but it was really hard to diagnose where the sound came from. As a driver, you couldn't determine the source of the noise.

One day I went out with my digital thermometer after a drive home and checked all four wheels, and the front right was distinctly warmer than all others. Like over 20°C warmer. Thus we knew it was the front right wheel.

Dealer disassembled, cleaned and lubricated the caliper.
No more squealing since.

Your hot disc will definitely be the culprit.

[ommony]

As others have said, it's very difficult to tell from the sound where the problem is. I thought I had a bad wheel bearing at first. Also, in the early stages, it was intermittent and unpredictable. It would seem fine at times and then would stick and be bad for a bit. Possibly down to expansion/contraction of the parts when they got hot? That didn't last, though, and before too long the caliper was stuck on hard.

Assuming it is a sticky caliper, you might get away with just greasing the slider pins, but at least on mine it was corrosion on the piston itself (despite the dust boot being intact) and once you have the wheel off, slider pins off, it's not a lot of extra work to put in new seals/piston/etc and have a fully rebuilt caliper. Seal/piston kits are cheap and you can do the whole rebuild without disconnecting the brake lines or anything.

It's also worth mentioning, of course, that the garages you took it to could be spot on and it's not a problem with the caliper. As it's on the rear, it could be a sticking/poorly adjusted parking brake shoe. It could also be a bad wheel bearing generating the heat (although I think you would hear that pretty clearly if it was bad enough to really heat up the brake disc).

So yeah, while the sticky caliper is definitely the prime suspect, don't go into it blindly assuming that is the case.

[WrathOfKain]

Thanks gents ..... wisdom as always. Had a look and there looks like some residue on the wheel.

I have the parking brake adjusters i am needing done so might get them to do that while they are in there:

https://www.ebay.co.uk/itm/321749453357?ul_noapp=true is it worth just getting a rebuild done on the rear calipers then ?

On the calipers is it worth a rebuild or just replacing them. Doesnt look like that much of a price difference ?

https://www.ebay.co.uk/itm/REAR-L-R-...4AAOSwWiNaojNc

or just get these:

https://www.ebay.co.uk/itm/FITS-VOLV...03b074c18e39d4

[WrathOfKain]

Originally Posted by ommony

As others have said, it's very difficult to tell from the sound where the problem is. I thought I had a bad wheel bearing at first. Also, in the early stages, it was intermittent and unpredictable. It would seem fine at times and then would stick and be bad for a bit. Possibly down to expansion/contraction of the parts when they got hot? That didn't last, though, and before too long the caliper was stuck on hard.

Assuming it is a sticky caliper, you might get away with just greasing the slider pins, but at least on mine it was corrosion on the piston itself (despite the dust boot being intact) and once you have the wheel off, slider pins off, it's not a lot of extra work to put in new seals/piston/etc and have a fully rebuilt caliper. Seal/piston kits are cheap and you can do the whole rebuild without disconnecting the brake lines or anything.

It's also worth mentioning, of course, that the garages you took it to could be spot on and it's not a problem with the caliper. As it's on the rear, it could be a sticking/poorly adjusted parking brake shoe. It could also be a bad wheel bearing generating the heat (although I think you would hear that pretty clearly if it was bad enough to really heat up the brake disc).

So yeah, while the sticky caliper is definitely the prime suspect, don't go into it blindly assuming that is the case.

The noise after the indy checking it had pretty much gone but still the heat was there. It did return on one of the runs i.e. the last one. ....... parking brake strangely enough is another problem as it takes a fair few clicks to get it to engage hence looking to get that adjuster put in.

[WrathOfKain]

Hopefully it is unrelated. Did a Vida/Dice scan again the pressure sensors did not come up but recently when it is doing the checks i have noticed the ABS warning light come on .... only during the scan ..... switch engine off on again and it dissappears ???