Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 06-21-2002, 02:16 PM
Snow bum
 
Join Date: Jan 2001
Location: Here and there . . .
Posts: 238
Brake squeal (when brakes are not applied)

One or both of the front wheels on my 1991 300D is/are making a squeaking sound that stops when the brakes are applied. I thought the problem may simply be brake dust, so I gave the discs a thorough spray with the hose. The problem did not stop. The wheels do not always squeak. I would say it happens about 75% of the time. The squeak always stops when I apply the brakes. Any suggestions?

__________________
Ben

The MBs:
1976 300D (W115) - 330K and still going (sort of)
1991 300D 2.5 Turbo - Sold at 221K
1983 280SEL - Sold at 206K
1981 300SD - Sold at 232K
Reply With Quote
  #2  
Old 06-21-2002, 10:42 PM
Ashman's Avatar
Registered User
 
Join Date: Sep 2000
Location: Sherman Oaks, CA
Posts: 4,749
My car did the same thing a while back. the disc itself was loose. I tightened it down and it stopped squeaking.

Alon
__________________
'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon
Reply With Quote
  #3  
Old 06-22-2002, 12:32 AM
ymsin's Avatar
Driver, Mercedes-Benz
 
Join Date: Feb 2001
Location: Malaysia
Posts: 1,645
Check your front brake pads. It could be the time for replacement.
__________________
... Kerry

126 tailed by a 203, 129 leading the pack.
Reply With Quote
  #4  
Old 06-22-2002, 12:35 AM
Registered User
 
Join Date: Apr 2002
Posts: 3,473
Alon, I remembered you told me to tighten the disc, but it doesnt really do anythign considering that you tighten your lug bolts down to 80 ft. lbs or more. Mercedes recomends 80, but I always do 90. It shouldnt do anything by tightening the disc, but I guess it does because it did work a little.

You may want to check the brake pads because they could have gotten cocked inside the brake pad bracket.

I have been fighting the same problem, but when you put on the brakes. Do they squeal when you are about to stop?

My car needs wheel bearings. Im going to do that this weekend, so Ill let you know if it fixes it.

Id try what alon suggests, then if that doesnt work. Let me find out if the wheel bearings fix it.

Since you will have the wheels off anyway, take off the calipers, and put antisieze on the edges of the pad and on the back maybe its binding / stuck on the pistons.


Austin
__________________
Current Stable:
1994 S500 v140, 210k miles, white with grey.

Former Mercedes in the Stable:
1983 300CD Turbo diesel 515k mi sold (rumor has it, that it has 750k miles on it now)
1984 300CD Turbo Diesel 150 k mi sold
1982 300D Turbo Diesel 225 sold
1987 300D Turbo Diesel 255k mi sold
1988 300 CE AMG Hammer 15k mi sold
1986 "300E" Amg Hammer 88k mi sold (it was really a 200, not even an E (124.020)
1992 500E 156k mi sold
etc.
Reply With Quote
  #5  
Old 06-22-2002, 11:26 AM
csnow's Avatar
Registered User
 
Join Date: May 2002
Location: Mass
Posts: 1,127
Often a wheel bearing noise will go away when you brake. Usually, a wheel bearing noise will also go away when you turn in one direction or another at speed.

If only braking stops the noise, I would suspect the pads.
I will presume you already know they are not simply worn out.

This is typically a sign that the pads are not completely releasing for whatever reason.

I know MB prescribes some sort of grease paste for the backs of the pads, but I use the typical parts store 'anti-squeal' paste, which is more like a rubbery adhesive than a grease.
I first discovered that this goo was affective when I had a similar (but worse) problem on my 450SE (12 years ago), and have used it on many various cars with good results ever since. I would rate this one as the remedy "most likely to succeed".

After cleaning up with sandpaper, I apply a very thin coating of heavy Moly grease ('brake grease') to the caliper surfaces that the pads slide on. Of course, the W124 pads do have those nice metal 'shims' to slide on, so they are much less prone to sticking in this way.

Also, while you have it apart, check the caliper pins. If they freeze up, you could get the problem described. If the rubber boots have failed, the pins could be dirty/worn/corroded/stuck. The boots and pins are a cheap replacement part. These actually tend to hold up very well on the W124, but I have seen this problem on other cars. After cleaning, I use a silicone grease on the pins.

Lastly (and worstly), the piston itself could be binding. Folks rarely repair these themselves anymore, since rebuilt calipers are relatively cheap.

Best of luck...
__________________
1986 300E 5-Speed 240k mi.
Reply With Quote
  #6  
Old 06-22-2002, 12:39 PM
amg280's Avatar
Registered User
 
Join Date: Apr 2002
Location: NY
Posts: 530
Lately my 400E has been doing this. Its a squeak coming from the left front wheel. When I turn right, it gets worse, when I turn left, it goes away. When I put the brakes on it goes away. I already cleaned the caliper and pads once, but apparently didnt work. Could it be a bad wheel bearing? I never seen a front one go bad before in these cars. How is the front wheel bearing set up on these? Is it a sealed unit like the back? Or is it like the W126's?

Thanks
__________________
93 300D 2.5 Turbo, Black/Palomino 273K
09 E350 Black/Black 41K
Reply With Quote
  #7  
Old 06-22-2002, 01:42 PM
csnow's Avatar
Registered User
 
Join Date: May 2002
Location: Mass
Posts: 1,127
That is the 'classic' symptom of a bad bearing.
They will typically last "the life of the car" if repacked and resealed every 100k miles or so, but they will eventually wear out otherwise.

Collisions can cause premature failure (potholes, curbs, etc.), though the associated force required would usually bend an alloy wheel in the process, so a surprise failure is unlikely.

Not 100% sure of your model, but my bearings are conventional in every way- 2 tapered bearing sets with a seal at the rear.
__________________
1986 300E 5-Speed 240k mi.
Reply With Quote
  #8  
Old 06-23-2002, 02:50 AM
amg280's Avatar
Registered User
 
Join Date: Apr 2002
Location: NY
Posts: 530
Thumbs up update

Just to update you guys on my problem, I took the pads out, cleaned the calipers, and lubed them up real good. I swapped pads from one side to the other on the caliper. So far the squealin has gone away (fingers crossed). I still dont know why it would go away on a left hand turn, and come back on a right hand one. Hmmm....
__________________
93 300D 2.5 Turbo, Black/Palomino 273K
09 E350 Black/Black 41K
Reply With Quote
  #9  
Old 06-24-2002, 01:06 AM
ymsin's Avatar
Driver, Mercedes-Benz
 
Join Date: Feb 2001
Location: Malaysia
Posts: 1,645
Is the problem solved?
__________________
... Kerry

126 tailed by a 203, 129 leading the pack.
Reply With Quote
  #10  
Old 06-24-2002, 01:01 PM
amg280's Avatar
Registered User
 
Join Date: Apr 2002
Location: NY
Posts: 530
Unhappy No it isnt

Well, Cleaning the pads and calipers only last about a day.

Now what should I do? It definetely made a difference for a little bit? Could it still be a bearing?
__________________
93 300D 2.5 Turbo, Black/Palomino 273K
09 E350 Black/Black 41K
Reply With Quote
  #11  
Old 06-24-2002, 02:48 PM
csnow's Avatar
Registered User
 
Join Date: May 2002
Location: Mass
Posts: 1,127
I still vote for the bearings.
Since it does not appear to be the bearing itself that is making the actual noise, I would speculate that there is some excess play in the hub.
That is why is starts and stops depending upon which way you turn.
Check for play- could be an easy fix.

__________________
1986 300E 5-Speed 240k mi.
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 10:54 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page