Squeaky brakes

[firstmercedes]

Had my 11 plate C220 W204 major service, front brakes replaced and MOT 3 months ago.
Recently noticed brakes squeaking loudly when used after about 10 minutes driving.
Took back to same garage and they advise rear brakes need replacing.
Really? Only 3 months after MOT?
I have no warning lights to suggest brake ware.
I am taking to another garage for second opinion.
Am I really this unlucky?

 

[zipdip]

Well brake noise can be a number of things,the first is brake dust,for some years car makers have fitted soft pads these afford quick braking but create dust that can make a noise when braking,or it is the rear shim fitted behind the brake pads ,now here we get into a grey area most old guys like me have always used a tiny amount of copper grease on this shim to stop any noise,but some frown on this practice as grease and brakes could be a problem ,but I have never had a problem,last you get brake noise when the pads are worn right down ,I doubt it could be that after a MOT,it could be that on the edge of your brake discs there is a ridge of rusted cast iron which if it gets big enough will contact the brakes and make a noise,this generally means new discs and pads,but you could just get a hammer and just carefully chip away the ridge and get yourself some breathing space before you need to spend out on new disc's

 

[markjay]

1. Not sure what is the connection between the MOT and the rear brake pads wear? The MOT tests the ability of the brakes to stop the wheel rotating, not the thickness of the pads or their state of wear. And on many cars the thickness of the pads is not even visible with the roadwheel in place. Add to this the fact that MOT only guarantees the functionality of the brakes at the time of testing... as soon as you drive out of the MOT station you are on your own.

2. Not sure about the W204, but many cars only have pad wear sensors on the front brakes (and not the rear). Someone else on here might know if your 2011 W204 is equipped with rear brake pad thickness sensor.

3. If you brake with the windows open you should be able to hear if the squeal comes from the front brakes or the rear brakes? If it's from the front, then ask the garage to apply a very thin layer of brake paste (aka copper grease) to the back of the front pads.

 

[Martygt550]

Take the pads out and clean them,clean the calipers as well then refit the pads using ceramic brake grease, you could also sand the surface of the pads lightly to remove any glazing that may have occurred
(Mercedes recommend NO grease be used, fit the pads dry)

 

[OneForTheRoad]

why not ? 3 months after the mot , ive recently fitted bendix pads to the front and they had no central slot for the dust , and sqealed like a pig, i replaced them with pagid which do have a slot and they are now silent.

 

[firstmercedes]

1. Not sure what is the connection between the MOT and the rear brake pads wear? The MOT tests the ability of the brakes to stop the wheel rotating, not the thickness of the pads or their state of wear. And on many cars the thickness of the pads is not even visible with the roadwheel in place. Add to this the fact that MOT only guarantees the functionality of the brakes at the time of testing... as soon as you drive out of the MOT station you are on your own.

2. Not sure about the W204, but many cars only have pad wear sensors on the front brakes (and not the rear). Someone else on here might know if your 2011 W204 is equipped with rear brake pad thickness sensor.

3. If you brake with the windows open you should be able to hear if the squeal comes from the front brakes or the rear brakes? If it's from the front, then ask the garage to apply a very thin layer of brake paste (aka copper grease) to the back of the front pads.

The reason for the MOT comment was that I thought they needed to provide advisory info on items that were close to needing replacement to keep the vehicle legal.
I didn't think that maybe the rear pads were not on sensors so thanks for input on this.
I have tried braking with window open and it's really difficult to tell. I really though front but on taking car back to garage they have suggested rear.
Really appreciate the input on this.
Car will be back in my tried and trusted local garage tomorrow (Oh why did I try another one just because it was a few quid cheaper on big service).

 

[Stratman]

Are the discs worn below minimum thickness? Thinner discs can get to quite high temperatures and cause surface glazing, discolouration and cracking, symptoms of overheating.

 

[markjay]

The reason for the MOT comment was that I thought they needed to provide advisory info on items that were close to needing replacement to keep the vehicle legal...

1. They are not obliged to check anything that is not part of the test requirements and not immediately obvious. And the wear level of the brakes is not part of the MOT test, only their actual performance on the day.

2. They are not allowed to remove wheels or any panels, undertrays, etc, so if they can't access or see something then they have to leave it at that and can not investigate further.

3. Even in the event that they do spot a potential issue, there is room for discretion regarding whether it merits an advisory or not. I have seen cases where a car got an advisory in one year, then didn't get an advisory the following year, in spite of no repairs having been made during the period between the two MOTs.

So in short, I obviously don't know the state of your brakes, but the fact that the MOT tester didn't make any comments is not in itself proof that they were not close to their wear limit at the time of testing.

 

[firstmercedes]

1. They are not obliged to check anything that is not part of the test requirements and not immediately obvious. And the wear level of the brakes is not part of the MOT test, only their actual performance on the day.

2. They are not allowed to remove wheels or any panels, undertrays, etc, so if they can't access or see something then they have to leave it at that and can not investigate further.

3. Even in the event that they do spot a potential issue, there is room for discretion regarding whether it merits an advisory or not. I have seen cases where a car got an advisory in one year, then didn't get an advisory the following year, in spite of no repairs having been made during the period between the two MOTs.

So in short, I obviously don't know the state of your brakes, but the fact that the MOT tester didn't make any comments is not in itself proof that they were not close to their wear limit at the time of testing.

Okay, fair enough, but after paying close to £1K for a full service plus transmission service plus front brakes plus MOT I sort of hoped I was okay for a few months.

 

[markjay]

Okay, fair enough, but after paying close to £1K for a full service plus transmission service plus front brakes plus MOT I sort of hoped I was okay for a few months.

Interestingly, with Mercedes Benz, the brake pads thickness are supposed to be checked at each service, A and B, but the road wheels are only removed for Service B, which is every other year.

So if the garage carried-out a Service A, then I suppose they could argue that the it was difficult to fully assess the condition of the rear pads with the road wheels in place, but if they carried-out a Service B, then there's no excuse for not spotting that the rear pads were nearing the end of their service life.

 

[zipdip]

Well all the MOT garages I have used do point out if the brake pads are getting low,tyres that are getting near the limit,these are not recorded as a advisory,they are of course after follow up work,as we are owners of a Mercedes cars you can by using certain MOT garages get advisories for having the underneath of the car shrouded,I found one that does not do that,it just depends on the garage,I have had them point out a small chip in the front screen nowhere near the fail area of the MOT but good that they told me,as for the op's brake noise I think we have covered all the reasons you can get noise,I hope he gets it sorted.

 

[markjay]

Well all the MOT garages I have used do point out if the brake pads are getting low,tyres that are getting near the limit,these are not recorded as a advisory,they are of course after follow up work,as we are owners of a Mercedes cars you can by using certain MOT garages get advisories for having the underneath of the car shrouded,I found one that does not do that,it just depends on the garage,I have had them point out a small chip in the front screen nowhere near the fail area of the MOT but good that they told me,as for the op's brake noise I think we have covered all the reasons you can get noise,I hope he gets it sorted.

That was my original thinking as well, but then the OP explained that the MOT was done as part of a major service.

And if it was a Service B, then definitely the wheels should have come off and pad thickness inspected.

 

[Petrol Pete]

OP, you have told us '3 months' not how many miles since MOT ? Time means nothing in this case , it will be the mileage the car covered in those 3 months.
But as others have pointed out the brake pads might (should) have been checked in this case, maybe they were and were found to be OK but you might have put 6K miles on them in the last 3 months for all we know.

 

[firstmercedes]

OP, you have told us '3 months' not how many miles since MOT ? Time means nothing in this case , it will be the mileage the car covered in those 3 months.
But as others have pointed out the brake pads might (should) have been checked in this case, maybe they were and were found to be OK but you might have put 6K miles on them in the last 3 months for all we know.

Have put on 2800 miles since MOT

 

[Petrol Pete]

Have put on 2800 miles since MOT

As said, IF the garage did a proper wheels off brake pad measurement test they should have given you a measurement and/or a recommendation to change them soon. Your mileage based on your figures is about 11200 per year so not too drastic.
The worn pads should have set the warning light off (last resort), unless of course the wires have been cut and twisted together which is surprisingly common.

 

[Flackadder]

Have had squeaky brakes ever since I got my car. Over time all the discs and pads have been changed my MB due to wear etc. Still squeaks. Though, they do not squeak when the windows are closed ;-)

 

[firstmercedes]

Update:
The story in brief - Had new front disks and pads fitted 3 months ago (as well as MOT, big service and transmission service). After 3 months there was loud squeaking seemingly coming from front brakes when hot. Took car back to garage who advised squeak was actually from rear, needed new rear brakes, would cost me £300 and they could fit that same day. A bit shocked, I collected the car declining the new brakes.
I took the car to another garage for second opinion.
They provided a report stating squeak was coming from front and that the rear were fine with plenty of life left.
Somewhat perplexed (actually really annoyed) I returned to the original garage who got one of their guys to come on a drive with me. Sure enough, after about 10 minutes the screeching started and the guy immediately diagnosed problem with front brakes possibly something to do with ceramic deposit or something.
So, car booked in, front brakes changed - they advised a not seen before gouging problem and will return old set to supplier for analysis (like I could care less).
My main issue, which they couldn’t really get to grips with is if I had believed their diagnosis, I would have spent a further £300 for not required rear brakes and still had squealing front brakes.
So, eventually, after numerous phone calls and visits to this garage, and having to involve another garage to get a correct diagnosis the problem is fixed - at least they washed the car.

 

[zipdip]

Tough start to owning your car,find a decent indy near you I am sure a member can point you in the right direction,a shame this took so long to get put right,and of course the cost,at least the car wash saved you £10 down the hand car wash