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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Peter
1985 300TD 4-speed 212K
1992 400E 343K
2001 E320 72K

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.

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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1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


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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.

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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95 E320 Cabriolet, 169K

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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Peter
1985 300TD 4-speed 212K
1992 400E 343K
2001 E320 72K