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  #1  
Old 08-11-2002, 11:20 PM
Benz Crazy
 
Join Date: Aug 2002
Location: NJ
Posts: 67
wheel bearings on '90 420 SEL

1990 MB 420 SEL in generally very good condition. Tires are new.

Problem:

I'm getting a sort of "roar" when I steer to the right at any speed above say 30-35mph. I used the search feature, like a good newbie/lumpy member should, and came up with this thread..

Front End Noise....Bearings?

It seems to support my thinking that my right wheel bearing could be the problem. Anybody concur or disagree?

**Any advice or tips appreciated as I have an apptmnt to have the frt wheel bearings replaced on TUE for a cost of $220.
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1990 420 SEL / 151K mi.
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  #2  
Old 08-12-2002, 10:24 AM
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Join Date: Jun 2002
Location: Motor City, MI
Posts: 2,791
What you described does sound like a bad wheel bearing. Once it's in the shop, the mechanic should immediately see a bad bearing when the wheel is taken apart. The grease seal should be replaced with this job.

If the bearing doesn't show any obvious damage, you'll have to search elsewhere for the cause of the "roar", but I think a new wheel bearing will cure the problem.

Please post back with what the mechanic finds.
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  #3  
Old 08-12-2002, 10:33 AM
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Join Date: Aug 2002
Location: NJ
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Thanks for the reply. My mechanic did indeed say he wanted to inspect it first, to be sure that was the problem.
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  #4  
Old 08-12-2002, 10:04 PM
1992300e
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sounds right

sounds like a wheel bearing, can you feel extra heat on that wheel after you stop driving? Bad bearings generate heat.

PS, I've heard a lot of talk about tightening wheel bearings. Not sure if I would do that, I would think replace would make more sense?

Joel
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  #5  
Old 08-12-2002, 10:20 PM
I told you so!
 
Join Date: Jun 2002
Location: Motor City, MI
Posts: 2,791
Bearings are either perfect or they need to be replaced. They do not wear. I don't know how people here got the impression that bearings need to be tightened. They should be designed in such a way that the clearances (or preload) are reasonably maintained during the life of the bearing. If people are experiencing loose bearings, then they were either improperly installed or something is systematically happening to the mount surfaces causing the races to shift. Bearing problems are not cured by tightening.
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  #6  
Old 08-13-2002, 09:13 AM
1992300e
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tightening Bearings?

I don't know a lot about Mercedes Bearings, but I've been working with bearings in everything from 2 stroke racing bikes through to wheel bearings on other automobiles.

I could not think of a good reason why you would need to tighten a bearing to fix it. Other than the obvious bolt backing off.

For the cost, importance, and huge wear that bearing get I would think no brainer to replace?

Not sure why people say to tighten them, I actually heard a mechanic say this "tightening bearings" just the other day in his shop to a client.

Seems more like a quick, gonna sell this car to someone else, fix.

Joel
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  #7  
Old 08-13-2002, 10:57 AM
I told you so!
 
Join Date: Jun 2002
Location: Motor City, MI
Posts: 2,791
Unless the bearing shows unacceptable indications or the vehicle has ultrahigh miles, I would simply clean, regrease, and install bearing with new seals.

Unacceptable indications would include:

1. Presence of spalls on bearing working surfaces
2. Cracks in any of the bearing components
3. Particle denting of the raceway
4. Frosty (or matte) appearance on raceway
5. Discoloration from overheating
6. Corrosion of the bearing
7. Highly polished bearing surface (mirror-finish)
8. Darkening or fluting of the bearing surface
9. ANY evidence of loss of metal on the bearing surfaces

Stay away from that mechanic recommending to tighten the bearings.
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  #8  
Old 08-13-2002, 01:30 PM
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Join Date: Jul 2001
Location: SoCal
Posts: 1,303
Besides a bad bearing, a brake problem could cause the noise. It is usually not difficult to move the caliper out of the way, remove the pads, and spin the hub to find a bearing problem yourself. Any hint of roughness, binding, or noise is bad. Tapered bearings should not be preloaded, and a small amount of play is normal. This means the hub should spin freely, with no vibration, grinding or roughness felt with your fingers touching the axle stub (any cap on hub removed).

Steve
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  #9  
Old 08-13-2002, 06:06 PM
Benz Crazy
 
Join Date: Aug 2002
Location: NJ
Posts: 67
Just picked it up from the shop ( MB Auto Tech in Berlin, NJ < tell them Todd sent ya > ) and it was indeed a bad frt wheel bearing. I had both left and right done, since I had it in there and I'm up over 114K mi.

The bad bearing showed symptom #'s 2,5,6,7 and 9 in Kesta's list so it was a no brainer to replace it. He did the whole nine with respect to replacing the bearings, grease seals, caps etc.

Steering noise ("roar") is gone and frt end feels nice and tight. I celebrated by running it up to a 100 MPH on the Atlantic City Expressway on the ride home.

I want to thank you all for your input and knowledge. It's much appreciated by someone like me who is not especially mechanically inclined. There's nothing worse than throwing money at something and not solving the problem at hand.

Quick pic of the Land Shark !

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1990 420 SEL / 151K mi.

Last edited by Todd W126; 08-13-2002 at 09:54 PM.
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