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  #1  
Old 01-02-2009, 09:20 PM
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"hot" brakes smell at right rear wheel... ??

UPDATE - replaced brake pads on the rear several weeks and all is fine now - no more issues with the brakes. Thanks for all of the replies.

I have not noticed it until today, but when I stopped today to fill my car with gas, I got a whiff of "hot brakes". I smelled and it was coming from the right rear wheel well area (where I was standing). None of the others have the smell. I put my hand down near the wheel and it did not feel hot... warm, but not hot. My brakes work fine and there is no squeaking/scraping, etc, so wondering what could be going on.

(Yes, I checked and the e-brake is not applied).

Thanks for any information.
Btw - the car is a LWB W126 sedan.

Last edited by 86560SEL; 04-13-2009 at 02:30 AM. Reason: UPDATED
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  #2  
Old 01-02-2009, 10:13 PM
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Parking brake dragging.
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  #3  
Old 01-02-2009, 10:18 PM
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This is either a dragging parking brake or a stuck brake caliper piston. You need to jack up the wheel and turn it to see where it is dragging. You might have to pull the disc off to see if the parking brake parts have come apart.

Make sure you chock all the wheels before lifting one of the rears.

If this starts to really drag you may not notice the drag but you will soon notice the heat. The heat will discolor your alloy wheel by burning the paint off of it.

You might just need new brake pads.

Pooka
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  #4  
Old 01-02-2009, 10:34 PM
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A very common cause on these is a swollen brake hose...they deteriorate inside and swell up, causing the caliper to hold pressure and not able to return after pedal application..very common w/aged hoses.. pedal pressure is high enough to over-come the restriction and apply force to caliper , but return/release pressure is residual, so the hose acts as a one-way valve due to the interior swell/restriction....

Here is a simple diagnostics trick to iso the problem:

Jack the suspect wheel off ground and apply the brake pedal as hard as you can...now get out and try to hand turn the wheel... if NO , open that bleeder..if the wheel then turns freely, you have a swollen hose...if it does not, you have a frozen caliper [ or e -brake bind]

Simple.............opening the bleeder will release any line pressure to the caliper, so you then know the hose is shot...but if you release pressure w/open bleeder and the caliper is stll holding that wheel, it is not line pressure that is the cause b/c there is no line pressure w/bleeder open.............
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Last edited by Arthur Dalton; 01-03-2009 at 06:44 PM.
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  #5  
Old 01-02-2009, 11:39 PM
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Thanks for the replies... I will check that, OR have my mechanic check it. Is it dangerous to drive this way? I may have to drive the car for about 120 miles for a couple of days (in town driving on Sunday and Tuesday), unless I drive my Lexus, but I may have to lend that to my mother, as her car is in the shop being serviced.

BTW, that wheel is already discolored, so this has either been ongoing, or its happened before. I do not think its been going on for long though, because this is the first time I have noticed it.

I cannot feel it dragging. It will roll on even the slightest grade on my driveway, because at first I was thinking sticking brakes, so I give it a quick check that way.

Thanks again.
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  #6  
Old 01-03-2009, 09:57 AM
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If yu don't know how to open a bleeder , then bring it to someone.................the brakes could lock up.
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Old 01-04-2009, 02:17 AM
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Quote:
Originally Posted by Arthur Dalton View Post
If yu don't know how to open a bleeder , then bring it to someone.................the brakes could lock up.
Thanks. Could I not tell by looking at it? I looked under there this evening (with the headlights from my other car shining under) and the hose does not look swollen. Actually, the hose looks to have been replaced not too long ago.

I could get my dad to help me open the bleeder. Its just finding the time to do it. Hopefully it will be OK Sunday and Tuesday, which are the only two days I will need to drive it (and only about 30 miles each day) of in town driving.
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Old 01-04-2009, 10:40 AM
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Have someone look for you ..checking a brake hose with the headlamps from another car is not the latest and best way to check for a swollen hose... specially when they swell INSIDE...you need to open the bleeder like I took the time to tell you, unless you have X-ray Vision.......
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Last edited by Arthur Dalton; 01-04-2009 at 01:43 PM.
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  #9  
Old 01-04-2009, 01:41 PM
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I don't think you should drive it that way. If the wheel is discolored then it has been getting very hot. If it got worse then it could catch on fire as has been described here before. I don't know the odds but 30 miles is pretty far to drive with the brake on.
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  #10  
Old 01-05-2009, 12:14 AM
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Quote:
Originally Posted by Arthur Dalton View Post
Have someone look for you ..checking a brake hose with the headlamps from another car is not the latest and best way to check for a swollen hose... specially when they swell INSIDE...you need to open the bleeder like I took the time to tell you, unless you have X-ray Vision.......
Unfortunately, I do not have x-ray vision. I will have someone check the hose. It looks fairly new, so obviously if thats the case, the hose is prematurely defective. Is this just a thing with Mercedes cars? I am wondering because I have owned alot of different cars over the years and have never had or heard of one with a swollen brake hose.
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  #11  
Old 01-05-2009, 12:18 AM
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Well, its not discolored bad and it may just be from age since these wheels will be 21 years old next month.

I drove the car 56 miles today with no issues. At each stop, I checked the wheel area and the smell was just faint and the wheel itself was not hot.

I do not think its getting that hot, because at the end of my trips out, I can literally touch the wheel and its not hot at all - just warm. It just has a faint smell of hot brakes at that wheel.

Here is a photo of that wheel from a couple of months ago when someone was wanting to see a photo of my wheels...


Here is one of the front wheel that does not get hot at all - just warm as usual for front brakes. Its kinda faded, but I think its just from age.



Quote:
Originally Posted by mpolli View Post
I don't think you should drive it that way. If the wheel is discolored then it has been getting very hot. If it got worse then it could catch on fire as has been described here before. I don't know the odds but 30 miles is pretty far to drive with the brake on.
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Old 01-05-2009, 12:46 AM
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<have never had or heard of one with a swollen brake hose.
>

Brake hose constriction is one of the most common causes of brake dragging
on any car w/hoses a few years old.
And showing us pictures of your wheels mean nothing...we want to see the rotors.
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Old 01-05-2009, 01:04 AM
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Quote:
Originally Posted by Arthur Dalton View Post
<have never had or heard of one with a swollen brake hose.
>

Brake hose constriction is one of the most common causes of brake dragging
on any car w/hoses a few years old.
And showing us pictures of your wheels mean nothing...we want to see the rotors.
Well, I will take the wheel off and check that hose and take a photo of the rotor. I just posted that photo for polli to show what discoloration I was talking about. I do not think thats from hot brakes. I could be wrong.

I guess I have been lucky with brakes. I have had alot of old cars and currently two 70s cars with perfect brakes, but I did have a 1969 Chevrolet that had a sticking left front brake. Turned out the caliper was bad, but I went ahead and replaced all of the hoses at every wheel.

I will probably just get one of the mechanics to check it this week. I need to get an alignment and new front tires anyway. This would be a good time for all of that I guess.

Thanks.
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  #14  
Old 01-05-2009, 01:06 AM
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This is the thread I was referring to:

Brakes caught fire 1999 C280

Look at post 15
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  #15  
Old 01-05-2009, 01:11 AM
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Yeah...
Iti s a good idea on any older car to jack each wheel and give them a spin after appliyng the pedal, b/c a dragging brake can go on for many miles without being enough to notice , but the parts will wear pre-maturely and you will also effect gas milage.
So , the test is simple , even for one who is not familiar w/brakes.

A good tool for this is those IR temp guns...you just point it to each wheel or rotor and you will see a dragging brake by comparison, after a short drive...they are cheap now.
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Old 01-05-2009, 01:11 AM
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