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  #1  
Old 04-04-2006, 08:53 AM
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bearing failure 400E

My wife's 400E recently experienced right front wheel bearing failure. SHe started feeling some wobble while driving on the highway, pulled over, and smoke was coming from the wheel, which was also covered in grease.

When she got it to my tech, he said the heat had actually fused the bearing to the spindle. Being the good friend that he is, he proceeded to read me the riot act about how I could ignore the noise the bearing was making before it failed. Truth is, my wife has a great ear for car sounds, and good sense for when things ain't right, and neither she or I heard or felt any giveaway signs. I replaced those bearings less than two years ago, and on a recent maintenance I retightened the bearings on both sides.

My question is what might have caused the failure and why would we not have had any warning? I have two theories.

One is that I overtightened the bearing. The second is that I may have mixed different types of grease, which I have heard will sometimes interact with the result of thinning and decreased effectiveness.

Neither of those theories feel right to me. Any ideas? The wife REALLY does not like breaking down on the highway.

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1985 300TD 4-speed 212K
1992 400E 343K
2001 E320 72K
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  #2  
Old 04-04-2006, 09:45 AM
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ich fahre, also bin ich
 
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Re: Bearing failure

I have experienced only two bearing falures: 1 on a Ford WIndstar that howled on every turn to foretell its imminent demise, and one on a trailer wheel that fused itself to the spindle like yours.

My guess is that the berings weren't 100% seated correctly?? Just a theory, since 2 years is an awfully short lifespan. I agree that grease mixing is an unlikely culprit.

If your mech continues to berate you, make him prove his virility by restoring the spindle using only a chisel, file and sandpaper like the old gas station mechanic from Churchville, South Carolina did on the trailer wheel in 1984. And he only charged $48, even after he busted his hand open on the job.
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  #3  
Old 04-04-2006, 10:12 AM
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my wife has become very sensitive with car noises as well.

I think your wife did the absolute best she could do under the circumstances.

You should dump a mechanic with that attitude.

It is somewhat rare to replace a front bearing on a MB anyway.

I wonder why you had to replace yours a couple of years ago?
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1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

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  #4  
Old 04-04-2006, 11:40 AM
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Question Bearing preload?

Peter, You say you retightened both front wheel bearings on this car recently,can you describe how you went about this and what preload ,if any ,you used.
Geo.
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  #5  
Old 04-04-2006, 01:48 PM
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I look at failed bearings daily for a bearing manufacturer. Usually bearing fail with the onset of spalling (for any of a number of reasons), then progress slowly until it gets louder and eventually reaches complete failure. I can't conceive of (nor have I seen) a failure where a bearing goes from good to seizure on the freeway in under a minute without prior warning.

You hint that you are unsure of the bearing preload and regreasing procedure you used at the last service. WHy were the bearings retightened? Normally they shouldn't be touched unless they are either regreased, replaced, or opened for inspection. I'd like to point out that most bearing failures result from improper installation, and not from some intrinsic defect in the part.
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  #6  
Old 04-04-2006, 02:58 PM
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Easy on my tech, guys, I was speaking tongue in cheek, he is a great guy. Just decided to rib me about how I let this happen. ANd my wife is very perceptive, can usually smell and hear things long before I do, so she is usually the lead on troubleshooting. Including how long since my last shower!

My tech's father (also a MB tech) taught me a tightening process by feel, so I can't answer the pre-load question, which was why I suspected that first. Tighten and loosen in a rocking motion until you are getting no more progress, tighten till you can feel resistance rolling the wheel, then back the nut off a pinch.

I replaced the bearings initially in a noise hunt. We had been hearing a very sporadic noise, like blowing in a bottle, which had me and my tech stumped. Went away during braking, but would come and go at no particular time, speed, or orientation of the front wheels, sometimes for days. What seems to have fixed it finally was filing rust out of the brake pad seats.

I detected some side-to-side play in the wheel last time I had the car in the air, just figured I'd take some of that play out. Probably a bad move in retrospect. I doubt the bearing hadn't seated, that car has been 10K miles at least since the installation, that's too long for the hub to be that loose.

Still can't believe that the failure would be that sudden. Let's say I did overtighten it. Why no warning? And if my wheels are rolling freely in the air, can it have been THAT tight?
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1985 300TD 4-speed 212K
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  #7  
Old 04-04-2006, 04:54 PM
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Peter, sounds from the RF wheel bearing were likely drowned out by the engine and road noise. If the LF wheel bearing had a problem you and your wife would be more apt to hear it.
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  #8  
Old 04-05-2006, 07:33 AM
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I recently had the same thing happen to my 190e2.6, except on the left inner front bearing.

Since I usually drive on the left lane, I believe that the inner left front bearing had been stressed more than that on the right, since the road slopes down slightly to the left in that lane (as it is designed for water drainage purposes). It was also for that reason that I suddenly heard this expensive clicking sound, since the sound bounced off the concrete divider, making me hear it more easily and more consistently, above the engine and road noise at highway speed.

I instinctively slowed down and moved to the middle lane, and the noise was reduced and came on sporadically - this was because the road surface was more or less level in the middle lane. But by then it was too late, and shortly afterwards, I heard a really expensive-sounding noise that meant that the bearing was eating itself up inside.

Bringing it to the shop, they found that the inner bearing had eaten into the spindle and the hub, which cost me $$$ and time to replace, since it was not readily sourced.

What bothered me was that this happened without warning as well. It seems that it should now be part of my routine to check the front bearings whenever I rotate the tires, for example.
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  #9  
Old 04-12-2006, 01:37 PM
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solved

Replaced the entire hub on the passenger side. The next week my wife heard a whining that she is sure preceded the first failure, and sure enough the driver's side was on its way, feeling gravelly to the touch while spinning the hub in the air. Replaced the bearings. My tech agrees and I concede I overtightened both.

He retightened by feel, no special tools.

I was waiting for chastisement about not going by the book! I am properly chastised by the silence!

Thanks for the feedback.
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1985 300TD 4-speed 212K
1992 400E 343K
2001 E320 72K
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  #10  
Old 04-12-2006, 07:19 PM
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wheel bearing failure

If you used your fingers to tighten the adjusting nut--it is HIGHLY unlikely you over tightened, unless the bearing/hub were real cold at the time. Heat up could result in overload and rapid failure by spalling,etc.

Mixing greases can be deadly to bearings. NEVER mix types or brands unless you are certain they are fully compatible. Greases made from different 'soaps' are not compatible.

Once I consullted with nuclear power plant operator on this--they had used a different than OEM grease in all the valve actuators (more than 2000!) without completely stripping and cleaning out the old. I HAD to advise them to completely disassemble and clean them, replacing all the seals. The greases were different soaps, and synthetic oil vs mineral oil--totally incompatible. Cost them several million$. Only parts more costly than medical are nuclear!

In all my years of driving the world over, from pedal powered bicycles to very fast jet aircraft, never had a wheel bearing fail suddenly like reported. Have had dirt ingress chew them up on plows. Have had 'sealed ' rear axle bearings on '59 Ford Fairline fail from impact caused spalling due to very rough country roads. I wonder what caused your failure?

Modern wheel bearings just do not fail.
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  #11  
Old 04-12-2006, 09:26 PM
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ich fahre, also bin ich
 
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Wheel bearing failure

While some greases may be incompatible, 10:1 or higher that it wasn't your problem (assuming they were both high temp wheel greases). See:

http://www.mindconnection.com/library/handyman/greasecompat.htm

and

http://www.noria.com/message_boards/message_details_by_list.asp?foldername=mixing+incompatible+greases&messagenumber=4787

As to the nuke plant operator, we know they had to fail on the safe side regardless of the real risks, once the consultant hath spoken. Why didn't you just recommend cleaning or flushing of the grease?:wtf: Now the consumer has to fork out the millions in higher electric costs.
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  #12  
Old 04-13-2006, 09:05 AM
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Kebowers, tightened by hand, with tool, not fingers. You do have to load the hub assembly with some force, then back off, can't do that without more leverage than fingers. And in that scenario, cockiness or boneheadedness must have gotten me in trouble.

Everyone says the bearings rarely fail, and that is probably true. It is the sometimes that matter, eh?

As to the grease, I have heard both ends from experts: some greases are compatible with all, never mix different greases. I'll stick to the safe way: clean everything up, rinse the hub of residual grease, and pack bearings and hub with fresh grease. Can't hurt, takes no real time or effort once you are that deep into a job.

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1985 300TD 4-speed 212K
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