Hyundai Repair: Odd brake noise, transmission oil cooler, american mechanics

Question
Hello,

I have a US spec vehicle and I am living outside the US right now.  I am sick of these local mechanics, and have a quick question.  When I  brake when driving downhill, or on the highway my rear brakes will make this clicking and squealing sound.  The squealing sound is more pronounced.  Now, I took the vehicle to the Hyundai dealership and they said it needed new brakes (they just drove it and duplicated the problem and looked at the brakes with a flashlight).  Since I didn't want to pay over $400 for brake pads, I decided to go on base and check out the American mechanics.  The Americans did a full brake inpsection and told me my brakes where fine.

I have a serious problem.  That brake sound is annoying, and it can't be safe.  I think they are overheating.  It only sounds like it is coming off of the passanger side rear brake assembly.  If the vehcile stops for a bit they will cool off and the sound will go away.  I just have to try and not ride them.  I changed my driving habits a bit to see if that helped, but I still get the sound.  The mechanic says my pads are at 50%.  The sound is present when I start moving from the stopped position for a little bit.  I suppose I could email a video clip of it doing it..

I honestly have no reason to trust either set of mechanics.  One told me my check engine light was due to local weasels eating a spark plug wire, which I told them it was the 02 sensor (I was right, and down $250 on a worthless repair).  The Americans said I had a leaky transmisson gasket, while I had a leaky transmission oil cooler.  The Germans then told me that was a power steering oil cooler!  I can't trust either group!  Help!

Oh, and one last thing.  The pads where always kinda grumbly.  They made a soft sound since I owned the vehicle.

Answer
The fact that there's a noise doesn't necessarily indicate there's a problem that needs to be corrected.  To determine this, however, it's necessary to look at the vehicle and determine the cause of the noise.

Squeaks or squeals that occur when the brakes are applied are typically nothing more than an annoyance.  It's considered normal for disc brakes to do this from time-to-time, and drum brakes often do this because the dust accumulates in the drum.  As long as your braking ability isn't affected, there's nothing unsafe about this.  The disc brake squeal won't affect your braking ability, and the worst you'll probably get out of the drum brakes is that they'll grab a little bit.

If you hear a grinding type noise when the brakes are applied, this is usually caused by either rust on the rotor/drum braking surface, or a pad or show worn to the backing plate.  The rust isn't a safety issue unless it gets to the point where the rotor/drum begins to flake part of the surface off.  Wear to the backing plates, however, is a significant issue with safety and braking capability.

If you're hearing a squeaking sound when moving independent of depressing the brakes, it's possible that the brakes on one or more wheel are staying applied.  This can occur due to a hydraulic problem, overadjusted drum brakes, a caliper binding issue, or rust buildup on the pads causing them to stick in place in the caliper.  It's also possible that the noise is completely unrelated to the brakes.

Similarly, if you hear a squealing sound independently of the brakes being applied, it could be a pad shim or the wear indicator rubbing the rotor.  The pad shim will have no significant consequence, while the wear indicator would indicate it's time to replace your pads.  Also, this noise could have nothing to do with the brakes at all.  It could be in any component that moves when the vehicle is in motion.

My advice is to ask those you know and get references for trustworthy and competent repair facilities.  You'll need a place that will correctly diagnose the noise and advise you on the consequences of whatever's causing the noise.  When you take the car in to be checked, tell them when the noise occurs and what it sounds like.  Let the shop determine whether it's related to the brakes.

One possible scenario is that both shops have been competent and honest.  For example, if your brakes squeal when applied and you have about 50% pad life left, then there's probably no imperative need to replace them.  On the other hand, if you want the noise to go away, the dealer may know of something that will occur with the pad replacement that will make it go away.