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 > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 09-13-2013, 10:44 AM
benhogan's Avatar
CPA/Greasemonkey
 
Join Date: Aug 2009
Location: Chapel Hill
Posts: 1,088
what are the symptoms of bad wheel bearings?

when i drive down the highway at normal highway speed, i get a rythmic groan. i cannot tell if it is speed sensitive but I suspect it is.

i think the only way to test wheel bearings is with a load and maybe a microphone close to the front wheels which is impossible for me.

so is the only way to see is to remove them and visually inspect the rollers?

they are fairly inexpensive parts anyway so I might just change them out. I just need help in the diagnosis.

groan....nothing.....groan...nothing...groan......ugh

__________________
Ben
1987 190d 2.5Turbo
Reply With Quote
  #2  
Old 09-13-2013, 11:04 AM
Diesel911's Avatar
Registered User
 
Join Date: Sep 2007
Location: Long Beach,CA
Posts: 34,955
You did not say which Wheel Bearings. But, I am guessing the front ones.

Safely jack up the front of the Car and rotate the wheels and listen for a grinding sound.

You also might as well Start the Engine and have someone brake hard and release and the rotate the Wheels. If the Wheels do not rotate easily something is preventing your Brake Caliper Pistons from retracting.

Remove the Wheel spread the Brake Pads enough so that they don't Rub; or you could pull the brake pads

If you have a Dial Indicator remove the Hub Cap and set it up to take a reading on the Hub end Play.
You can also pull it back and forth to see if there is any Play.
Rotate the Hub and see if you can feel any roughness or hear a grinding sound.

Of course visual inspection is the ultimate way to check but while simple is some work due to having to clean and re-grease just to see. Changing the Bearings is more work and you face the fact that even the well known name brands of Bearings have 3 or more grades of Bearings. The local Part Store is likely to sell you the made in China grade eve if it is a well known Company.

For Myself If I inspected the Bearings and they were good I would leave them alone and just change the Grease Seal.
Also since I was not successful at adjusting the Hub end play by Hand (I end up over heating the Grease and having to remove the that Grease and do it again) always used the Dial Indicator as the Service Manual tells you and have never had an issue since though I have had the Front Hubs off several times.
__________________
84 300D, 82 Volvo 244Gl Diesel
Reply With Quote
  #3  
Old 09-13-2013, 04:39 PM
Can't Know's Avatar
Registered Slacker
 
Join Date: Sep 2010
Location: Sunny CA
Posts: 733
They can make all kinds of different noises, but considering how inexpensive it is to pull them and clean/inspect/repack(/replace if necessary), I would just do that. The worst part of the whole job is setting the free play, but you can buy the stuff you need at HF for $60 or so (runout indicator and magnetic mount).

I ran that all together, but unless they are actually worn (you can easily tell once you clean them up and start inspecting them) there's no point in replacing them. And if all they need is repacking, you need a pair of wheel seals and some grease, and you're good to go.

Good luck.
Reply With Quote
  #4  
Old 09-14-2013, 12:10 AM
Phil_F_NM's Avatar
Camera Hacker
 
Join Date: Aug 2012
Location: Philadelphia, PA
Posts: 490
Is the groan a single tone or does it increase/decrease proportionally to speed? If not, do a very thorough brake flush and bleed.
I have had this problem on my 300D and I've found that a brake bleed fixes it.
What is happening is the brake pads begin to chatter after the water heats up and expands and that chatter rubs the pad against the rotor until it hits a nice narrowband resonance.

If the tone increases and decreases proportionally to speed, then check your wheel bearings and if it's in the rear, check your CVs.

Phil Forrest
__________________
http://philipforrestphoto.wordpress.com/

1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson
Reply With Quote
  #5  
Old 09-14-2013, 01:07 AM
Mad Scientist
 
Join Date: Dec 2012
Location: Oregon
Posts: 1,535
Does it sound like you have studded snow tires on?
__________________
617 swapped Toyota Pickup, 22-24 MPG, 50k miles on swap
Reply With Quote
  #6  
Old 09-14-2013, 09:32 AM
Registered User
 
Join Date: Jan 2012
Posts: 7,515
NVH Noise Vibration Harshness issues are difficult to find. I doubt it is a front bearing due to the design ( tapered roller ) , when they fail there are more of a old roller skate gravely sound. Rear bearings ( double row angular contact ) make a more of less buzz that will change intensity when you load the car left to right.

What you are describing is something vibrating and going in and out of resonance. If you have a guitar string and subject it to vibration, it will resonate and make a sound when the frequency gets to the resonance point.

Cars make many frequencies at the same time. When the high point of frequencies consider, noise is amplified, when the are opposite , cancel each other out.

The usual suspects are motor / trans mounts that are crushing out, exhaust that has a failed hanger, something out of balance ( fan, drive shaft ) heat shield to tie bar.

My SL has a 36" ish long tie bar running from the front cross member to the body, in the center there is a 1" dia / 1" long rubber mount to hold the bar from vibrating. The mounts are broken and ,under certain conditions, it will resonate for a second or two. I'll get around to fixing it at some point but is isn't critical and I'll end up using industrial parts rather than MB.

Also, the microphone system you are suggesting does exist. It uses piezo electric vibration sensors placed near possible vibration sources. Some of these are wireless, some are hand held for use in diagnosing bearings in an industrial environment.
Reply With Quote
  #7  
Old 09-14-2013, 09:53 AM
Registered User
 
Join Date: Oct 2007
Location: St. Thomas PA
Posts: 957
Remove the suspect front wheel, and retract the pads from the caliper. At this point, it should spin freely, and quietly. If it makes any noise, you need new bearings. To check the rear bearings in this fashion, you should remove the axles from the hub, quite a bit more involved. Replacement is also quite a bit more involved, so hope it's the front bearings making the noise.
__________________
'83 300D, 126K miles.
Reply With Quote
  #8  
Old 09-14-2013, 12:28 PM
toomany MBZ's Avatar
Registered User
 
Join Date: Nov 2006
Location: central Va
Posts: 7,820
Fronts, jack the car up, place hands at 2 o'clock and six o'clock, can you rock the wheel?

Repeat with hands at 3 o'colck and nine o'clock.

If there is play, you need new bearings.

You have two per wheel, an inner and an outer.

As mentioned, use a dial indicator to set the pre load on the outer bearings.

See post #2 here:
Front wheel bearing end play
__________________
83 SD

84 CD
Reply With Quote
  #9  
Old 09-15-2013, 04:04 AM
A work in process...
 
Join Date: Oct 2009
Location: Texas
Posts: 985
I have had tires that were badly worn exhibit this kind of noise. Inspection of the tire/s revealed the extent of the wear.

New tires and a front end inspection/alignment fixed the issue.

Is your front end damper shock in good shape? I doubt if it would cause rhythmic groaning but it might dampen any vibrations.

__________________
Codifex
1981 240D ChinaBlue (Got her running with a donor engine.)
1983 300DTurbo w/sunroof.
1984 300TD manual sunroof. (Electrical Gremlins)

Last edited by Codifex Maximus; 09-15-2013 at 04:08 AM. Reason: Repair grammar/tense.
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 10:28 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page