R107 - Rear brakes on fire!!!

[Pie-Man]

Picked up the car after the starting problem had been rectified (see other thread!) ... driving down M3, smoke from both rear wheels, forced to pull over ... discs glowing! Limped home.

Inspection shows that both calipers had got extremely hot! Pads worn down to metal & distorted, piston boots carbonised/vapourised! Front brakes OK to stop vehicle. Once cleaned up, the drivers side caliper appears to have a hairline crack causing a small fluid leak. Passenger side OK.

Any ideas???? It had a full service at Hughes MB less than 500 miles ago ...

HELP!

 

[television]

Picked up the car after the starting problem had been rectified (see other thread!) ... driving down M3, smoke from both rear wheels, forced to pull over ... discs glowing! Limped home.

Inspection shows that both calipers had got extremely hot! Pads worn down to metal & distorted, piston boots carbonised/vapourised! Front brakes OK to stop vehicle. Once cleaned up, the drivers side caliper appears to have a hairline crack causing a small fluid leak. Passenger side OK.

Any ideas???? It had a full service at Hughes MB less than 500 miles ago ...

HELP!

This is what can happen when the car is left standing, I think that yours was out in all of the rain earlier in the year.

The components are very easy to change and not that expensive, you may have to shop around for a good price on the calipers.

 

[whitenemesis]

This is what can happen when the car is left standing, I think that yours was out in all of the rain earlier in the year.

The components are very easy to change and not that expensive, you may have to shop around for a good price on the calipers.

How does this happen?
For the pads to wear down to the metal constant pressure must have been applied?

Not doubting you Malcolm, just after understanding

 

[Mr Teddy Bear]

I'm only trying to be helpful here...........
If I intend to leave a vehicle parkedup for awhile I leave the parking
brake off and choc the wheels.
I assume that your SL has the top hat design of rear disc and ABS ?
If so would the h/brake sizing on have generated enough heat in the disc
to destroy the calipers ?
My point being is some thing either wrong with the ABS or alternatively
the pressure limiting valve ?

Tim

 

[television]

How does this happen?
For the pads to wear down to the metal constant pressure must have been applied?

Not doubting you Malcolm, just after understanding

I would have said that the pistons were so tight (rust maybe) that they would come out, under pressure but not be able to return to the clearance position, the hotter they got ,the more they stuck, the is no other answer, even though the rear brake only operate on 28% of the total pressure.

 

[whitenemesis]

Still not sure this explains it. Once worn down, no more heat? This sort of thing happens with air-brakes (default on) but not with hydraulic (normally off) systems.
Or am I totally off the mark?

 

[television]

I have heard of this fault many times, and I have never heard of ABS causing this, ever. the parking brake is separate and any heat would not transfer onto the calipers. The ABS is four separate lines and linked to the pedal.
Only by dismantling will he know

 

[hmang]

Still not sure this explains it. Once worn down, no more heat? This sort of thing happens with air-brakes (default on) but not with hydraulic (normally off) systems.
Or am I totally off the mark?

if the pistons / pads are seized /sticky and not returning.
every time you apply the brakes they move outwards little by little under hydraulic pressure.
almost as if on a ratchet

 

[Ultymate]

How could you have driven the car with either the parking brake and or the rear calipers siezed on until the discs are glowing red and a caliper cracks with heat surely you must have felt some serious lack of performance to say the least, sorry if I'm being critical but the question begs to be asked, not only that you then continue your journey.:-?

 

[Pie-Man]

How could you have driven the car with either the parking brake and or the rear calipers siezed on until the discs are glowing red and a caliper cracks with heat surely you must have felt some serious lack of performance to say the least, sorry if I'm being critical but the question begs to be asked, not only that you then continue your journey.:-?

Interesting point ... we certainly had not experienced any noticeable performance deterioration? Though we have not had the car for long.

My major concern is that the car went through a full service at Hughes of Beaconsfield very recently ... it has hardly done any mileage since then as it was back at Hughes for the (failed!) cold start issue for 4 weeks!

Am I being unreasonable to expect that the MB service should at least check pad life and brake function?

 

[Blobcat]

Interesting point ... we certainly had not experienced any noticeable performance deterioration? Though we have not had the car for long.

My major concern is that the car went through a full service at Hughes of Beaconsfield very recently ... it has hardly done any mileage since then as it was back at Hughes for the (failed!) cold start issue for 4 weeks!

Am I being unreasonable to expect that the MB service should at least check pad life and brake function?

I know it wasn't a Mercedes however a company Astra Estate I had had a similar problem just after a service. The main dealer overtightened the handbrake (3 clicks to on when it should have been 7). Whilst the handbrake was not fully on it was on enough to heat up the rear brakes boiling the fluid so I effectively had no brakes. Thankfully there was a nice farm lane to run up No damage other than boiled fluid and after a change and readjust the handbrake it was fine again.
So things like this can happen, if mine hadn't been serviced the brakes would have been fine...

 

[television]

Interesting point ... we certainly had not experienced any noticeable performance deterioration? Though we have not had the car for long.

My major concern is that the car went through a full service at Hughes of Beaconsfield very recently ... it has hardly done any mileage since then as it was back at Hughes for the (failed!) cold start issue for 4 weeks!

Am I being unreasonable to expect that the MB service should at least check pad life and brake function?

There is no way on a service or normal check to show if the rear calipers are backing off or binding, it is not a test that one normally does

 

[hmang]

There is no way on a service or normal check to show if the rear calipers are backing off or binding, it is not a test that one normally does

what?
they wouldn't:

inspect tyre for wear and damage
wiggle the wheel bearings
and spin the wheel to check for binding

that's outrageous on a FULL SERVICE

 

[television]

what?
they wouldn't:

inspect tyre for wear and damage
wiggle the wheel bearings
and spin the wheel to check for binding

that's outrageous on a FULL SERVICE

I have seen the front lifted and bearings checked, and the wheel spun when its up, but as in this case the rear must have been just visual, rear wheel bearings hardly ever need attention

 

[Mr Teddy Bear]

Hi Pie-Man,
Have you had new pads fitted recently ?
Sounds like bad maintainance and servicing to me.
The Pad Backing Plate can quite often need a few thou' taking off with a smooth file before fitting.
If your car is starting to age just fitting new pads with out overhauling the caliper and if it slides with a single piston inthe caliper, the carrier as well
is not sufficient.

Best Regards,
Tim ( Happy CLK Owner)

 

[wireman]

I have known this problem on several cars, caused I think by the rust that builds up on the edges of the steel plate (and / or calliper slots) on the back of the pad this causes the pads not to be pushed back by the running disk, they dont move much and pad/disk contact under the slightest pressure will cause the brakes to bind and the disks to dissipate killojoules of energy and heat the disk to high temperatures quite quickly. You dont notice the drag whilst driving, it is very small compared to the torque available from the engine. Lifting the wheel and hand turning it should give an indication of the amount of drag, there should be next to none.
The temperature of all the brake parts will affect how and when it sticks making diagnoses from inspection a tad difficult, suffice it to say there should be some vertical play on the pad in its slots (which may be taken up by anti rattle springs making the assesment of play well neigh impossible), the only way to be certain is to dismantle, clean and reassemble.

On my rover 25 a front wheel bearing was cooked along with the disk and caliper after just 10 miles of motorway driving (It stank and I stopped just as soon as I was sure that it was my brakes I could smell), I still do not know if the CV joint has been damaged since it still works after 10,000 miles. This occurred two days after a full brakes service by those reputable guys at SGL Rover (now defunct) This braking system is a Honda design.

It is difficult to argue with fact that the dealer should have seen a problem but the problem only manifests itself when you sustain higher speeds for a while and you probably wouldn't want them thrashing your pride and joy up the M6 just to see if it got hot would you?

GSF have some calipers at around £50 each as do Euro car parts, But neither list 107 bits.

 

[Pie-Man]

... that's outrageous on a FULL SERVICE

I think so too ... was just checking in case I was being too picky!?! :wink:

I would expect that a full service would inspect brake function and pad life!? There was literally nothing left of most of the pad material, which undoubtedly lead to the over-heating! So it now needs need calipers, discs and hoses!

I'm questioning what exactly they DID do on the service?

 

[Pie-Man]

... Have you had new pads fitted recently ?

Nope! And there lies the problem methinks!?!
Do they only check pad wear when a warning light comes on?!
Jeeeez ... even the guy that services my 1988 Volvo 240 wreck would check the pads!!!!

 

[television]

Nope! And there lies the problem methinks!?!
Do they only check pad wear when a warning light comes on?!
Jeeeez ... even the guy that services my 1988 Volvo 240 wreck would check the pads!!!!

Most early cars do not have rear sensors fitted, as said the thickness of the pad is OK to due visually. if the pistons were seized just partially they would soon go down to the metal. some makes of caliper have limits on the amount of travel, as also said the sliding mechanisms of single piston brakes also needs to be in good order, its so sad yes, after your other problems, but a hard one to put the blame on someone

 

[Mikesmerc]

Every Mercedes I have owned has had their calipers sieze in one way or another. All these cars were parked up 3-6-12 months at a time, 1no 107, 2no 112s, 3no 123s, 1no 124, and 1no 126. I have stripped the calipers each time to find a black tar like substance on the piston or rust on the rim of the caliper where the dust cap sits. Have always sandpapered the rim(not the piston or sleave of the caliper) and generally just cleaned them up. The result being a piston that needed a great pressure to be popped out by using the brake pedal or compressed air to a clean piston being pushed back in by light pressure of both thumbs.
As Malcolm says the pistons dont relax, the disc heats up and expands making things worse, one more touch of the brakes and your back to square one. My 126 boiled the fluid leaving near to no brake left at all.
My 107s were cleaned up about 10years ago by me and are showing signs of having to be done again, mostly because of idleness. When replacing pads the pistons should give only medium resistance when being pressed back, any firm pressure and your in to a strip down, wasting your time fitting pads.
It is quiet a simple job if you are any way handy.
Well thats my bit, hope its of some use.
Regards
Mike