I agree with other's that the wheel bearings sound suspect and should be checked. However, in addition to inspecting the wheel bearings (if it were me I'd get new ones regardless how the old ones look and replace the inner seal) check the bearing races. If the races got chewed up sometime in the past, that could be the culprit and the reason why the bearings needed re-tightening. The need to re-tighten should not happen if the cotter pin was installed except for three possible, not mutually exclusive, reasons, in my opinion: 1) The wheel bearings are bad; 2) The bearing races are bad; 3) There is built up gunk behind the wheel bearing seal causing the drum or rotor not to seat completely, explaining the need to re-tighten as the gunk flattened with the stresses of driving. Checking 12/6 and 3/9 might not catch chewed up bearing races. This should show itself by testing in/out play.

Ooops, I just saw that you found and fixed the problem.

Yeah - I did the knuckles as a last resort after changing the wheel bearings and following factory procedures for preload. I think maybe mechs overtightened the bearings in the past and the bearing races may have spun on the knuckle. Bearings are better slightly loose than tight.

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Brian Toscano

I will likely have my mechanic do the front wheel bearings. I've never done it before, and I take this car on long trips all the time. He uses Valvoline high-temp grease (pink). My car is manu. in 10/86 and has pink grease in there already from whoever last serviced the bearings. Is this okay, or is green grease going to save my life?

Brian

You can't go by color. You need to use a grease that's okay for high-temperature wheel bearing application. Typically, that would be a lithium-based, NLGI 2 grade, with EP additives. A good grease is Mobil 1 synthetic. It's red in color.

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95 E320 Cabriolet, 169K

MB sells a tube of fluorescent looking grease that is the correct quantity for wheel bearings. It works great.

Have a great day,

The wheel bearings were replaced. The inner bearings looked almost new, whereas the outside bearings had some brownish coloring on the rollers. Is this normal wear, or indicative that something happened to them in the past? I'm glad I changed the bearings, as they look like they'd been "somewhat" repacked previously - the right side had two different kinds of grease according to the mechanic.


Brian

The brown was from either corrosion or overheat. It is not normal. My guess is that it was from overheating. Overheating first shows up as a "straw" color on the metal surface before going to purple, blue, then black. Corrosion would have shown up with brown grease in the assembly.

The outboard race set sees more "torture" than does the inboard race. This is from cornering forces. So what you saw made sense.

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95 E320 Cabriolet, 169K

The wheel bearings did not fix the problem, for a short time it actually seemed worse! In reviewing the driveline, I've found a klunk when rotating front and rear sections together as a mass. The mechanic says its NOT normal, and coming from inside the tranny. This parallels what the dealer shop foreman told me a little over two months ago, but others were understandably doubtful.

I'm getting the feeling that it comes more and more from the center of the car, but the speeds (70's) are still the same. The steering wheel still vibrate and does the gas pedal. changing tranny gears (even into neutral) will not solve it, and its most noticable when taking foot off gas pedal, e.g. going down hill, less so on partial throttle (level ground).

The other thing that I'm noticing more is that when its hot out, e.g. 95F, my RPM guage is reading upwards of 500 RPM higher under load circumstances, e.g. climbing hill on interstate. When its cooler out, it will be about 2950-3050 at 77 MPH, but when its hot its closer to 3400-3450. Switching A/C on or off while climbing this hill doesn't seem to change this.

Brian

"3. Major problem: On the drive shaft, the rubber center bearing support and center bearing were shot. My support was torn - original part."

Shakes the hell out of er'. The winner for me ( and a rebalance of tires from a true mb tech).

I'll have to insist that normally bearings DO NOT WEAR. Anything less that the original honed finish on the bearing and you have trouble.

Bearings have a unique surface profile that must be maintained to handle the loads. Lubrication is specified such that under normal conditions there is no wear of the metal.

If the bearing surfaces have lost metal, this is catastrophic to the bearing. If the bearing clearances have opened up, then perhaps a mounting surface is worn.

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95 E320 Cabriolet, 169K

One problem turned out to be incorrect front lower control arm installation. I replaced these in August, the vibration went away, enough for me to take a 6300 mile trip from Tennessee to Montana, where I realized how sensitive to wind (another problem).

Local area mechanics could find nothing particularly wrong, except that shocks seemed weak. So, I replaced these. I found I had more vibration in the steering wheel, but less in the footwells. Temperature did not seem to matter anymore. While I was at it, I replaced subframe mounts and springs. Now the car feels more like an MB should.

But I still have that danged vibration, intermittant, in the steering wheel. It still seems to be less likely to vibrate on concrete roads than asphalt. When I shake my wheels at 3 and 9, Both turn together and nothing hops, BUT there is a distinct clunk that seems to come from the steering gear itself and about 1/8" play. The steering is tight, and not too tight, accordingly to local area MB mechanics. But I can't think this "clunk" is a good thing? (All other steering linkage components test Okay and are not more than 13 months old- tie rods, drag link, damper, & idler).

-brian

I replaced the front steering knuckle/hub assembly from another car and so far its taken care of the vibration.

Thanks.

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Brian Toscano

Thanks for posting the update and your solution, it's apreciated by those who do a search about a specific subject/problem. Many who post a question don't bother writing the final solution to their question. Which makes it hard for those who spend hours reading old post, hoping to find a solution to a similar problem.
Thanks

Reviving for new member education.



Have a great day.

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Wow - what an old thread - and now I should update!!

The "final" solution to this problem was replacement of the steering knuckles with FACTORY NEW. I did one knuckle at a time, about 45,000 miles apart (about 9 months for me). When I inspected the first knuckle I changed after 45,000 miles it was still new in appearance with the factory machining. When I set the bearing preload I use the factory procedure...

-brian

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Brian Toscano