Brakes are burning...what to do?? - PeachParts Mercedes-Benz Forum

1goos4u · #1 05-27-2010, 06:59 PM

So the left front brake of my w123 has a bad tendency of dragging and getting quite hot, and eventually the wheel smells like burning brakes. Today I actually lost braking power due to overheated brakes. It seems after I apply the brakes firmly, the brake caliper does not release as it is supposed to. I tried replacing the caliper but this has not fixed the problem. What else could be the problem? I suppose my next step is master cylinder but are there any other more probable possibilities or any way to test to find out exactly what is causing this?

markho · #2 05-27-2010, 07:02 PM

i would check the vaccum pressure on the master cylinder to see if there are any leaks.

glenlloyd · #3 05-27-2010, 07:11 PM

Quote:

Originally Posted by 1goos4u

So the left front brake of my w123 has a bad tendency of dragging and getting quite hot, and eventually the wheel smells like burning brakes. Today I actually lost braking power due to overheated brakes. It seems after I apply the brakes firmly, the brake caliper does not release as it is supposed to. I tried replacing the caliper but this has not fixed the problem. What else could be the problem? I suppose my next step is master cylinder but are there any other more probable possibilities or any way to test to find out exactly what is causing this?

My 94 Golf liked to do the same only on the rear circuit (4 wheel disc), especially in the summer when it was hot. Ended up it was master cylinder since the calipers were not binding at all.

steve a

patbob · #4 05-27-2010, 07:31 PM

I've been told the rubber brake lines down to the wheels can sometimes act as one-way valves when they get old.

The quick check is to open the bleeder valve on the affected wheel and see if the brake releases. If it does, then something (probably the rubber line) is acting as a one way valve, else its probably the caliper that's sticking.

barry123400 · #5 05-27-2010, 08:54 PM

Well it's not the master cylinder or both wheels would be runnning hot. You can usually monitor your brakes by feeling the rim temperature with a finger after a drive or using a laser type thermometer.

1goos4u · #6 05-27-2010, 10:18 PM

Quote:

Originally Posted by barry123400

Well it's not the master cylinder or both wheels would be runnning hot. You can usually monitor your brakes by feeling the rim temperature with a finger after a drive or using a laser type thermometer.

Well I know it is the front right side brake as the wheel gets scorching hot and that is where the burning brake smell is coming from. Good point on the master cylinder...I was leaning toward something that would be isolated on the front right. I hadn't heard of a line working as a one-way valve but that is a possibility. I suppose worth a shot. I'll try to get that replaced and see where I stand.

layback40 · #7 05-27-2010, 10:50 PM

Its most likely sticking calipers. Bet the fluid has not been changed in years. Need to remove the caliper & carefully apply the brakes to see if the pistons come out at all. Sometimes if you put a little fluid on the piston sides on the outside it helps loosen them.

t walgamuth · #8 05-28-2010, 04:23 AM

I would check to see if the pads are pretty worn and if they are installing new pads and making sure they are not binding in the caliper may put the piston back into the caliper and working on a new area of the cylinder.

Sometimes simply getting the piston working in a different area of the cailper will do the trick.

remark123 · #9 05-28-2010, 07:55 AM

Almost a surefire fix is to replace the brakeline as has already been suggested. I have had this happen a couple of times, especially with cars over 10 years old, the inside wall of the rubber hose collapses allowing the pressure from the M/C to flow to the caliper, but the fact that there is almost no pressure exerted from the piston to force the rubber hose wall back, thus the fluid is blocked and the piston will not move.

Just my .02 cents worth!

KarTek · #10 05-28-2010, 08:03 AM

I'll give a strong 3rd on the rubber brake lines. I had a Chevy pickup that was only 13 years old and it was doing the same thing. Replaced the lines and it fixed the problem like magic!

Now, I'm replacing the rubber lines on all my vehicles since they're all over 10 YO. Pretty cheap insurance.

t walgamuth · #11 05-28-2010, 08:58 AM

In my experience the one way brake line failure is very very rare in a benz. I am pretty sure in the 30 benzes I have had, mostly old, I have never had it happen. Siezed calipers are fairly rare too but I have had a handful of them.

benhogan · #12 05-28-2010, 09:46 AM

Your problem is the flexible brake lines. The rubber has swelled and is restricting fluid flow.

Replace the lines and your problem will go away.

t walgamuth · #13 05-28-2010, 10:13 AM

Quote:

Originally Posted by benhogan

Your problem is the flexible brake lines. The rubber has swelled and is restricting fluid flow.

Replace the lines and your problem will go away.

Ahhhhh, I used to be so confident.

benhogan · #14 05-28-2010, 12:20 PM

Quote:

Originally Posted by t walgamuth

Ahhhhh, I used to be so confident.

I called my urologist today. He picked up and said..."can you hold?"

1goos4u · #15 05-28-2010, 01:02 PM

Seems the consensus is w/ the rubber hose. I'm ordering one soon but unfortunately this means I'll have to take a different car to New York for Memorial Day...I was really looking forward to driving the Benz on another road trip.

I'll update once I get the new part on.