300D Bearing help

[JHZR2]

Hi,

Thanks to psfred in my other post,I now know where to find the grease seals for the front bearings. My question is now, I had them replaced about 10K miles ago. on the front wheels, at the center cap, it is often rather dirty/greasy, and I suppose this is due to the grease escaping from the bearings. Because of this, I have to wonder if perhaps I should replace them, since they are so cheap. However since they were done so recently, and the grease escaping cant be too great, perhaps they are still ok.

How long do wheel bearings typically last, and how often should one repack them?

Can I use Mobil1 grease? It will not be displaced by water, and has a very high melting point. Or, are bearing greases designated especially as such?

What about the rear bearings? Ive never done anything about them, but read that tehy arent exactly a DIY job. Thats fine, but since Ill be replacing my rotors, Ill assume I shall come into contact with them in one form or another. Under the same heading as the grease seals for the front bearings, there are also ones specified for rear outer and inner. Will I be messing with these when doing rear rotors? Should I replace them? Can I replace them?

Thanks

JMH

[MarkM]

Grease may be escaping from front bearing cap because of poorly fitting cap or too much grease, or simple since you just did the work a short time ago and things are "settling down". the same thing happened on my car...eventually it stopped, and there is still plenty of grease in there. I think I would probably replace the caps since they are so cheap.

Front bearings usually last 100,000 miles or more....you replace them when they fail..you will hear squealing, moaning or grinding when they fail (depending on actual failure mode). You might get more mileage out of them if you clean and repack them every time you replace brake rotors. It is important that the castellated nut is adjusted properly when replacing the hub...it should be neither too loose nor too tight...the wheel should rotate freely with little restriction, but there should also be no play.

Mobile 1 synthetic grease is great for front bearings.

Rear bearings are a whole different story......you dont touch them when you do rear rotors....the rear bearings are in the hub not in the rotor assembly as on the front....remember...in the rear there are no spindles.

You may never have to do anything with rear bearings during the life of the car...they are not routinely replaced. On these vehicles which may last up to 500,000 miles or more, you may at some point have to replace them, but it is still very uncommon to do so.

The front bearings undergo a lot more stress and wear due to steering which causes multiple forces in different directions, and they absorb most of the stopping forces when braking. The rear bearings are much simpler with wheels fixed on only one axis, and rear wheels play a minor role in stopping the car during braking. The rear wheel bearings are maintenance-free.

[psfred]

As I learned on another thread, the Mobil 1 grease (or any other very high melting point grease) won't ooze out and make a mess.

If you do get new dust covers, be careful putting them on. They can fit SO tight the seal completely and pop off -- most american ones have a hole in them to prevent this, MB doesn't. Big pain, no easy cure except to put the old worn one back in.

Do not, however, drive them on with a mallet or hammer by hitting them on the top, they will bend and close the mouth up or go out of round, then leak or pop off. Use a chisel, punch, or drift and tap around the lip at the bottom, that is what it is there for.

Peter

[ATLD]

Used Mobile 1 syn grease on all bearings and CV joints on my BMW recently. Noticed some oozing, but discovered that the grease was reacting with some anti-sieze compound left on my hub where the cap contacts. Otherwise, the car never rolled so easy! Personally, I thik it't the best grease. Just make sure that you really clean everything well first, so you don't mix greases. That can cause the grease to liquify into oil byproducts and that's bad news for bearings. Did you use the proper grease for the bearings? I don't think that Mobile claims universal compatibility, like castrol does, but I still go with mobile.

ATLD